Ripple depth and density resolution of rippled noise

Abstract

Depth resolution of spectral ripples was measured in normal humans using a phase-reversal test. The principle of the test was to find the lowest ripple depth at which an interchange of peak and trough position (the phase reversal) in the rippled spectrum is detectable. Using this test, ripple-depth thresholds were measured as a function of ripple density of octave-band rippled noise at center frequencies from 0.5 to 8 kHz. The ripple-depth threshold in the power domain was around 0.2 at low ripple densities of 4-5 relative units (center-frequency-to-ripple-spacing ratio) or 3-3.5 ripples/oct. The threshold increased with the ripple density increase. It reached the highest possible level of 1.0 at ripple density from 7.5 relative units at 0.5 kHz center frequency to 14.3 relative units at 8 kHz (5.2 to 10.0 ripple/oct, respectively). The interrelation between the ripple depth threshold and ripple density can be satisfactorily described by transfer of the signal by frequency-tuned auditory filters.

A cocktail party with a cortical twist: How cortical mechanisms contribute to sound segregation

“…It is implemented by an instantaneous affine wavelet transformation of the spectral slices of the auditory spectrogram. All parameters of these processes are consistent with physiological data in animals ͑Langner, 1992; Miller et al, 2002;Schreiner and Urbas, 1988͒ and psychoacoustical data in human subjects ͑Eddins and Bero, 2007; Green, 1986;Supin et al, 1999;Viemeister, 1979͒. In the current implementation of the model, we have left out several acoustic features that are known to aid stream segregation such as fast AM and FM modulations as well as spatial cues.…”

Evidence of across-channel processing for spectral-ripple discrimination in cochlear implant listeners

“…Spectral-ripple discrimination, originally developed to investigate the spectral resolution of the normal auditory system (e.g., Supin et al, 1994Supin et al, , 1998Supin et al, , 1999, has recently gained a wide range of attention in the cochlear implant (CI) research field (e.g., Henry and Turner, 2003;Henry et al, 2005;Won et al, 2007;Litvak et al, 2007;Saoji et al, 2009;Drennan et al, 2010;Won et al, 2010Won et al, , 2011Anderson et al, 2011). These previous studies demonstrated that spectral-ripple discrimination correlates with vowel and consonant recognition in quiet (Henry et al, 2003(Henry et al, , 2005Saoji et al, 2009), speech perception in noise (Won et al, 2007), and music perception .…”

Relationship between channel interaction and spectral-ripple discrimination in cochlear implant users

“…Performance in the task is correlated with vowel and consonant recognition by CI users in quiet (Henry and Turner, 2003;Henry et al, 2005), speech perception in noise (Won et al, 2007), and music perception . These results have been interpreted as indicating the usefulness of spectral-ripple discrimination thresholds as an approximate metric of the spectral resolution of CI users, much as the ripple phase-inversion technique has been used to characterize the frequency resolving power of listeners with normal hearing (Supin et al, 1994(Supin et al, , 1997(Supin et al, , 1999.…”

“…Higher thresholds (more ripples/octave) indicate better performance. Tests of discrimination or detection of spectrally modulated noise were first used to test listeners with normal hearing (Summers and Leek, 1994;Supin et al, 1994Supin et al, , 1999Macpherson and Middlebrooks, 2003) and were adapted for tests in CI users (Henry and Turner, 2003;Henry et al, 2005, Litvak et al, 2007Won et al, 2007;Saoji et al, 2009). Possible factors that could influence spectralripple discrimination performance in CI listeners include the number of electrodes available to the subjects, amount of intracochlear current spread, integrity or health of the auditory nerve, or sound processing strategies.…”