Auditory filter asymmetry at 2000 Hz in 80 normal-hearing ears

Abstract

Auditory filter asymmetry, bandwidth, dynamic range, and efficiency was measured at 2000 Hz in both ears of 40 naive, normal-hearing adults, counterbalanced for sex and initial ear tested. The filters were measured with 200-ms tonal signals temporally centered in 300-ms maskers. The maskers were notched noises presented at a spectrum level of 40 dB SPL. Quiet thresholds for the signal were also obtained. The distributions of the measured variables and correlations between them are reported. The average filter was nearly symmetric but the most common filters had steeper upper slopes. The shapes of the two sides of the filter were independent. Filter asymmetry was not correlated with the equivalent rectangular bandwidth (ERB), and quiet threshold was not consistently correlated with the dynamic range of the filter or with ERB. The mean ERB was 255 Hz.

Bark and ERB bilinear transforms

“…A simple, closed-form, invertible expression which comes very close to the optimal Chebyshev allpass coefficient versus sampling rate was given in (26) for the Bark-scale case and in (30) for the ERB-scale case.…”

“…In fact, the optimal warping is within 0.04 Bark of the optimal warping. Since the experimental uncertainty when measuring critical bands is on the order of a tenth of a Bark or more [27]- [30], we consider the optimal Chebyshev and least-squares maps to be equivalent psychoacoustically. …”

“…However, the range of auditory-filter bandwidths measured in 93 young normal subjects at 2 kHz [27] was 230-410 Hz, which is 26% to 32% relative to 310 Hz. In [30], 40 subjects were measured, yielding auditory-filter bandwidths between 33% and 65%, with a standard deviation of 18%. It may thus be concluded that a worst-case mapping error on the order of 20%, while probably detectable by "golden ears" listeners, lies well within the range of experimental deviations in the empirical measurement of auditory bandwidth.…”

“…For an approximation to the optimal Chebyshev ERB frequency mapping, the arctangent formula becomes (30) where is in kHz. This formula is plotted along with the various optimal curves in Fig.…”

Learning problems, delayed development, and puberty

“…We omitted the most deviant of three estimates if the SD was Ͼ15 dB either across three estimates (new data) (10) or across the first two estimates (20). Such deviant thresholds have been obtained, and removed from analyses, in other investigations using the maximum-likelihood method (27)(28)(29). They have been reported to occur with approximately equal frequency (on Ϸ7% of estimates) for listeners with LPs and controls (29) and in approximately equal numbers of 8-year-old, 10-year-old, and adult controls (20).…”