The effects of variability on context effects and psychometric function slopes in speaking rate normalizationa)

Area of Science:

• Psycholinguistics
• Auditory Perception
• Speech Processing

Background:

• Acoustic context significantly influences speech perception.
• Previous research showed talker variability, not content variability, reduced spectral contrast effects.
• The impact of contextual variability on temporal contrast effects (TCEs) remained unexplored.

Purpose of the Study:

• To investigate how talker and sentence variability affect temporal contrast effects (TCEs) in speech perception.
• To determine if findings on spectral contrast effects extend to temporal contrast effects.
• To understand the interplay of acoustic, talker, and sentence variability in TCEs.

Main Methods:

• Utilized context sentences and conditions from Assgari and Stilp (2015) with fast and slow speaking rates.
• Manipulated talker variability (one vs. 200 talkers) and sentence variability (one vs. 200 sentences).
• Measured TCE magnitudes and psychometric function slopes under different variability conditions.

Main Results:

• Both sentence variability and talker variability independently diminished TCE magnitudes.
• Talker variability also led to shallower psychometric function slopes.
• Matching speaking rates across conditions did not equalize TCEs or slopes, indicating complexity beyond rate alone.

Conclusions:

• Talker and sentence variability interact with acoustic factors to shape temporal contrast effects.
• These findings highlight the intricate mechanisms underlying speaking rate normalization in speech perception.
• The study underscores the importance of considering multiple sources of variability in understanding auditory perception.