The Effects of Vocal Effort on Bilabial Contact Pressure and Intraoral Air Pressure, and Their Durations

Background: Following surgical removal of the larynx, patients choose an alternate speech-production mechanism. One substitute sound source option is an electrolarynx. However, removal of the larynx alters speech production. The lung-driven, pressurized airstream used to articulate speech is not available. Increasing global effort and exaggerating speech movements have been suggested, but the relationship between an individual’s “effort level” and aerodynamic and kinematic correlates of exaggerated speech movements is not understood. Purpose: This study compared effects of varying speaking effort when using laryngeal speech on speech aerodynamics and kinematics to the same parameters exhibited during electrolaryngeal speech. Methods: Participants produced three bilabial consonants using conversational, clear, and electrolarynx speech modes. Bilabial contact pressure (BCP) peaks, intraoral air pressure (IOAP) peaks, and their durations were measured. Results: BCPs and BCP durations increased from conversational to clear to electrolaryngeal speech, for all phonemes studied. IOAP did not differ significantly as a function of speech mode, while IOAP duration was significantly lengthened during electrolarynx speech. Conclusions: Speech produced with an electrolarynx is different from laryngeal speech and appears associated with greater effort than conversational or clear speech. These results can be generalized to clinical instruction for electrolaryngeal speakers to produce more intelligible speech.