Hearing Sensitivity to Shifts of Rippled-Spectrum Sound Signals in Masking Noise

Abstract

The goal of the study was to enlarge knowledge of discrimination of complex sound signals by the auditory system in masking noise. For that, influence of masking noise on detection of shift of rippled spectrum was studied in normal listeners. The signal was a shift of ripple phase within a 0.5-oct wide rippled spectrum centered at 2 kHz. The ripples were frequency-proportional (throughout the band, ripple spacing was a constant proportion of the ripple center frequency). Simultaneous masker was a 0.5-oct noise below-, on-, or above the signal band. Both the low-frequency (center frequency 1 kHz) and on-frequency (the same center frequency as for the signal) maskers increased the thresholds for detecting ripple phase shift. However, the threshold dependence on the masker level was different for these two maskers. For the on-frequency masker, the masking effect primarily depended on the masker/signal ratio: the threshold steeply increased at a ratio of 5 dB, and no shift was detectable at a ratio of 10 dB. For the low-frequency masker, the masking effect primarily depended on the masker level: the threshold increased at a masker level of 80 dB SPL, and no shift was detectable at a masker level of 90 dB (for a signal level of 50 dB) or 100 dB (for a signal level of 80 dB). The high-frequency masker had little effect. The data were successfully simulated using an excitation-pattern model. In this model, the effect of the on-frequency masker appeared to be primarily due to a decrease of ripple depth. The effect of the low-frequency masker appeared due to widening of the auditory filters at high sound levels.

Discrimination of rippled-spectrum patterns in noise: A manifestation of compressive nonlinearity

“…It has been previously noted [35–37] that the growth of masking of the rippled-spectrum discrimination is different for on- and low-frequency maskers. The data presented herein specify this observation.…”

“…In several studies [29, 30, 33], a ripple phase-reversal test was exploited to find the highest resolvable ripple density. In other studies [34, 35], a ripple phase shift was exploited to find the ripple-shift threshold. Contrary to masking-based methods, these tests directly indicate whether the fine spectrum pattern of the rippled-spectrum stimulus is or is not discriminated.…”

“…Using this method, the rippled-spectrum resolution was investigated in background noise. Those studies demonstrated that noise maskers impaired the spectrum-pattern resolution in terms of the ripple density [36–38] and ripple shift [35] when the masker band coincided with the rippled-spectrum signal (on-frequency maskers) or when it was lower in frequency than the signal (low-frequency maskers).…”

Rippled spectrum discrimination in noise: Effects of compression

“…The resolution of rippled spectra in normal listeners was investigated in several previous studies (Supin et al, 1994(Supin et al, , 1998(Supin et al, , 1999Nechaev and Supin, 2013;Aronoff and Landsberger, 2013). It has been demonstrated that both on-and low-frequency maskers deteriorate the resolution of the second rippledspectrum structure (Supin et al, 2001(Supin et al, , 2003Nechaev et al, 2015). Based on these data, we supposed that data O. N. Milekhina et al Rippled spectrum discrimination…”

High Ripple-Density Resolution for Discriminating Between Rippled and Nonrippled Signals: Effect of Temporal Processing or Combination Products?

“…Such a masker may produce low-frequency masking of the primary signal (the effect of upward spread of masking). Due to the upward spread of masking, low-frequency maskers reduce the ripple-density resolution ( Milekhina et al., 2017 ; Nechaev et al., 2015 ; Supin et al., 2001 , 2003 ). The low-frequency masking of the primary signal must be distinguished from the on-frequency masking of low-frequency combination products.…”