Auditory enhancement and spectral contrast effects in speech perception

Area of Science:

• Auditory perception
• Psychoacoustics
• Speech processing

Background:

• Auditory perception is sensitive to spectral context.
• Auditory enhancement effects (EEs) and spectral contrast effects (SCEs) are distinct perceptual phenomena.
• EEs and SCEs have been suggested to be related but studied separately.

Purpose of the Study:

• To investigate the relationship between EEs and SCEs.
• To demonstrate EEs and SCEs using identical speech materials.
• To determine if EEs and SCEs influence speech categorization similarly.

Main Methods:

• Listeners categorized vowels or consonants after hearing sentences filtered with bandpass or bandstop filters.
• Experiment 1 used bandpass/bandstop filters to elicit SCEs/EEs.
• Experiment 2 used variable-depth notch filters to quantify EE magnitude.

Main Results:

• Bandpass filtering produced SCEs, while bandstop filtering produced EEs.
• The magnitudes of EEs and SCEs were significantly correlated at the individual differences level.
• EE magnitude increased with deeper notches, paralleling SCEs' response to spectral peaks.

Conclusions:

• EEs and SCEs are linked phenomena within auditory perception.
• Both EEs and SCEs systematically shape speech categorization.
• These findings suggest a unified mechanism underlying context-dependent auditory perception.