Laryngoaltimeter: a new ambulatory device for laryngeal height control, preliminary results

The vertical larynx position has significant effects on vocal tract resonances and on the biomechanical properties of the vocal folds. It is generally agreed that the larynx should be kept in a comfortably low position during singing, and voice problems are often associated with a habitually raised larynx. A new method, and a battery operated portable device called Laryngoaltimeter, was developed to control laryngeal height continuously for therapeutic or educational purposes. Two similar condenser microphones attached on the suprasternal notch and supraglottic region were used to capture corresponding vibrations during phonation. The microphone signals were then filtered through a band pass filter (90-240 Hz), digitized, and compared to each other by detection algorithms of the Laryngoaltimeter. When the supraglottic microphone received subglottic resonance related vibrations due to laryngeal elevation, auditory and visual signals were produced as a biofeedback by the device. Waterfall amplitude spectrograms of the microphone signals verified that the frequencies captured by each microphone were dissimilar before and similar after laryngeal elevation. The accuracy of the device was found to be 87% on 13 subjects having different voice classifications as a demonstration of its use. Laryngoaltimeter is a prototype device and needs to be developed. Further research may also be established to investigate the habitual effects of keeping vertical position low by using Laryngoaltimeter as a biofeedback device during therapy exercises or voice lessons.