Portable Photoglottography for Monitoring Vocal Fold Vibrations in Speech Production

Photoglottography (PGG) is an effective method to monitor vocal fold vibrations via measuring light transmission across the glottis. The difficulty in operation however limits its wide use in speech studies. This paper is to realize a portable PGG (P-PGG) module with an audio interface to record glottal and speech waveforms simultaneously with ease. Near Infrared (NIR) LEDs are driven as a light source and an extremely high-gain photodetector circuit is employed. The output PGG signal is subsequently band-pass filtered and amplified for recording. The whole system is minimized, battery powered with well-controlled heat radiation. In experiments, P-PGG, EGG and microphone are worn together by speakers. The results verify that the NIR lighting P-PGG is successful at recording complete information of glottal cycles in comparison to EGG. Thus, the P-PGG is an effective method for investigating phonation types and consonant-vowel interactions in speech.