Pulmonic ingressive speech is often mentioned anecdotally in the linguistic research. Most previous studies investigating the phenomenon have stressed the paralinguistic function of ingressive speech (IS).

This paper studies IS in two corpora of spontaneous Swedish speech. Eight subjects made business travel bookings in two data collections. In one corpus the subjects talked with a real, human travel agent; in the other theyspoke with what they believed was a computer, played by a professional actor. The results show that all subjects made use of IS in the human–human setting, while no one used IS in the human–machine setting.

These results strengthen the notion that IS is a speech phenomenon that is truly associated with human interactions. The results are discussed from the perspective of possible underlying factors, including discourse structure, gender issues, and possible enhancements in automatic speech-based dialog systems.