PNEUMOTACHOGRAPH MASK OR MOUTHPIECE COUPLING ELEMENT FOR AIRFLOW MEASUREMENT DURING SPEECH OR SINGING

A pneumotachograph mask or mouthpiece coupling element may reduce the distortion and muffling of the voice otherwise caused by a mask or mouthpiece when measuring the low-frequency components of a volume-velocity of oral or nasal airflow during speech or singing. This improved performance is accomplished by separating the low-frequency components to be measured from the higher frequency or acoustic components by an acoustic filter. The filter passes much of the acoustic energy through the walls of the mask or mouthpiece at a location or locations close to the face. The lower frequency airflow components are funneled by the mask or mouthpiece coupling element through an airflow-measurement transducer. The acoustic filtering can be implemented by a membrane, or array of membranes, in the wall of a chamber located close to, or formed as part of, the mask or mouthpiece. An optional inertive-impedance-forming constriction may be placed in the flow pathway between the chamber and the airflow transducer to provide additional acoustic filtering. By making the acoustic filtering process sufficiently thorough, the low-frequency components funneled by the mask or mouthpiece to the transducer contain none of the momentary reversals in flow direction that normally occur during egressive voice production. The mask or mouthpiece coupling element may be used with a transducer that only measures unidirectional flow. Additional acoustic filter elements may be added in the flow path to the transducer and may further reduce the acoustic energy reaching the transducer.