Frequency selectivity as a function of level and frequency measured with uniformly exciting notched noise

Abstract

Thresholds for detecting sinusoidal signals were measured as a function of the spectral width of a notch in a noise masker. The notch was positioned both symmetrically and asymmetrically around the signal frequency. The noise was designed to create equal excitation per ERB within its passbands (uniformly exciting noise), after allowing for the transfer function of the headphone and the middle ear. For a signal frequency of 250 Hz, the level per ERB ranged from 35 to 80 dB in 15-dB steps. For signal frequencies of 500, 1,000, 2,000, and 4,000 Hz, the level per ERB ranged from 40 to 70 dB per ERB in 15-dB steps. Auditory filter shapes were derived from the data by modeling the auditory filter as the sum of a sharply tuned tip filter and a broader tail filter. The gain of the tip filter was assumed to be a function of level. The shape of the tip filter and the gain and shape of the tail filter were assumed to be level independent. The data for all levels were fitted simultaneously. The data were fitted best when the gain of the tip filter was assumed to be a function of the signal level (as opposed to the masker level per ERB). The filter shapes showed a level dependence that qualitatively resembled the level dependence of filtering on the basilar membrane. The maximum gain of the tip filter tended to increase with increasing center frequency up to 1 kHz, but to remain roughly constant for higher frequencies.

Level-dependent changes in detection of temporal gaps in noise markers by adults with normal and impaired hearing

“…The authors suggested that the "recruitment-like effect" occurring in masked normal hearing listeners may be functionally dissimilar to the loudness recruitment associated with cochlear hearing loss. However, given the signal presentation levels, results in Hall and Gross (1997) may be consistent with models of cochlear nonlinearities (see, e.g., Glasberg and Moore, 2000). These models assume more linear responses at lower and higher levels and the strongest compression at mid levels, $50 dB SPL.…”

Physiology, Psychoacoustics and Cognition in Normal and Impaired Hearing

“…It is well known that frequency selectivity becomes poorer in NH listeners at high levels (e.g., Nelson and Freyman 1984;Glasberg and Moore 2000). Apparently the filter broadening with level in NH listeners is sufficient to reduce the effects of inherent masker fluctuations.…”

Effects of presentation level on the identification of speech with altered short-term spectra

“…The level effects of FSS could be inferred from the increasing bandwidth with noise level, which was revealed by the human psychoacoustical results of tone detection in notched-noise masking [14]. Several studies showed that the bandwidth tends to expand as the masker level and tone frequency increase [15]; bandwidth especially expands toward the lower frequency regions from the tone frequency [16][17][18]. The level-dependent intelligibility of FSS-16 ms may similarly reflect the expanded bandwidths to lower frequency regions in response to the amplitude spectra at high-frequency regions.…”