Estimates of compression at low and high frequencies using masking additivity in normal and impaired ears

• Published in: The Journal of the Acoustical Society of America Vol. 123; no. 6; pp. 4321 - 4330
• Main Authors: Plack, Christopher J., Oxenham, Andrew J., Simonson, Andrea M., O'Hanlon, Catherine G., Drga, Vit, Arifianto, Dhany
• Format: Journal Article
• Language: English
• Published: Woodbury, NY Acoustical Society of America 01.06.2008; American Institute of Physics
• Subjects: Acoustic Stimulation; Adult; Audition; Auditory Perception - physiology; Auditory Threshold - physiology; Basilar Membrane - physiology; Biological and medical sciences; Fundamental and applied biological sciences. Psychology; Hearing - physiology; Hearing Disorders - physiopathology; Humans; Perception; Perceptual Masking; Physiological Acoustics; Psychology. Psychoanalysis. Psychiatry; Psychology. Psychophysiology; Reference Values; Sound Spectrography; Auditory disorder; Hearing; Masking; Healthy subject; High frequency; Low frequency
• ISSN: 0001-4966; 1520-8524; 1520-8524
• DOI: 10.1121/1.2908297

Auditory compression was estimated at 250 and 4000 Hz by using the additivity of forward masking technique, which measures the effects on signal threshold of combining two temporally nonoverlapping forward maskers. The increase in threshold in the combined-masker condition compared to the individual-masker conditions can be used to estimate compression. The signal was a 250 or 4000 Hz tone burst and the maskers (M1 and M2) were bands of noise. Signal thresholds were measured in the presence of M1 and M2 alone and combined for a range of masker levels. The results were used to derive response functions at each frequency. The procedure was conducted with normal-hearing and hearing-impaired listeners. The results suggest that the response function in normal ears is similar at 250 and 4000 Hz with a mid level compression exponent of about 0.2. However, compression extends over a smaller range of levels at 250 Hz . The results confirm previous estimates of compression using temporal masking curves (TMCs) without assuming a linear off-frequency reference as in the TMC procedure. The impaired ears generally showed less compression. Importantly, some impaired ears showed a linear response at 250 Hz , providing a further indication that low-frequency compression originates in the cochlea.