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  • 51.
    Friberg, Anders
    et al.
    KTH, Superseded Departments (pre-2005), Speech, Music and Hearing.
    Sundberg, Johan
    KTH, Superseded Departments (pre-2005), Speech, Music and Hearing.
    Time discrimination in a monotonic, isochronous sequence1995In: Journal of the Acoustical Society of America, ISSN 0001-4966, E-ISSN 1520-8524, The Journal of the Acoustical Society of America, Vol. 5, no 98, p. 2524-2531Article in journal (Refereed)
    Abstract [en]

    In acoustic communication timing seems to be an exceedingly important aspect. The just noticeable difference ~jnd! for small perturbations of an isochronous sequence of sounds is particularly important in music, in which such sequences frequently occur. This article reviews the literature in the area and presents an experiment designed to resolve some conflicting results in the literature regarding the tempo dependence for quick tempi and relevance of music experience. The jnd for a perturbation of the timing of a tone appearing in an isochronous sequence was examined by the method of adjustment. Thirty listeners of varied musical background were asked to adjust the position of the fourth tone in a sequence of six, such that they heard the sequence as perfectly isochronous. The tones were presented at a constant interonset time that was varied between 100 and 1000 ms. The absolute jnd was found to be approximately constant at 6 ms for tone interonset intervals shorter than about 240 ms and the relative jnd constant at 2.5% of the tone interonsets above 240 ms. Subjects’ musical training did not affect these values. Comparison with previous work showed that a constant absolute jnd below 250 ms and constant relative jnd above 250 ms tend to appear regardless of the perturbation type, at least if the sequence is relatively short.

  • 52.
    Gaborit, Mathieu
    et al.
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Marcus Wallenberg Laboratory MWL. Le Mans Univ, Lab Acoust, CNRS, UMR 6613,Univ Mans, F-72000 Le Mans, France.
    Dazel, Olivier
    Le Mans Univ, Lab Acoust, CNRS, UMR 6613,Univ Mans, F-72000 Le Mans, France..
    Göransson, Peter
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Marcus Wallenberg Laboratory MWL.
    A simplified model for thin acoustic screens2018In: Journal of the Acoustical Society of America, ISSN 0001-4966, E-ISSN 1520-8524, Vol. 144, no 1, p. EL76-EL81Article in journal (Refereed)
    Abstract [en]

    A generalization of the commonly used pressure jump modeling of thin porous layers is proposed. The starting point is a transfer matrix model of the layer derived using matrix exponentials. First order expansions of the propagating terms lead to a linear approximation of the associated phenomena and the resulting matrix is further simplified based on physical assumptions. As a consequence, the equivalent fluid parameters used in the model may be reduced to simpler expressions and the transfer matrix rendered sparser. The proposed model is validated for different backing conditions, from normal to grazing incidence and for a wide range of thin films. In the paper, the physical hypotheses are discussed, together with the origin of the field jumps.

  • 53. Galembo, A.
    et al.
    Askenfelt, Anders
    KTH, Superseded Departments, Speech Transmission and Music Acoustics.
    Cuddy, L. L.
    Russo, F. A.
    Effects of relative phases on pitch and timbre in the piano bass range2001In: Journal of the Acoustical Society of America, ISSN 0001-4966, E-ISSN 1520-8524, Vol. 110, no 3, p. 1649-1666Article in journal (Refereed)
    Abstract [en]

    Piano bass tones raise questions related to the perception of multicomponent, inharmonic tones. In this study, the influence of the relative phases among partials on pitch and timbre was investigated for synthesized bass tones with piano-like inharmonicity. Three sets of bass tones (A0 = 27.5 Hz, 100 partials, flat spectral envelope) were generated; harmonic, low inharmonic, and high inharmonic. For each set, five starting phase relations among partials were applied; sine phases, alternate (sine/cosine) phases, random phases, Schroeder phases, and negative Schroeder phases. The pitch and timbre of the tones were influenced markedly by the starting phases. Listening tests showed that listeners are able to discriminate between tones having different starting phase relations, and also that the pitch could be changed by manipulating the relative phases (octave, fifth, major third). A piano-like inharmonicity gives a characteristic randomizing effect of the phase relations over time in tones starting with nonrandom phase relations. A measure of the regularity of the phase differences between adjacent partials is suggested for quantifying this randomization process. The observed phase effects might be of importance in synthesizing, recording, and reproducing piano music.

  • 54. Goebl, W.
    et al.
    Bresin, Roberto
    KTH, Superseded Departments, Speech Transmission and Music Acoustics.
    Measurement and reproduction accuracy of computer-controlled grand pianos2003In: Journal of the Acoustical Society of America, ISSN 0001-4966, E-ISSN 1520-8524, Vol. 114, no 4, p. 2273-2283Article in journal (Refereed)
    Abstract [en]

    The recording and reproducing capabilities of a Yamaha Disklavier grand piano and a Bosendorfer SE290 computer-controlled grand piano were tested, with the goal of examining their reliability for performance research. An experimental setup consisting of accelerometers and a calibrated microphone was used to capture key and hammer movements, as well as the acoustic signal. Five selected keys were played by pianists with two types of touch (staccato and legato). Timing and dynamic differences between the original performance, the corresponding MIDI file recorded by the computer-controlled pianos, and its reproduction were analyzed. The two devices performed quite differently with respect to timing and dynamic accuracy. The Disklavier's onset capturing was slightly more precise (+/-10 ms) than its reproduction (-20 to +30 ms); the Bosendorfer performed generally better, but its timing accuracy was slightly less precise for recording (-10 to 3 ms) than for reproduction (+/-2 ms). Both devices exhibited a systematic (linear) error in recording over time. In the dynamic dimension, the Bosendorfer showed higher consistency over the whole dynamic range, while the Disklavier performed well only in a wide middle range. Neither device was able to capture or reproduce different types of touch.

  • 55. Goebl, W.
    et al.
    Bresin, Roberto
    KTH, School of Computer Science and Communication (CSC), Speech, Music and Hearing, TMH, Music Acoustics.
    Galembo, A.
    Touch and temporal behavior of grand piano actions2005In: Journal of the Acoustical Society of America, ISSN 0001-4966, E-ISSN 1520-8524, Vol. 118, no 2, p. 1154-1165Article in journal (Refereed)
    Abstract [en]

    This study investigated the temporal behavior of grand piano actions from different manufacturers under different touch conditions and dynamic levels. An experimental setup consisting of accelerometers and a calibrated microphone was used to capture key and hammer movements, as well as the sound signal. Five selected keys were played by pianists with two types of touch (pressed touch versus struck touch) over the entire dynamic range. Discrete measurements were extracted from the accelerometer data for each of the over 2300 recorded tones (e.g., finger-key, hammer-string, and key bottom contact times, maximum hammer velocity). Travel times of the hammer (from finger-key to hammer-string) as a function of maximum hammer velocity varied clearly between the two types of touch, but only slightly between pianos. A travel time approximation used in earlier work [Goebl W., (2001). J. Acoust. Soc. Am. 110, 563-572] derived from a computer-controlled piano was verified. Constant temporal behavior over type of touch and low compression properties of the parts of the action (reflected in key bottom contact times) were hypothesized to be indicators for instrumental quality.

  • 56. Goebl, Werner
    et al.
    Bresin, Roberto
    KTH, School of Computer Science and Communication (CSC), Speech, Music and Hearing, TMH, Music Acoustics. KTH, School of Computer Science and Communication (CSC), Media Technology and Interaction Design, MID.
    Fujinaga, Ichiro
    Perception of touch quality in piano tones2014In: Journal of the Acoustical Society of America, ISSN 0001-4966, E-ISSN 1520-8524, Vol. 136, no 5, p. 2839-2850Article in journal (Refereed)
    Abstract [en]

    Both timbre and dynamics of isolated piano tones are determined exclusively by the speed with which the hammer hits the strings. This physical view has been challenged by pianists who emphasize the importance of the way the keyboard is touched. This article presents empirical evidence from two perception experiments showing that touch-dependent sound components make sounds with identical hammer velocities but produced with different touch forms clearly distinguishable. The first experiment focused on finger-key sounds: musicians could identify pressed and struck touches. When the finger-key sounds were removed from the sounds, the effect vanished, suggest- ing that these sounds were the primary identification cue. The second experiment looked at key- keyframe sounds that occur when the key reaches key-bottom. Key-bottom impact was identified from key motion measured by a computer-controlled piano. Musicians were able to discriminate between piano tones that contain a key-bottom sound from those that do not. However, this effect might be attributable to sounds associated with the mechanical components of the piano action. In addition to the demonstrated acoustical effects of different touch forms, visual and tactile modalities may play important roles during piano performance that influence the production and perception of musical expression on the piano.

  • 57.
    Granqvist, Svante
    et al.
    KTH, Superseded Departments, Speech, Music and Hearing.
    Hammarberg, Britta
    The correlogram: A visual display of periodicity2003In: Journal of the Acoustical Society of America, ISSN 0001-4966, E-ISSN 1520-8524, Vol. 114, no 5, p. 2934-2945Article in journal (Refereed)
    Abstract [en]

    Fundamental frequency (F-0) extraction is often used in voice quality analysis'. In pathological voices with a high degree of instability in F-0, it is common for F-0 extraction algorithms to fail. In such cases, the faulty F-0 values might spoil the possibilities for further data analysis. This paper presents the correlogram, a new method of displaying periodicity. The correlogram is based on the waveform-matching techniques often used in F-0 extraction programs, but with no mechanism to select an actual F-0 value. Instead, several candidates for F-0 are shown as dark bands. The result is presented as a 3D plot with time on the x axis, correlation delay inverted to frequency on the y axis, and correlation on the z axis. The z axis is represented in a gray scale as in a spectrogram. Delays corresponding to integer multiples, of the period time will receive high correlation, thus resulting in candidates at F-0, F-0/2, F-0/3, etc. While the correlogram, adds little to F-0 analysis of normal voices, it is useful for analysis of pathological voices since it illustrates the full. complexity of the periodicity in the voice signal. Also, in combination with manual tracing, the correlogram can be used for semimanual F-0 extraction. If so, F-0 extraction can be performed on many voices that cause problems for conventional F-0 extractors. To demonstrate the properties of the method it is applied to synthetic and natural voices, among them six pathological voices, which are characterized by roughness, vocal fry, gratings/scrape, hypofunctional breathiness and voice breaks, or combinations of these.

  • 58.
    Granqvist, Svante
    et al.
    KTH, Superseded Departments, Speech, Music and Hearing.
    Lindestad, Per-Åke
    A method of applying Fourier analysis to high-speed laryngoscopy2001In: Journal of the Acoustical Society of America, ISSN 0001-4966, E-ISSN 1520-8524, Vol. 110, no 6, p. 3193-3197Article in journal (Refereed)
    Abstract [en]

    A new method for analysis of digital high-speed recordings of vocal-fold vibrations is presented. The method is based on the extraction of light-intensity time sequences from consecutive images, which in turn are Fourier transformed. The spectra thus acquired can be displayed in four different modes, each having its own benefits. When applied to the larynx, the method visualizes oscillations in the entire laryngeal area, not merely the glottal region. The method was applied to two laryngoscopic high-speed image sequences. Among these examples, covibrations in the ventricular folds and in the mucosa covering the arytenoid cartilages were found. In some cases the covibrations occurred at other frequencies than those of the glottis.

  • 59.
    Granqvist, Svante
    et al.
    KTH, School of Computer Science and Communication (CSC), Speech, Music and Hearing, TMH, Speech Communication and Technology.
    Sundberg, Johan
    KTH, School of Computer Science and Communication (CSC), Speech, Music and Hearing, TMH.
    Lundberg, J. O.
    Weitzberg, E.
    Paranasal sinus ventilation by humming2006In: Journal of the Acoustical Society of America, ISSN 0001-4966, E-ISSN 1520-8524, Vol. 119, no 5, p. 2611-2617Article in journal (Refereed)
    Abstract [en]

    The gas nitric oxide (NO) is generated in the human paranasal sinuses and can be measured in nasally exhaled air. During humming, a marked increase in exhaled NO content has been observed. The acoustic phenomenon responsible for this evacuation of NO gas from the sinuses was analyzed. A tube model was constructed with a syringe containing NO gas attached radially. This tube was excited with an air stream modulated by a sine wave. Increased evacuation was observed whenever the syringe was not located at a pressure node of the exciting sine wave. A computer model of the system showed a good matching of observed pressure versus frequency data in the syringe resonator. The results thus suggest that the alternating pressure in the nasal cavity forces the air plug in the ostium of the paranasal sinus resonators to vibrate, thus expelling from the cavity NO gas, which is transported to free air by the exhalatory air stream.

  • 60.
    Grell, Anke
    et al.
    KTH, School of Computer Science and Communication (CSC), Speech, Music and Hearing, TMH.
    Sundberg, Johan
    KTH, School of Computer Science and Communication (CSC), Speech, Music and Hearing, TMH.
    Ternström, Sten
    KTH, School of Computer Science and Communication (CSC), Speech, Music and Hearing, TMH, Music Acoustics.
    Ptok, Martin
    Altenmueller, Eckart
    Rapid pitch correction in choir singers2009In: Journal of the Acoustical Society of America, ISSN 0001-4966, E-ISSN 1520-8524, Vol. 126, no 1, p. 407-413Article in journal (Refereed)
    Abstract [en]

    Highly and moderately skilled choral singers listened to a perfect fifth reference, with the instruction to complement the fifth such that a major triad resulted. The fifth was suddenly and unexpectedly shifted in pitch, and the singers' task was to shift the fundamental frequency of the sung tone accordingly. The F0 curves during the transitions often showed two phases, an initial quick and large change followed by a slower and smaller change, apparently intended to fine-tune voice F0 to complement the fifth. Anesthetizing the vocal folds of moderately skilled singers tended to delay the reaction. The means of the response times varied in the range 197- 259 ms depending on direction and size of the pitch shifts, as well as on skill and anesthetization.

  • 61.
    Gudmarsson, Anders
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Highway and Railway Engineering.
    Ryden, N.
    Birgisson, Björn
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Highway and Railway Engineering.
    Application of Resonant Acoustic Spectoscopy to Beam Shaped Asphalt Concrete Samples2010In: Journal of the Acoustical Society of America, ISSN 0001-4966, E-ISSN 1520-8524, Vol. 128, no 4, p. 2453-2453Article in journal (Refereed)
    Abstract [en]

    The dynamic modulus of asphalt concrete is a key parameter needed in modern pavement design and management. Traditional laboratory tests based on cyclic loading (0.1–25 Hz) at different testing temperatures are time consuming and require expensive equipment. There is therefore a need for more efficient non‐destructive methods to determine the dynamic modulus of asphalt concrete. This study applies resonant acoustic spectroscopy (RAS) to beam shaped asphalt concrete samples. Multiple modes of vibration are measured at each testing temperature using a miniature accelerometer and a small steel sphere as impact source. The complex modulus from each resonant frequency is calculated using the Rayleigh–Ritz method. The heterogeneous and viscoelastic nature of asphalt concrete presents challenges to the application of conventional RAS. The number of measurable modes decreases with increasing test temperature. In an attempt to extend the usable frequency and temperature range measured, transfer functions are inverted using the finite element method along with a frequency dependent complex modulus. Initial results indicate that RAS can be an efficient method for the prediction of the high‐frequency part of the asphalt concrete dynamic modulus mastercurve.

  • 62.
    Gudmarsson, Anders
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Highway and Railway Engineering.
    Rydén, Nils
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Highway and Railway Engineering.
    Birgisson, Björn
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Highway and Railway Engineering.
    Characterizing the low strain complex modulus of asphalt concrete specimens through optimization of frequency response functions2012In: Journal of the Acoustical Society of America, ISSN 0001-4966, E-ISSN 1520-8524, Vol. 132, no 4, p. 2304-2312Article in journal (Refereed)
    Abstract [en]

    Measured and finite element simulated frequency response functions are used to characterize the low strain (similar to 10(-7)) complex moduli of an asphalt concrete specimen. The frequency response functions of the specimen are measured at different temperatures by using an instrumented hammer to apply a load and an accelerometer to measure the dynamic response. Theoretical frequency response functions are determined by modeling the specimen as a three-dimensional (3D) linear isotropic viscoelastic material in a finite element program. The complex moduli are characterized by optimizing the theoretical frequency response functions against the measured ones. The method is shown to provide a good fit between the frequency response functions, giving an estimation of the complex modulus between minimum 500 Hz and maximum 18 vertical bar 000 Hz depending on the temperature. Furthermore, the optimization method is shown to give a good estimation of the complex modulus master curve.

  • 63. Guettler, K.
    et al.
    Askenfelt, Anders
    KTH, School of Computer Science and Communication (CSC), Speech, Music and Hearing, TMH, Music Acoustics.
    Buen, A.
    Double basses on the stage floor: Tuning fork–table top effect or not?2012In: Journal of the Acoustical Society of America, ISSN 0001-4966, E-ISSN 1520-8524, Vol. 131, no 1, p. 795-806Article in journal (Refereed)
    Abstract [en]

    The question whether or not double basses can benefit from a compliant and radiating stage floor in the low end of their tonal register, similar to the well-known tuning fork–tabletop effect, was examined through field experiments in five concert halls. The topic comprises several aspects: (1) How well the mechanical impedances of double basses and the stage floor match, (2) amount of vibration velocity transmitted to the floor through the end pin of the bass, and (3) radiation efficiency of point-excited bending waves in the stage floor far below the coincidence frequency. Each aspect represents a prerequisite for the tuning fork–tabletop effect to take place. The input impedance at the end pin was measured for three representative double basses. The stage floors of five orchestra halls were measured with respect input impedance and damping, while sound radiation to the audience area was measured for two of them. In Lindeman Hall, Oslo, all conditions for the tuning fork–tabletop effect to take place were clearly met. The contribution from the stage-floor radiation to the sound pressure level in the audience area was found to be about 5 dB between 40 and 60 Hz, and even higher between 30 and 40 Hz.

  • 64. Gustafsson, M.
    et al.
    He, Sailing
    KTH, Superseded Departments, Electromagnetic Theory.
    An optimization approach to multi-dimensional time domain acoustic inverse problems2000In: Journal of the Acoustical Society of America, ISSN 0001-4966, E-ISSN 1520-8524, Vol. 108, no 4, p. 1548-1556Article in journal (Refereed)
  • 65.
    Haikonen, Kalle
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Electricity.
    Underwater radiated noise from direct driven Wave Energy Converters: Sound Pressure Levels in relation to Significant Wave Height and Wave Steepness2014In: Journal of the Acoustical Society of America, ISSN 0001-4966, E-ISSN 1520-8524Article in journal (Refereed)
    Abstract [en]

    The operation of Wave Energy Converters (WECs) will add to the anthropogenic impact on the marine environment. Underwater radiated noise is one suggested impact. To estimate if there might be an impact on the environment, the noise must be characterized. Noise from two full scale WECs was measured in 2013. The purpose of this study was to examine the change in noise levels from the WECs in different significant wave heights and wave Steepness, propagation loss and the significance of a noise dampening feature. Noise was measured simultaneously at two distances (1m and 150 m). Noise levels at 1m varied between 108-143 dB re 1 µParms in Hs 0.09-2.84m. The noise dampening feature had a significant impact on the noise levels. Noise levels increased logarithmically in relation to Hs and linearly in relation to α2. α2 was found to be an uncertain variable when used alone to estimate noise levels.

  • 66. Hedberg, Claes
    Multifrequency plane, nonlinear, and dissipative waves at arbitrary distances1999In: Journal of the Acoustical Society of America, ISSN 0001-4966, E-ISSN 1520-8524, Vol. 106, no 6, p. 3150-3155Article in journal (Refereed)
    Abstract [en]

    A solution for multifrequency plane waves propagating through a dissipative and nonlinear medium is presented. It originates from the well-known Bessel function series ratio for a pure sinusiodal wave, introduced by Cole and Mendousse. The solution is exact. The only limitation, inherited from the single-frequency solution, is the slow convergence of the series when the nonlinearity is very large compared to the dissipation. Otherwise any frequencies, amplitudes and phases can be introduced in the original wave and the solution is valid for any propagated distance.

  • 67. Hedberg, Claes
    et al.
    Rudenko, Oleg
    Pulse response of a nonlinear layer2001In: Journal of the Acoustical Society of America, ISSN 0001-4966, E-ISSN 1520-8524, Vol. 110, no 5, p. 2340-2350Article in journal (Refereed)
    Abstract [en]

    A simple analytical theory is developed for the description of non-steady state response of a thin nonlinear layer, which differs markedly in its linear properties from the surrounding medium. Such a layer can model the behavior of real inhomogeneities like a cloud of gas bubbles in a liquid, a crack or split plane in a solid, or the contact between two slightly tighted rough surfaces. Both weakly nonlinear pulse and harmonic responses are calculated and the general properties of the spectral and temporal structure of the scattered field are discussed. The exact strongly nonlinear solutions are derived for a special type of stress-strain relationship corresponding to the behavior of real condensed media under strong load. Profiles and spectra shown are in conformity with experimental results. The pulse response on the short delta-pulse shaped incident wave is calculated for arbitrary nonlinear properties of the layer. The possibilities to apply the sets of data on measured characteristics of pulse response in the solution of inverse problems are briefly discussed.

  • 68.
    Heldner, Mattias
    KTH, School of Computer Science and Communication (CSC), Speech, Music and Hearing, TMH, Speech Communication and Technology.
    Detection thresholds for gaps, overlaps, and no-gap-no-overlaps2011In: Journal of the Acoustical Society of America, ISSN 0001-4966, E-ISSN 1520-8524, Vol. 130, no 1, p. 508-513Article in journal (Refereed)
    Abstract [en]

    Detection thresholds for gaps and overlaps, that is acoustic and perceived silences and stretches of overlapping speech in speaker changes, were determined. Subliminal gaps and overlaps were categorized as no-gap-no-overlaps. The established gap and overlap detection thresholds both corresponded to the duration of a long vowel, or about 120 ms. These detection thresholds are valuable for mapping the perceptual speaker change categories gaps, overlaps, and no-gap-no-overlaps into the acoustic domain. Furthermore, the detection thresholds allow generation and understanding of gaps, overlaps, and no-gap-no-overlaps in human-like spoken dialogue systems.

  • 69.
    Hellgren, Johan
    et al.
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Neuroscience and Locomotion, Technical Audiology.
    Lunner, Thomas
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Neuroscience and Locomotion, Technical Audiology.
    Arlinger, Stig
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Neuroscience and Locomotion, Technical Audiology.
    System identification of feedback in hearing aids.1999In: Journal of the Acoustical Society of America, ISSN 0001-4966, E-ISSN 1520-8524, Vol. 105, p. 3481-3496Article in journal (Refereed)
  • 70.
    Hellgren, Johan
    et al.
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Neuroscience and Locomotion, Technical Audiology.
    Lunner, Thomas
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Neuroscience and Locomotion, Technical Audiology.
    Arlinger, Stig
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Neuroscience and Locomotion, Technical Audiology.
    Variations in the feedback of hearing aids.1999In: Journal of the Acoustical Society of America, ISSN 0001-4966, E-ISSN 1520-8524, Vol. 106, p. 2821-2833Article in journal (Refereed)
  • 71. Heo, Yong-Ho
    et al.
    Ih, Jeong-Guon
    Bodén, Hans
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Marcus Wallenberg Laboratory MWL.
    Acoustic source identification of an axial fan in a duct considering the rotation effect2016In: Journal of the Acoustical Society of America, ISSN 0001-4966, E-ISSN 1520-8524, Vol. 140, no 1, p. 145-156Article in journal (Refereed)
    Abstract [en]

    For developing the quiet axial fans, the spatial distribution of acoustic source parameters over the source plane provides essential information. In this study, the previously suggested source identification technique by authors is newly applied to an axial fan. To obtain the acoustic source parameters in a duct, one should overcome many technical difficulties related with: the turbulent flow, high order modes, rotating sources, inverse estimation. Measurements are conducted with several arrays of flush mounted microphones deployed on the periphery of the duct wall. A reference trigger signal obtained from the rotating blade is used to suppress the effect of turbulent flow in the measured pressure spectra with a reduction of about 25 dB in the present work. The maximum error between measurement and estimation is generally <-20 dB in the measurement plane in the very vicinity to the source. The visualized source images clearly indicate the locations and the strengths of main contributors to the radiated sound, e.g., for the inlet of the axial fan, the tip clearance between fan blades and shroud wall.

  • 72. Herbst, Christian T.
    et al.
    Ternström, Sten
    KTH, School of Computer Science and Communication (CSC), Speech, Music and Hearing, TMH, Music Acoustics.
    Svec, Jan G.
    Investigation of four distinct glottal configurations in classical singing-A pilot study2009In: Journal of the Acoustical Society of America, ISSN 0001-4966, E-ISSN 1520-8524, Vol. 125, no 3, p. EL104-EL109Article in journal (Refereed)
    Abstract [en]

    This study investigates four qualities of singing voice in a classically trained baritone: "naive falsetto," "countertenor falsetto," "lyrical chest" and "full chest." Laryngeal configuration and vocal fold behavior in these qualities were studied using laryngeal videostroboscopy, videokymography, electroglottography, and sound spectrography. The data suggest that the four voice qualities were produced by independently manipulating mainly two laryngeal parameters: (1) the adduction of the arytenoid cartilages and (2) the thickening of the vocal folds. An independent control of the posterior adductory muscles versus the vocalis muscle is considered to be the physiological basis for achieving these singing voice qualities.

  • 73.
    Häggblad, Jon
    et al.
    KTH, School of Computer Science and Communication (CSC), Numerical Analysis, NA (closed 2012-06-30).
    Engquist, Björn
    University of Texas.
    Consistent modeling of boundaries in acoustic finite-difference time-domain simulations2012In: Journal of the Acoustical Society of America, ISSN 0001-4966, E-ISSN 1520-8524, Vol. 132, no 3, p. 1303-1310Article in journal (Refereed)
    Abstract [en]

    The finite-difference time-domain method is one of the most popular for wave propagation in the time domain. One of its advantages is the use of a structured staggered grid, which makes it simple and efficient on modern computer architectures. A drawback however is the difficulty in approximating oblique boundaries, having to resort to staircase approximations.  In many scattering problems this means that the grid resolution required to obtain an accurate solution is much higher than what is dictated by propagation in a homogeneous material.  In this paper zero boundary data is considered, first for the velocity and then the pressure. These two forms of boundary conditions model perfectly rigid and pressure-release boundaries, respectively.  A simple and efficient method to consistently model curved rigid boundaries in two dimensions was developed in [A.-K. Tornberg and B. Engquist, J. Comput. Phys. 227, 6922--6943 (2008)].  Here this treatment is generalized to three dimensions.  Based on the approach of this method, a technique to model pressure-release surfaces with second order accuracy and without additional restriction on the timestep is also introduced.  The structure of the standard method is preserved, making it easy to use in existing solvers.  The effectiveness is demonstrated in several numerical tests.

  • 74.
    Håkansson, Bo
    et al.
    Chalmers University of Technology.
    Brandt, Anders
    Chalmers University of Technology.
    Carlsson, Peder
    Chalmers University of Technology.
    Tjellström, Anders
    ENT Department, Sahlgrenska Hospital.
    Resonance frequencies of the human skull in vivo1994In: Journal of the Acoustical Society of America, ISSN 0001-4966, E-ISSN 1520-8524, Vol. 95, no 3, p. 1474-1481Article in journal (Refereed)
    Abstract [en]

    Patients with skin penetrating titanium implants in the temporal bone, for attachment of bone-anchored hearing aids, have made it possible to investigate the free-damped natural frequencies (resonance frequencies) of the human skull in vivo. The resonance frequencies of the skull of six subjects were investigated. Teh resonance frequencies were extracted from two frequency response functions (acceleration/force) measured on each subject: One point measurement where the force and acceleration were both measured at the same point, and one transcranial measurement where the acceleration was measured contralaterally. Between 14 and 19 resonance frequencies were identified for each subject in the frequency range 500 Hz to 7.5 kHz. The two lowest resonance frequencies were found to be on the average 972 (range 828-1164) and 1230 (range 981-1417) Hz. The relative damping coefficients of all resonances were found to be between 2.6 and 8.9%. Due to the relatively high damping coefficients, it is assumed that the resonance frequencies do not significantly affect bone conducted sound. In the transcranial measurements, however, a few large antiresonances were found which may affect bone-conducted sound. Intersubject variations were large, probably due to individual variations in skull geometry and in mechanical parameters. The results were shown to be consistent with previous results obtained on dry skulls. No obvious correlation between lowest resonance frequency and skull size was found.

  • 75.
    Håkansson, Bo
    et al.
    Chalmers.
    Carlsson, Peder
    Chalmers.
    Brandt, Anders
    Chalmers.
    Stenfelt, Stefan
    Linköping University, Department of Clinical and Experimental Medicine, Technical Audiology . Linköping University, Faculty of Health Sciences.
    Linearity of sound propagation through the human skull in vivo1996In: Journal of the Acoustical Society of America, ISSN 0001-4966, E-ISSN 1520-8524, Vol. 99, no 4, p. 2239-2243Article in journal (Refereed)
  • 76.
    Håkansson, Bo
    et al.
    Chalmers University of Technology.
    Carlsson, Peder
    Chalmers University of Technology.
    Brandt, Anders
    Chalmers University of Technology.
    Stenfelt, Stefan
    Chalmers University of Technology.
    Linearity of sound transmission through the human skull in vivo1996In: Journal of the Acoustical Society of America, ISSN 0001-4966, E-ISSN 1520-8524, Vol. 99, no 4, p. 2239-2243Article in journal (Refereed)
    Abstract [en]

    The linearity of sound propagation through the human skull was investigated. One male subject, equipped with bilateral skin-penetrating titanium fixtures for attachment of bone-anchored hearing aids, was studied thoroughly. Three different methods were used: comparison of the frequency response functions estimated at different signal levels (using stepped sine as well as random noise), comparison of the coherence function at different signal levels (using random noise), and the Hilbert transform of the estimated frequency response function. Frequencies from 0.1 to 10 kHz and signal levels up to 77 dB HL at discrete frequencies were used. No indication of any significant nonlinear behavior was found with the three methods used.

  • 77.
    Janssen, S.A.
    et al.
    Department of Urban Environment and Safety, Netherlands Organization for Applied Scientific Research, P.O. Box 49, 2600 AA Delft, Netherlands.
    Vos, H.
    Department of Urban Environment and Safety, Netherlands Organization for Applied Scientific Research, P.O. Box 49, 2600 AA Delft, Netherlands.
    Eisses, A.R.
    Department of Acoustics and Sonar, Netherlands Organization for Applied Scientific Research, P.O. Box 96864, 2509 JG The Hague, Netherlands.
    Pedersen, Eja
    Halmstad University, School of Business, Engineering and Science, Biological and Environmental Systems (BLESS), Ecology and Environmental Science.
    A comparison between exposure-response relationships for wind turbine annoyance and annoyance due to other sources2011In: Journal of the Acoustical Society of America, ISSN 0001-4966, E-ISSN 1520-8524, Vol. 130, no 6, p. 3746-3753Article in journal (Refereed)
    Abstract [en]

    Surveys have shown that noise from wind turbines is perceived as annoying by a proportion of residents living in their vicinity, apparently at much lower noise levels than those inducing annoyance due to other environmental sources. The aim of the present study was to derive the exposure-response relationship between wind turbine noise exposure in L(den) and the expected percentage annoyed residents and to compare it to previously established relationships for industrial noise and transportation noise. In addition, the influence of several individual and situational factors was assessed. On the basis of available data from two surveys in Sweden (N=341, N=754) and one survey in the Netherlands (N=725), a relationship was derived for annoyance indoors and for annoyance outdoors at the dwelling. In comparison to other sources of environmental noise, annoyance due to wind turbine noise was found at relatively low noise exposure levels. Furthermore, annoyance was lower among residents who received economical benefit from wind turbines and higher among residents for whom the wind turbine was visible from the dwelling. Age and noise sensitivity had similar effects on annoyance to those found in research on annoyance by other sources

  • 78.
    Jansson, Erik V.
    et al.
    Kungliga tekniska högskolan, KTH.
    Molin, Nils-Erik
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Fluid and Experimental Mechanics.
    Optical modal analysis compared to modal analysis with digital electronic equipment1988In: Journal of the Acoustical Society of America, ISSN 0001-4966, E-ISSN 1520-8524, Vol. 84, no 1, p. 136-Article in journal (Refereed)
    Abstract [en]

    Hologram interferometry and speckle interferometry have introduced powerful tools for "optical modal analysis." The vibration amplitudes at a single frequency are recorded simultaneously for all points of a surface. The excitation position and frequency are adjusted to give a normal mode by watching the vibration patterns in real time. In the common modal analysis with digital electronic equipment, the vibrations of a single point as a function of time are recorded for all frequencies simultaneously via the impulse response. Impulse responses for a large number of points are measured, analyzed, and recalculated to extract the normal modes. Investigations of two modes of a complicated object (a violin) using both methods showed differences. The position of the dominating antinodes agreed, but the distribution of the vibration amplitudes and especially the nodal lines did not always agree. The differences seem to depend mainly on methods. The differences imply that great cautiousness is motivated in interpreting unknown vibration modes of objects with complicated structures and boundaries. The real time observation with the optical modal analysis offers hereby advantages

  • 79.
    Jansson, E.V.
    et al.
    Kungliga tekniska högskolan, KTH.
    Molin, Nils-Erik
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Fluid and Experimental Mechanics.
    Saldner, Henrik O.
    Luleå tekniska universitet.
    On eigenmodes of the violin: electronic holography and admittance measurements1994In: Journal of the Acoustical Society of America, ISSN 0001-4966, E-ISSN 1520-8524, Vol. 95, no 2, p. 1100-1105Article in journal (Refereed)
    Abstract [en]

    The present experimental investigation, using recently assembled advanced electro-optical equipment for vibration analysis of three violins, was conducted to seek answers to three questions. A general or global question: Which parts of the violin body are vibrating the most? And two questions related to tonal quality: Are basic low-frequency vibration modes of a musically superior instrument different from those of an inferior violin? Can some special vibration properties be found to support the ``bridge hill?'' Optically obtained vibration modes were recorded as well as frequency responses in the form of admittance measurements. The investigation showed that the vibration modes found earlier are representative both for the inferior violin and the musically superior instruments, although discrepancies can be seen, both in eigenmode shapes and admittance responses. The experimental results are also in quite good agreement with published results of the modal analysis of a violin. Further, the experimental results indicate that the transversal vibrations are mainly within the plates, but at low frequencies, the vibrations of the edges and of the ribs can be large and in-plane as well as transversal. At higher frequencies, the transversal vibration amplitudes are small at the plate edges and larger inside. The top plate tends to have the largest amplitude of vibrations. In the 2.5-kHz range the violin with the most clear ``bridge hill'' tends to have the largest vibrations of the plates.

  • 80.
    Jiang, Biao
    Hangzhou Applied Acoustics Research Institute.
    Robust wideband adaptive beamforming using waveguide invariant focusing method2012In: Journal of the Acoustical Society of America, ISSN 0001-4966, E-ISSN 1520-8524, Vol. 131, no 4, p. 3487-Article in journal (Refereed)
    Abstract [en]

    The waveguide invariant describing the dispersive propagation in underwater environment can provide useful information for signal processing. In this paper, waveguide invariant focusing is exploited to preprocess the received horizontal array signal, such that the moving target is aligned in a single rank-one signal subspace over the bandwidth, results a reduction of the number of the snapshots necessary for the adaptive beamforming, and the diagonal loading is optimized using the robust Capon method to further improve the robustness. Numerical results show that the proposed method can improve the detection performance with limited observation time. Moreover, passive ranging is accomplished when the beamforming output achieves the maximum over a scanned target range limit.

  • 81.
    Johansson, Örjan
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Lindegren, David
    Luleå tekniska universitet.
    Analysis of everyday sounds which are extremely annoying for children with autism2008In: Journal of the Acoustical Society of America, ISSN 0001-4966, E-ISSN 1520-8524, Vol. 123, no 5, p. 3299-Article in journal (Other academic)
    Abstract [en]

    Extreme sensitivity to noise is a problem that almost all autistic children suffer from. A sound that is extremely annoying does not need to be loud. However, the characteristics and temporal variations of these sounds are sparsely investigated. The aim of this study is to increase the knowledge about these extremely annoying sounds so they can be avoided by better design criteria for classrooms and venues like that. By interviewing teachers and parents a number of everyday sounds were identified and binaurally recorded. Examples are vacuum cleaners, ventilation noise, washing machines and pouring water. Detailed psychoacoustic analyses of this type of sounds were achieved by a listening test procedure in three parts. First 16 children composed different types of vacuum cleaner sounds trying to minimize annoyance in two different tests, a) keeping original sound pressure level. b) adjusting to acceptable loudness. In the second part, teachers working with autistic children performed a listening test to evaluate some of the composed sounds from part 1 and modified versions of them. The third part was performed by children to validate the results. The results showed that Roughness, Loudness and an index defined as High frequency tonality were the most important characteristics.

  • 82.
    Jonasson, Hans
    Akustik (Eta).
    Aspects of ground effect modeling2011In: Journal of the Acoustical Society of America, ISSN 0001-4966, E-ISSN 1520-8524, Vol. 129, no 1, p. 47-53Article in journal (Refereed)
  • 83.
    Kari, Leif
    KTH, Superseded Departments, Vehicle Engineering.
    On the dynamic stiffness of preloaded vibration isolators in the audible frequency range: Modeling and experiments2003In: Journal of the Acoustical Society of America, ISSN 0001-4966, E-ISSN 1520-8524, Vol. 113, no 4, p. 1909-1921Article in journal (Refereed)
    Abstract [en]

    The nonlinear, preload-dependent dynamic stiffness of a cylindrical vibration isolator is examined via measurements and modeling within an audible frequency range covering 50 to 1000 Hz at various preloads. The stiffness is found to depend strongly on frequency-resulting in peaks and troughs, and on preload-particularly above 500 Hz. The problems of simultaneously modeling the rubber prestrain dependence and its audible short-term response are removed by adopting a nearly incompressible material model, being elastic in dilatation while displaying viscoelasticity in deviation. The latter exhibits a time strain separable relaxation tensor with a single function embodying its time dependence. This function is based on a continuous fractional order derivative model, the main advantage being the minimum number of parameters required to successfully model the rubber properties over a broad structure-borne sound frequency domain, while embodying a continuous distribution of relaxation time. The weak formulations corresponding to the stiffness problem are solved by an updated Lagrangian nonlinear finite-element procedure. The model and measurement results agree strikingly well with static and dynamic measurements throughout the whole frequency domain for the examined preloads.

  • 84.
    Karlsson, Mikael
    et al.
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, MWL Flow acoustics.
    Glav, Ragnar
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Marcus Wallenberg Laboratory MWL.
    Åbom, Mats
    KTH, School of Engineering Sciences (SCI), Centres, Linné Flow Center, FLOW.
    The Herschel-Quincke tube: The attenuation conditions and their sensitivity to mean flow2008In: Journal of the Acoustical Society of America, ISSN 0001-4966, E-ISSN 1520-8524, Vol. 124, no 2, p. 723-732Article in journal (Refereed)
    Abstract [en]

    The classic Herschel-Quincke tube is a parallel connection of two ducts yielding multiple noise attenuation maxima via destructive interference. This problem has been discussed to different degrees by a number of authors over the years. This study returns to the basics of the system for the purpose of furthering the understanding of the conditions necessary for noise attenuation and especially their sensitivity to mean flow. First, the transmission loss for an N-duct system with mean flow and arbitrary conditions of state in the different ducts is derived. Next, the two types of conditions yielding the attenuation maxima are studied. In addition to a discussion of the underlying physics, generic expressions for frequencies at which maximum attenuation occur are presented. Experiments without mean flow generally show good agreement with theory based on straight duct elements. However, more detailed models may be required for accurate simulations in the presence of mean flow. A simple model compensating for the losses associated with bends is shown to improve the results significantly for the geometry studied.

  • 85.
    Keus van de Poll, Marijke
    et al.
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering, Environmental psychology.
    Carlsson, Johannes
    Chalmers University of Technology.
    Marsh, John
    School of Psychology, University of Central Lancashire, Preston, UK.
    Ljung, Robert
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering, Environmental psychology.
    Odelius, Johan
    Luleå University of Technology.
    Schlittmeier, Sabine
    Catholic University of Eichstätt-Ingolstadt, Eichstätt, Germany .
    Sundin, Gunilla
    Norconsult AB, Stockholm, Sweden.
    Sörqvist, Patrik
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering, Environmental psychology.
    Unmasking the effects of masking on performance: the potential of multiple-voice masking in the office environment2015In: Journal of the Acoustical Society of America, ISSN 0001-4966, E-ISSN 1520-8524, Vol. 138, no 2, p. 807-816Article in journal (Refereed)
    Abstract [en]

    Broadband noise is often used as a masking sound to combat the negative consequences of background speech on performance in open-plan offices. As office workers generally dislike broadband noise, it is important to find alternatives that are more appreciated while being at least not less effective. The purpose of experiment 1 was to compare broadband noise with two alternatives—multiple voices and water waves—in the context of a serial short-term memory task. A single voice impaired memory in comparison with silence, but when the single voice was masked with multiple voices, performance was on level with silence. Experiment 2 explored the benefits of multiple-voice masking in more detail (by comparing one voice, three voices, fivevoices, and seven voices) in the context of word processed writing (arguably a more office-relevant task). Performance (i.e., writing fluency) increased linearly from worst performance in the one-voice condition to best performance in the seven-voice condition. Psychological mechanisms underpinning these effects are discussed.

  • 86.
    Kierkegaard, Axel
    et al.
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Marcus Wallenberg Laboratory MWL.
    Boij, Susann
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Marcus Wallenberg Laboratory MWL. KTH, School of Engineering Sciences (SCI), Centres, VinnExcellence Center for ECO2 Vehicle design.
    Efraimsson, Gunilla
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Aeroacoustics. KTH, School of Engineering Sciences (SCI), Centres, Linné Flow Center, FLOW.
    A frequency domain linearized Navier-Stokes equations approach to acoustic propagation in flow ducts with sharp edges2010In: Journal of the Acoustical Society of America, ISSN 0001-4966, E-ISSN 1520-8524, Vol. 127, no 2, p. 710-719Article in journal (Refereed)
    Abstract [en]

    Acoustic wave propagation in flow ducts is commonly modeled with time-domain non-linear Navier-Stokes equation methodologies. To reduce computational effort, investigations of a linearized approach in frequency domain are carried out. Calculations of sound wave propagation in a straight duct are presented with an orifice plate and a mean flow present. Results of transmission and reflections at the orifice are presented on a two-port scattering matrix form and are compared to measurements with good agreement. The wave propagation is modeled with a frequency domain linearized Navier-Stokes equation methodology. This methodology is found to be efficient for cases where the acoustic field does not alter the mean flow field, i.e., when whistling does not occur.

  • 87.
    Kjems, Ulrik
    et al.
    Oticon AS, Smørum, Denmark .
    Boldt, Jesper B
    Oticon AS, Smørum, Denmark .
    Pedersen, Michael S
    Oticon AS, Smørum, Denmark .
    Lunner, Thomas
    Linköping University, Department of Clinical and Experimental Medicine, Technical Audiology. Linköping University, Faculty of Health Sciences. Oticon Research Centre Eriksholm, Snekkersten, Denmark.
    Wang, DeLiang
    Ohio State University, Columbus, USA.
    Role of mask pattern in intelligibility of ideal binary-masked noisy speech2009In: Journal of the Acoustical Society of America, ISSN 0001-4966, E-ISSN 1520-8524, Vol. 126, no 3, p. 1415-1426Article in journal (Refereed)
    Abstract [en]

    Intelligibility of ideal binary masked noisy speech was measured on a group of normal hearing individuals across mixture signal to noise ratio (SNR) levels, masker types, and local criteria for forming the binary mask. The binary mask is computed from time-frequency decompositions of target and masker signals using two different schemes: an ideal binary mask computed by thresholding the local SNR within time-frequency units and a target binary mask computed by comparing the local target energy against the long-term average speech spectrum. By depicting intelligibility scores as a function of the difference between mixture SNR and local SNR threshold, alignment of the performance curves is obtained for a large range of mixture SNR levels. Large intelligibility benefits are obtained for both sparse and dense binary masks. When an ideal mask is dense with many ones, the effect of changing mixture SNR level while fixing the mask is significant, whereas for more sparse masks the effect is small or insignificant.

  • 88.
    Koelewijn, Thomas
    et al.
    VU University Medical Cente, Amsterdam, Netherlands .
    Zekveld, Adriana
    Linköping University, Department of Behavioural Sciences and Learning, Disability Research. Linköping University, Faculty of Arts and Sciences.
    Festen, Joost M.
    VU University Medical Cente, Amsterdam, Netherlands.
    Kramer, Sophia E.
    VU University Medical Cente, Amsterdam, Netherlands.
    The influence of informational masking on speech perception and pupil response in adults with hearing impairment2014In: Journal of the Acoustical Society of America, ISSN 0001-4966, E-ISSN 1520-8524, Vol. 135, no 3, p. 1596-1606Article in journal (Refereed)
    Abstract [en]

    A recent pupillometry study on adults with normal hearing indicates that the pupil response during speech perception (cognitive processing load) is strongly affected by the type of speech masker. The current study extends these results by recording the pupil response in 32 participants with hearing impairment (mean age 59 yr) while they were listening to sentences masked by fluctuating noise or a single-talker. Efforts were made to improve audibility of all sounds by means of spectral shaping. Additionally, participants performed tests measuring verbal working memory capacity, inhibition of interfering information in working memory, and linguistic closure. The results showed worse speech reception thresholds for speech masked by single-talker speech compared to fluctuating noise. In line with previous results for participants with normal hearing, the pupil response was larger when listening to speech masked by a single-talker compared to fluctuating noise. Regression analysis revealed that larger working memory capacity and better inhibition of interfering information related to better speech reception thresholds, but these variables did not account for inter-individual differences in the pupil response. In conclusion, people with hearing impairment show more cognitive load during speech processing when there is interfering speech compared to fluctuating noise. (C) 2014 Acoustical Society of America.

  • 89.
    Koniaris, Christos
    et al.
    KTH, School of Electrical Engineering (EES), Sound and Image Processing.
    Kuropatwinski, Marcin
    KTH, School of Electrical Engineering (EES), Sound and Image Processing.
    Kleijn, Bastiaan
    KTH, School of Electrical Engineering (EES), Sound and Image Processing.
    Auditory-model based robust feature selection for speech recognition2010In: Journal of the Acoustical Society of America, ISSN 0001-4966, E-ISSN 1520-8524, Vol. 127, no 2, p. EL73-EL79Article in journal (Refereed)
    Abstract [en]

     It is shown that robust dimension-reduction of a feature set for speech recognition can be based on a model of the human auditory system. Whereas conventional methods optimize classification performance, the proposed method exploits knowledge implicit in the auditory periphery, inheriting its robustness. Features are selected to maximize the similarity of the Euclidean geometry of the feature domain and the perceptual domain. Recognition experiments using mel-frequency cepstral coefficients (MFCCs) confirm the effectiveness of the approach, which does not require labeled training data. For noisy data the method outperforms commonly used discriminant-analysis based dimension-reduction methods that rely on labeling. The results indicate that selecting MFCCs in their natural order results in subsets with good performance.

  • 90.
    Larsson, Conny
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, LUVAL.
    Öhlund, Olof
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, LUVAL.
    Amplitude modulation of sound from wind turbines under various meteorological conditions2014In: Journal of the Acoustical Society of America, ISSN 0001-4966, E-ISSN 1520-8524, Vol. 135, no 1, p. 67-73Article in journal (Refereed)
    Abstract [en]

    Wind turbine (WT) sound annoys some people even though the sound levels are relatively low. This could be because of the amplitude modulated “swishing” characteristic of the turbine sound,which is not taken into account by standard procedures for measuring average sound levels. Studies of sound immission from WTs were conducted continually between 19 August 2011 and 19 August 2012 at two sites in Sweden. A method for quantifying the degree and strength of amplitude modulation (AM) is introduced here. The method reveals that AM at the immission points occur under specific meteorological conditions. For WT sound immission, the wind direction and sound speed gradient are crucial for the occurrence of AM. Interference between two or more WTs could probably enhance AM. The mechanisms by which WT sound is amplitude modulated are not fully understood.

  • 91.
    Larsson, Elisabeth
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Division of Scientific Computing. Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Numerical Analysis.
    Abrahamsson, Leif
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Division of Scientific Computing. Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Numerical Analysis.
    Helmholtz and parabolic equation solutions to a benchmark problem in ocean acoustics2003In: Journal of the Acoustical Society of America, ISSN 0001-4966, E-ISSN 1520-8524, Vol. 113, p. 2446-2454Article in journal (Refereed)
  • 92.
    Leander, Johan L.
    Swedish National Defence College, Department of Military Studies, Military-Technology Division.
    A note on transient underwater bubble sound1998In: Journal of the Acoustical Society of America, ISSN 0001-4966, E-ISSN 1520-8524, Vol. 103, no 2, p. 1205-1208Article in journal (Refereed)
    Abstract [en]

    This Letter considers scattered sound from transiently oscillating gas bubbles in liquids. The full transient problem including the finite duration of the excitation is analyzed. As a result, the wave front of the radiated sound pulse involving information about the excitation is also studied. The model presented is used to simulate sound pulses from sea-surface bubbles which have been generated by, for example, spilling breakers, capillary-gravity waves, and rain drops. Although very simple in relation to the actual physical process of excitation, this model enables us to predict some of the essential properties of scattered pulses observed experimentally. It is suggested that the time scale of duration of the initial driving that enters into the present analysis might be of some use in a further physical understanding of bubble generation and excitation.

  • 93. Leander, Johan L.
    Comments on "Acoustic dispersion and attenuation in many spherical scatterer systems and the Kramers-Kronig relations"1998In: Journal of the Acoustical Society of America, ISSN 0001-4966, E-ISSN 1520-8524, Vol. 104, no 2, p. 1111-1114Article in journal (Refereed)
    Abstract [en]

    The aim of this Comment is to suggest some possible improvements and developments of the investigation by Zhen Ye [J. Acoust. Sec. Am. 101, 3299-3305 (1997)]. Particular attention is given to the causality concept and the use of integral theorems.

  • 94.
    Leander, Johan L.
    Swedish National Defence College, Department of Military Studies, Military-Technology Division.
    On the eigenfrequency of a gas bubble in a liquid1997In: Journal of the Acoustical Society of America, ISSN 0001-4966, E-ISSN 1520-8524, Vol. 102, no 3, p. 1900-1903Article in journal (Refereed)
    Abstract [en]

    This investigation concerns free linear gas bubble oscillations in liquids. Of prime interest is the eigenfrequency, and in particular its real part, here named as the transient frequency. The conceptual difference between the more frequently consulted resonance frequency and the transient frequency is first addressed by means of the classical mechanical oscillator. Next, bubble pulsations in liquids are discussed and an existing model is used for the gas-liquid interaction from which an approximate expression for the eigenfrequency is derived. A rationale for the approximate evaluation of the functions modeling the thermal processes is suggested which is independent of the frequency content of any possible pressure excitation, Moreover, compressibility effects are not approximated in the derivation presented here, The quantitative difference between the adiabatic resonance frequency and the derived estimate of the transient frequency is found to be of significance for small bubbles. Finally, the similarity between a standard mechanical oscillator and a bubble in a liquid for the case of liquid-compressibility effects only is discussed.

  • 95.
    Leander, Johan L.
    Swedish National Defence College, Department of Military Studies, Military-Technology Division.
    On the relation between the wavefront speed and the group velocity concept1996In: Journal of the Acoustical Society of America, ISSN 0001-4966, E-ISSN 1520-8524, Vol. 100, no 6, p. 3503-3507Article in journal (Refereed)
    Abstract [en]

    The relation between the wavefront speed and the group velocity concept is studied in this work. The relationship between the more well-known velocity concept named as the phase velocity and the speed of propagation of a front of an acoustic pulse is discussed. This is of interest since it concerns transient wave propagation and is, in general, not well known. The form and properties of a pulse can be obtained by means of a Fourier integral and estimates based on quantities derived for monochromatic waves, such as the phase velocity, can be severely misleading and confusing. The wavefront velocity is defined as the high-frequency Limit of the phase velocity. This quantity can be far less than the value of the phase velocity for finite frequencies which for example is the case for bubbly fluids. Then the group velocity concept is discussed, which was introduced in order to characterize the propagation of water waves of essentially the same wavelength. However, more confusion occurs in that it is sometimes believed that a wavefront is propagating with the group velocity (a limit process not mentioned) since it can be related to the propagation of energy. This interpretation of energy propagation is based on sinusoidal waves and involves time as well as space averages and is not applicable for pulses. However, by means of the expression for the group velocity given by Stokes it is shown that the speed of a wavefront can be found from the group velocity at a limiting high frequency. This result can be understood geometrically from the definition of the group velocity given by Lamb which is conservation of wavelength. A wavefront is a discontinuity and limiting short wavelengths will be found there.

  • 96. Leander, Johan L.
    Wavefront and group velocity in relaxing and bubbly fluids1999In: Journal of the Acoustical Society of America, ISSN 0001-4966, E-ISSN 1520-8524, Vol. 105, no 6, p. 3044-3048Article in journal (Refereed)
    Abstract [en]

    In this paper it is demonstrated that a theoretical model for wave propagation may indeed correspond to a well-posed transient problem although the group velocity for finite frequencies becomes greater than the high frequency limit of the phase velocity, negative or even infinite. Sufficient conditions for causality dare derived and the particular cases of relaxing and bubbly fluids are considered so as to show-some of the properties of the group velocity concept.

  • 97. Lehtonen, Heidi-Maria
    et al.
    Askenfelt, Anders
    KTH, School of Computer Science and Communication (CSC), Speech, Music and Hearing, TMH, Music Acoustics.
    Valimaki, Vesa
    Analysis of the part-pedaling effect in the piano2009In: Journal of the Acoustical Society of America, ISSN 0001-4966, E-ISSN 1520-8524, Vol. 126, no 2, p. EL49-EL54Article in journal (Refereed)
    Abstract [en]

    This letter reports basic acoustic phenomena related to part-pedaling in the piano. With part-pedaling, the piano tone can be divided into three distinct time intervals: initial free vibration, damper-string interaction, and final free vibration. Varying the distance of the damper from the string, the acoustic signal and the damper acceleration were measured for several piano tones. During the damper-string interaction, the piano tone decay is rapid and the timbre of the tone is affected by the nonlinear amplitude limitation of the string motion. During the final free decay, the string continues to vibrate freely with a lower decay rate.

  • 98.
    Lidestam, Björn
    et al.
    Linköping University, Department of Behavioural Sciences and Learning, Psychology. Linköping University, Faculty of Arts and Sciences.
    Moradi, Shahram
    Linköping University, Department of Behavioural Sciences and Learning, Disability Research. Linköping University, Faculty of Arts and Sciences.
    Pettersson, Rasmus
    Linköping University, Department of Clinical and Experimental Medicine, Division of Neuroscience. Linköping University, Faculty of Health Sciences.
    Ricklefs, Theodor
    Linköping University, Department of Clinical and Experimental Medicine, Division of Neuroscience. Linköping University, Faculty of Health Sciences.
    Audiovisual training is better than auditory-only training for auditory-only speech-in-noise identification2014In: Journal of the Acoustical Society of America, ISSN 0001-4966, E-ISSN 1520-8524, Vol. 136, no 2, p. EL142-EL147Article in journal (Refereed)
    Abstract [en]

    The effects of audiovisual versus auditory training for speech-in-noise identification were examined in 60 young participants. The training conditions were audiovisual training, auditory-only training, and no training (n = 20 each). In the training groups, gated consonants and words were presented at 0 dB signal-to-noise ratio; stimuli were either audiovisual or auditory-only. The no-training group watched a movie clip without performing a speech identification task. Speech-in-noise identification was measured before and after the training (or control activity). Results showed that only audiovisual training improved speech-in-noise identification, demonstrating superiority over auditory-only training.

  • 99.
    Lind Nordgren, Eleonora
    et al.
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Marcus Wallenberg Laboratory MWL. KTH, School of Engineering Sciences (SCI), Centres, VinnExcellence Center for ECO2 Vehicle design.
    Göransson, Peter
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Marcus Wallenberg Laboratory MWL. KTH, School of Engineering Sciences (SCI), Centres, VinnExcellence Center for ECO2 Vehicle design.
    Deü, Jean-Francois
    National Conservatory of Arts and Crafts, Laboratoire de Mécanique des Structures et des Systémes Couplés (LMSSC), Conservatoire National des Arts et Metiérs, France.
    Dazel, Olivier
    University of Maine, Laboratoire d'Acoustique de l'Université du Maine, France.
    Vibroacoustic response sensitivity due to relative alignment of two anisotropic poro-elastic layers2013In: Journal of the Acoustical Society of America, ISSN 0001-4966, E-ISSN 1520-8524, Vol. 133, no 5, p. EL426-EL430Article in journal (Refereed)
    Abstract [en]

    The effects of relative alignment of two different types of anisotropic open cell porous materials are investigated in terms of the acoustic response of a multi-layered configuration. Numerical experiments, where gradient based optimization techniques were used, are conducted to find possible extremal values. It is shown that, depending on the degree of anisotropy of the porous material properties, their angular orientations have a significant and frequency dependent influence on the measured response. The results highlight the importance of further advancing the knowledge of anisotropic porous material behavior.

  • 100. Ling, Jun
    et al.
    He, Hao
    Li, Jian
    Roberts, William
    Stoica, Peter
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Division of Systems and Control. Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Automatic control.
    Covert underwater acoustic communications2010In: Journal of the Acoustical Society of America, ISSN 0001-4966, E-ISSN 1520-8524, Vol. 128, no 5, p. 2898-2909Article in journal (Refereed)
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