Effects of spectral modulation filtering on vowel identification.
The goal of this study was to measure the effects of global spectral manipulations on vowel identification by progressively high-pass filtering vowel stimuli in the spectral modulation domain. Twelve American-English vowels, naturally spoken by a female talker, were subjected to varied degrees of high-pass filtering in the spectral modulation domain, with cutoff frequencies of 0.0, 0.5, 1.0, 1.5, and 2.0 cycles/octave. Identification performance for vowels presented at 70 dB sound pressure level with and without spectral modulation filtering was measured for five normal-hearing listeners. Results indicated that vowel identification performance was progressively degraded as the spectral modulation cutoff frequency increased. Degradation of vowel identification was greater for back vowels than for front or central vowels. Detailed acoustic analyses indicated that spectral modulation filtering resulted in a more crowded vowel space (F1xF2), reduced spectral contrast, and reduced spectral tilt relative to the original unfiltered vowels. Changes in the global spectral features produced by spectral modulation filtering were associated with substantial reduction in vowel identification. The results indicated that the spectral cues critical for vowel identification were represented by spectral modulation frequencies below 2 cycles/octave. These results are considered in terms of the interactions among spectral shape perception, spectral smearing, and speech perception.
Liu
Chang
C
Department of Communication Sciences and Disorders, University of Texas at Austin, 1 University Station A1100, Austin, Texas 78712, USA. changliu@mail.utexas.edu
Eddins
David A
DA
D000161:Acoustic Stimulation; D000328:Adult; D001301:Audiometry, Pure-Tone; D001302:Audiometry, Speech; D001309:Auditory Threshold; D003463:Cues; D005260:Female; D006801:Humans; D010470:Perceptual Masking; D011571:Psychoacoustics; D017603:Signal Detection, Psychological; D013018:Sound Spectrography; D013061:Speech Acoustics; D013065:Speech Intelligibility; D013067:Speech Perception; D013997:Time Factors; D055815:Young Adult