The Effect of Increased Sound Pressure Level on Acoustics and Articulatory Kinematics
J Huber, B Chandrasekaran, J Wolstencroft
Increased mouth opening is associated with increased sound pressure level (SPL), but it is not clear why. It may maintain the distance between fundamental frequency (F0) and first formant frequency (F1). However, it has not been established that an increase in F1 occurs with an increase in mouth opening. Further, it is not clear whether this association exists no matter how an individual is cued to increase SPL. Thirty young adults produced “Buy Bobby a puppy” at comfortable pitch and loudness and in three high SPL conditions (10 dB above comfortable (TEN), twice as loud as comfortable (TAL), and in noise (NOI)). F0 and F1 increased in all high SPL conditions. As SPL increased, mouth opening and F1 increased. The jaw appeared to be the prime mover in the mouth opening mechanism. Overall this effect was robust to differences in cueing. However, the TAL and NOI conditions resulted in a significant lowering of the jaw, whereas the TEN condition did not, suggesting the type of cue may affect the mechanisms used to achieve increased SPL. The TAL and NOI condition may have been more natural cues to increase SPL, allowing subjects to respond in a more habitual manner.