Abstract
Purpose:
This study examined the impact of clear speech on perceived naturalness. We compared habitual speech (HS), untrained clear speech (UCS), and clear speech after a brief training (trained clear speech [TCS]) and examined whether acoustic variables differed between conditions and predicted naturalness.
Method:
Twelve adult female talkers read sentences in three conditions (HS, UCS, TCS). Twenty-eight normal-hearing adults rated naturalness on a 1–9 scale. Along with naturalness, acoustic measures of speech rate, number of pauses, and pause duration were obtained and compared between speaking conditions via linear mixed-effects models (LMMs).
Results:
LMMs showed a significant effect of speaking condition on the four dependent variables (
p
Conclusions:
A 30-min clear speech training reduced speech naturalness compared to HS and UCS. A slower speech rate and increased pausing were associated with inferior naturalness ratings, although these features may not fully explain the reduced naturalness of TCS. The findings highlight an intelligibility–naturalness trade-off: Strategies that improve clarity can make speech sound less natural. Clinical protocols may benefit from promoting clarity-enhancing techniques that avoid excessive slowing or disruption of prosody and/or from providing real-time naturalness and intelligibility ratings as feedback during training.