Masker fringe and binaural detection

Abstract

Yost [J. Acoust. Soc. Am. 78,901-907 (1985)] found that the detectability of a 30-ms dichotic signal (S pi) in a 30-ms diotic noise (No) was not affected by the presence of a 500-ms dichotic forward fringe (N pi). Kollmeier and Gilkey [J. Acoust. Soc. Am. 87, 1709-1719, (1990)] performed a somewhat different experiment and varied the onset time of a 25-ms S pi signal in a 750-ms noise that switched, after 375-ms, from N pi to No. In contrast to Yost, they found that the N pi segment of the noise reduced the detectability of the signal even when the signal was temporally delayed well into the No segment of the noise and suggested that the N pi segment of noise acted as a forward masker. To resolve this apparent conflict, the present study investigated the detectability of a brief S pi signal in the presence of an No masker of the same duration as the signal. The masker was preceded by quiet or an N pi forward fringe and followed by quiet, an No, or N pi backward fringe. The present study differs from most previous studies of the effects of the masker fringe in that the onset time of the signal was systematically varied to examine how masking changes during the time course of the complex fringe-masker-fringe stimulus.(ABSTRACT TRUNCATED AT 250 WORDS)

Binaural masking experiments using noise maskers with frequency-dependent interaural phase differences. I: Influence of signal and masker duration

“…The general effects of masker duration and masker fringe on the BMLD are similar for single-interval yes-no procedures (as in McFadden, 1966;Robinson and Trahiotis, 1972;Yost, 1985 ), 2IFC (as in McFadden, 1966;Trahiotis et al, 1972;Gilkey et al, 1990) or 3IFC procedures (Kohlrausch, 1986 and the present study) and Bekesy tracking procedures ).…”

“…This slight increase in BMLD has been observed as well for continuous noise maskers (Blodgett et al, 1958;Green, 1966;Robinson and Trahiotis, 1972;Wilson and Fugleberg, 1987) as for pulsed maskers (Kohlrausch, 1986), where changes in signal duration also vary the time interval between masker onset and signal onset (forward fringe). On the contrary, shortening the masker duration has a more substantial influence and leads to much smaller BMLD values (McFadden, 1966;Robinson and Trahiotis, 1972;Trahiotis et al, 1972;Yost, 1985;Kohlrausch, 1986;Gilkey et al, 1990). The strongest decrease in BMLD is observed, if a short masker is gated simultaneously with a short signal (Robinson and Trahiotis, 1972).…”

“…In this case, the total duration of the masker is shortened and the forward fringe is reduced to zero. Although for simultaneous presentation of signal and masker, these two parameters are interdependent (e.g., a change in masker duration cannot be realized without changes in either forward or backward fringe or both), their influence on binaural unmasking may be partly separated by combining the findings of different studies as follows: For a given temporal position of the signal within the masker, e.g., at the masker onset (no forward fringe), a shorter masker leads to smaller BMLDs Gilkey et al, 1990); for a given duration of the masker, the BMLD is highest if the masker is presented as well with a forward as with a backward fringe and lowest for signal position at masker onset (Gilkey et al, 1990). The interaural parameters of the maskers have an additional effect on the change of BMLD for shorter maskers.…”

Interaural fluctuations and the detection of interaural incoherence. II. Brief duration noises

“…The variation leads to improved detection. A similar observation was made by Gilkey et al ͑1990͒, who referred to the sudden change in interaural parameters as an "onset-effect." By contrast, when the signal duration is long, the interaural fluctuations introduced by the out-ofphase signal produce temporal variations of their own, and a fringe becomes less valuable.…”

The Impact of Masker Fringe and Masker Sparial Uncertainty on Sound Localization

“…It has been argued that this masker fringe provides a baseline set of stimulus parameters against which the signal may be more easily detected [3,4]. A slightly different, but related, explanation would suggest that the fringe provides the listener with information about the parameters of the masker occurring during the signal interval -that is, the fringe reduces masker uncertainty.…”