title: Recognition of filtered words in noise at higher-than-normal levels: decreases in scores with and without increases in masking.
abstract: To examine spectral effects on declines in speech recognition in noise at high levels, word recognition for 18 young adults with normal hearing was assessed for low-pass-filtered speech and speech-shaped maskers or high-pass-filtered speech and speech-shaped maskers at three speech levels (70, 77, and 84 dB SPL) for each of three signal-to-noise ratios (+8, +3, and -2 dB). An additional low-level noise produced equivalent masked thresholds for all subjects. Pure-tone thresholds were measured in quiet and in all maskers. If word recognition was determined entirely by signal-to-noise ratio, and was independent of signal levels and the spectral content of speech and maskers, scores should remain constant with increasing level for both low- and high-frequency speech and maskers. Recognition of low-frequency speech in low-frequency maskers and high-frequency speech in high-frequency maskers decreased significantly with increasing speech level when signal-to-noise ratio was held constant. For low-frequency speech and speech-shaped maskers, the decline was attributed to nonlinear growth of masking which reduced the "effective" signal-to-noise ratio at high levels, similar to previous results for broadband speech and speech-shaped maskers. Masking growth and reduced "effective" signal-to-noise ratio accounted for some but not all the decline in recognition of high-frequency speech in high-frequency maskers.
authors.affiliation: Department of Otolaryngology-Head and Neck Surgery, Medical University of South Carolina, 135 Rutledge Avenue, PO. Box 250550, Charleston, South Carolina 29425, USA. dubnojr@musc.edu
authors.forename: Judy R
authors.initials: JR
authors.lastname: Dubno
authors.forename: Amy R
authors.initials: AR
authors.lastname: Horwitz
authors.forename: Jayne B
authors.initials: JB
authors.lastname: Ahlstrom
mesh_terms: D000161:Acoustic Stimulation / Q000295:instrumentation*; D000328:Adult; D000704:Analysis of Variance; D006801:Humans; D009622:Noise / Q000009:adverse effects*; D010470:Perceptual Masking / Q000502:physiology*; D011571:Psychoacoustics; D013061:Speech Acoustics; D013067:Speech Perception / Q000502:physiology*; D013069:Speech Reception Threshold Test