Vocal register "shift" identification in a modified breathing atmosphere.
An attempt was made to determine whether listeners' perception of vocal register "shift" was related to speaker fundamental frequency or to supralaryngeal resonance. The method was to have speakers phonate tones while breathing air and, alternatively, a helium--oxygen mixture which influences resonance but not fundamental frequency. Recordings were made of these phonations and played to judges who were required to identify between which tones the register shift occurred. Results showed that judges had more difficulty identifying the shift point when speakers were phonating in air than with the HeO2 mixture. Comparison also was made between the speaker's self-judgment of shift and that of listeners. Under the helium condition the speakers and listeners were in nearly complete agreement, with the greatest variability occurring between the groups for the air breathing condition. These results indicate that register change is related to modification of laryngeal function.