Articulatory rate and perceptual constancy in phonetic perception

Area of Science:

• Phonetics and Speech Science
• Auditory Perception
• Speech Production

Background:

• Perception of stop consonants (e.g., /b/, /d/, /g/ vs. /p/, /t/, /k/) is crucial for understanding spoken language.
• Previous research suggests external factors can influence phonetic perception, but the precise mechanisms remain debated.

Purpose of the Study:

• To investigate the role of articulatory rate in the perception of syllable-initial voiced versus voiceless stop consonants.
• To determine whether perceived consonant voicing is influenced by extrinsic timing cues or intrinsic properties of speech articulation.

Main Methods:

• Participants listened to speech stimuli where the rate of articulation was systematically varied.
• Experiments manipulated the duration of precursor syllables, silent stop closure, and test syllables.
• A control condition involved varying the tempo of a non-speech melody to assess its impact on consonant perception.

Main Results:

• Reducing the articulatory rate of preceding speech significantly increased the perception of voiced consonants.
• The duration of the preceding syllable, silent closure, and the test syllable itself were key factors influencing voicing perception.
• Altering the tempo of a non-speech melody had no effect on the perception of embedded consonants.

Conclusions:

• The perception of consonant voicing is primarily influenced by intrinsic timing within the speech articulation itself, not by extrinsic perceptual timing mechanisms.
• Temporal characteristics of the constriction, occlusion, and release phases of articulation are critical for voicing perception.
• Findings support models of speech production where timing is intrinsic to phonetic events.