title: Spectrotemporal modulation sensitivity for hearing-impaired listeners: dependence on carrier center frequency and the relationship to speech intelligibility.
abstract: Poor speech understanding in noise by hearing-impaired (HI) listeners is only partly explained by elevated audiometric thresholds. Suprathreshold-processing impairments such as reduced temporal or spectral resolution or temporal fine-structure (TFS) processing ability might also contribute. Although speech contains dynamic combinations of temporal and spectral modulation and TFS content, these capabilities are often treated separately. Modulation-depth detection thresholds for spectrotemporal modulation (STM) applied to octave-band noise were measured for normal-hearing and HI listeners as a function of temporal modulation rate (4-32 Hz), spectral ripple density [0.5-4 cycles/octave (c/o)] and carrier center frequency (500-4000 Hz). STM sensitivity was worse than normal for HI listeners only for a low-frequency carrier (1000 Hz) at low temporal modulation rates (4-12 Hz) and a spectral ripple density of 2 c/o, and for a high-frequency carrier (4000 Hz) at a high spectral ripple density (4 c/o). STM sensitivity for the 4-Hz, 4-c/o condition for a 4000-Hz carrier and for the 4-Hz, 2-c/o condition for a 1000-Hz carrier were correlated with speech-recognition performance in noise after partialling out the audiogram-based speech-intelligibility index. Poor speech-reception and STM-detection performance for HI listeners may be related to a combination of reduced frequency selectivity and a TFS-processing deficit limiting the ability to track spectral-peak movements.
authors.affiliation: Program in Speech and Hearing Bioscience and Technology, Harvard University-Massachusetts Institute of Technology, Cambridge, Massachusetts 02139.
authors.forename: Golbarg
authors.initials: G
authors.lastname: Mehraei
authors.affiliation: VA RR&D National Center for Rehabilitative Auditory Research, Portland VA Medical Center, Portland, Oregon 97239.
authors.forename: Frederick J
authors.initials: FJ
authors.lastname: Gallun
authors.affiliation: VA RR&D National Center for Rehabilitative Auditory Research, Portland VA Medical Center, Portland, Oregon 97239.
authors.forename: Marjorie R
authors.initials: MR
authors.lastname: Leek
authors.affiliation: National Military Audiology and Speech Pathology Center, Walter Reed National Military Medical Center, Bethesda, Maryland 20889.
authors.forename: Joshua G W
authors.initials: JG
authors.lastname: Bernstein
mesh_terms: D000161:Acoustic Stimulation; D000328:Adult; D001299:Audiometry; D001309:Auditory Threshold; D032882:Comprehension; D003463:Cues; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009622:Noise / Q000009:adverse effects*; D010470:Perceptual Masking; D019986:Persons with Hearing Disabilities / Q000523:psychology*; D011571:Psychoacoustics; D013018:Sound Spectrography; D013065:Speech Intelligibility; D013067:Speech Perception; D013997:Time Factors; D055815:Young Adult