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The deterioration of hearing with age: Frequency selectivity, the critical ratio, the audiogram, and speech threshold
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1982
Year
PsychoacousticsEngineeringAuditory Filter ShapesFrequency SelectivityNoiseCritical RatioAuditory ScienceStatisticsHealth SciencesAuditory ProcessingAuditory ModelingAudiologyHuman HearingGeriatric AudiologyHearing LossAuditory PhysiologySpeech ProcessingSpeech ThresholdSpeech PerceptionAuditory System
The study develops an alternative, one‑point measure of frequency selectivity that is both sensitive and reliable, using a filter‑shape model of masking. Frequency selectivity was assessed by masking sinusoidal or filtered‑speech signals with wideband noise containing a notch centered on the signal, and a sensitive one‑point measure was derived via a filter‑shape model of masking. Widening the notch improved performance for both signal types, yet the rate of improvement decreased with age, revealing progressive loss of frequency selectivity; filter‑shape analysis showed passband broadening and dynamic‑range loss accelerating after age 55, while speech experiments exhibited smaller effects, and the critical ratio was found to be a poor estimator of selectivity.
The frequency selectivity of the auditory system was measured by masking a sinusoidal signal (0.5, 2.0, or 4.0 kHz) or a filtered-speech signal with a wideband noise having a notch, or stopband, centered on the signal. As the notch was widened performance improved for both types of signal but the rate of improvement decreased as the age of the 16 listeners increased from 23 to 75 years, indicating a loss in frequency selectivity with age. Auditory filter shapes derived from the tone-in-noise data show (a) that the passband of the filter broadens progressively with age, and (b) that the dynamic range of the filter ages like the audiogram. That is, the range changes little with age before 55, but beyond this point there is an accelerating rate of loss. The speech experiment shows comparable but smaller effects. The filter-width measurements show that the critical ratio is a poor estimator of frequency selectivity because it confounds the tuning of the system with the efficiency of the signal-detection and speech-processing mechanisms that follow the filter. An alternative, one-point measure of frequency selectivity, which is both sensitive and reliable, is developed via the filter-shape model of masking.