Laser vibrometric characterization and model development of a human vocal tract for acoustic therapy of deaf patients

Human communication is to a large extend based on the use and variation of the voice. The correct use of the vocal system is learned from childhood on by auditory feedback. Hearing-impaired people do not receive this acoustic feedback and alternative methods are used if language is to be learned in addition to other forms of communication. Resonance frequencies play a decisive role in the formation of vowels. Hearing-impaired people may not be able to hear the vowel dependent resonances; however, they might be able to feel the corresponding vibrational structure within their vocal tract. In order to elucidate this process further, we performed vibrometric measurements of 3D printed model with uniform wall thickness which was acoustically excited with via a broadband loudspeaker. The resonance frequencies in the range of 100 - 5000Hz were clearly visible and the locations of the strongest vibrations could be determined. Furthermore, vibrometric data showed specific regions, were hearing-impaired people may feel some vibrations if the vowels are supported by the vocal tract structure. Vibrometric data, such as velocity amplitudes at selected regions and frequencies could be measured.