Upward shifts in the masking pattern with increasing masker intensity

Abstract

Masking patterns obtained with forward-masking paradigms and relatively intense maskers sometimes have their peaks at the masker frequency and sometimes at a frequency well above it. Here it is shown that which outcome is obtained depends upon certain temporal parameters of the procedure. Specifically, the masking pattern for a 2000-Hz tone showed a gradual shift toward higher frequencies as masker intensity was increased from 65 to 95 dB SPL when long signals (about 50 ms) and long masker-to-signal intervals (about 50 ms) were used, but the effect was absent or smaller when the signals and intervals were short. This shift did not occur with a 750-Hz masker. Upward shifts in the masking pattern with increasing masker intensity are in accord with the view that the peak of displacement of the traveling-wave envelope migrates basally with increasing intensity--an idea that has frequently been suggested as an explanation of the so-called half-octave shift so routinely seen in auditory fatigue experiments.

The effects of a high-frequency suppressor on tuning curves and derived basilar-membrane response functions

“…1͒ is in agreement with earlier psychophysical data which show that high-frequency slopes tend to be steeper than lowfrequency slopes ͑Vogten, 1974͑Vogten, , 1978Small and Busse, 1980;Kidd and Feth, 1981;O'Loughlin and Moore, 1981b;Moore and Glasberg, 1982;McFadden and Yama, 1983;Nelson and Freyman, 1984;Jesteadt and Norton, 1985;Nelson, 1991͒. In general, the Q 10 estimates of the PTCs decrease as the masker-signal gap increases, consistent with a broadening of the auditory filter with an increase in level ͑Moore and Nelson and Freyman, 1984͒. The BF of the PTCs shifts to a lower frequency at high masker levels ͑cor-responding to longer masker-signal gaps͒.…”

Underwater temporary threshold shift in pinnipeds: Effects of noise level and duration

“…Consistent with observations of this effect, Schlundt et al ͑2000͒, using brief tones as fatiguing stimuli, found that threshold shifts measured in odontocetes ͑bottlenose dolphins and beluga whales͒ generally occurred at frequencies above the exposure frequency. This type of upward spread in affected frequency has been attributed to the basalward spread in the peak of the cochlear traveling wave under the influence of an increasingly intense sinusoid, and partially attributed to cochlear amplification ͑McFadden and Yama, 1983;McFadden, 1986;Moore et al, 2002͒. Although Nachtigall et al ͑2004͒ recently found maximal threshold shifts approximately one-half octave above the upper limit of a 7-kHz-wide noise band in bottlenose dolphins, this finding has not been shown by some other studies using bands of noise ͑e.g., Neilsen et al, 1986͒. It is possible that exposure to bands of noise does not result in a shift in the peak of the cochlear partition response because of phase differences between individual frequency components, explaining why some experiments fail to demonstrate this effect.…”

Age-related changes in within- and between-channel gap detection using sinusoidal stimuli

“…If the first marker is a 2-kHz tone, the listener is presented with a strong 2-kHz tone followed by the weaker, 2-kHz, aural harmonic generated by the lagging 1-kHz tone. It has long been known that the presence of an intense masker elevates the threshold for a same-frequency probe stimulus following the masker ͑e.g., Duifhuis, 1973;McFadden and Yama, 1983;Nizami, 2003͒. Hence, in the ascending frequency case, the 2-kHz tone is present as a weak-intensity aural harmonic in the leading marker and a 2-kHz tone in the lagging marker.…”