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Automatic acoustic tests of conference phones
Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
2017 (English)Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
Abstract [en]

This master thesis was completed at Limes Audio in Umeå. Limes Audio are specialized in speech enhancement software which is mostly used in conference phones. Their software is used to reduce noise, echo cancellation as well as reduction of distortion. When a conference phone is malfunctioning it can be troublesome to find the cause of the problem. Common issues that lead to perceived poor audio quality are rattling plastics, loose parts and an environment with demanding acoustics. There is a need for automatic tests to run on conference phone which can diagnose audio quality and the acoustics of the environment where the conference phone is located in. A previous master thesis by Wilhelmsson called "Estimating Loudspeaker Distortion and Room Reverberation Time Using a Speakerphone" focused on evaluating several tests run in MATLAB for analyzing acoustic characteristics of a room. The goal of this thesis was to continue the work of the master thesis by Wilhelmsson. Previous tests served as a basis for this thesis. The tests where modified and rewritten in C and run on a Linux computer connected to a specific conference phone model.

In the extended test made in this thesis using sine sweep signals, the reverberation time as well as the distortion for the conference phone setup was determined. The calculated reverberation time was compared to the results using Room EQ Wizard and gave almost identical results.

Total harmonic distortion was not easy to relate to the perceived audio quality. There is a need to further develop methods to take into account other types of distortion than the total harmonic distortion. Rub & buzz is one kind of distortion that could be of interest. To investigate pass or fail thresholds for reverberation time as well as distortion is central for further development of this test software.

Place, publisher, year, edition, pages
2017. , 37 p.
Series
UPTEC F, ISSN 1401-5757 ; 17040
Keyword [en]
Acoustics, Digital signal processing, total harmonic distortion, reverberation
National Category
Signal Processing
Identifiers
URN: urn:nbn:se:uu:diva-326253OAI: oai:DiVA.org:uu-326253DiVA: diva2:1119420
External cooperation
Google (former Limes Audio)
Educational program
Master Programme in Engineering Physics
Supervisors
Examiners
Available from: 2017-07-04 Created: 2017-07-04 Last updated: 2017-07-04Bibliographically approved

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CiteExportLink to record
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