Mask-less oral and nasal audio recording and air flow estimation for speech analysis
Here is demonstrated Rivener, a mask-less oral and nasal audio recorder and air flow estimation system. This system records audio and low-frequency pseudo-sound from the nares and mouth. The system does not interfere with speech intelligibility, and minimally interferes with visual observation of the speaker. From these recordings, nasalance (a ratio of oral and nasal sound energy), oral air flow, and nasal air flow patterns may be estimated, all while allowing effective clinical observation. The first demonstration is a case-study comparison of the difference between hearing-impaired (HI) speech and non-impaired (NI) speech. Rivener records standard features of HI speech such as: (i) Atypically high or low speech amplitude; (ii) fundamental frequency (pitch) making individual words into intonational phrases; (iii) speech segment substitution; (iv) hypernasa-lance; (v) atypical air flow in HI speech, including low air flow during plosive release. The second demonstration is a comparison of Rivener and the Rothenberg NAS-1's ability to record nasalance among 26 New Zealand English speakers. The NAS-1 can differentiate low, medium, and high nasalance passages, whereas Rivener differentiates only medium and high nasalance passages consistently.