Abstract
The purpose of this study was to investigate the roles of spectral overlap and amplitude modulation (AM) rate for stream segregation for noise signals, as well as to test the build-up effect based on these two cues. Segregation ability was evaluated using an objective paradigm with listeners' attention focused on stream segregation. Stimulus sequences consisted of two interleaved sets of bandpass noise bursts (A and B bursts). The A and B bursts differed in spectrum, AM-rate, or both. The amount of the difference between the two sets of noise bursts was varied. Long and short sequences were studied to investigate the build-up effect for segregation based on spectral and AM-rate differences. Results showed the following: (1). Stream segregation ability increased with greater spectral separation. (2). Larger AM-rate separations were associated with stronger segregation abilities. (3). Spectral separation was found to elicit the build-up effect for the range of spectral differences assessed in the current study. (4). AM-rate separation interacted with spectral separation suggesting an additive effect of spectral separation and AM-rate separation on segregation build-up. The findings suggest that, when normal-hearing listeners direct their attention towards segregation, they are able to segregate auditory streams based on reduced spectral contrast cues that vary by the amount of spectral overlap. Further, regardless of the spectral separation they are able to use AM-rate difference as a secondary/weaker cue. Based on the spectral differences, listeners can segregate auditory streams better as the listening duration is prolonged—i.e., sparse spectral cues elicit build-up segregation; however, AM-rate differences only appear to elicit build-up when in combination with spectral difference cues.
Highlights
IntroductionAuditory stream segregation ( referred to as auditory streaming) occurs naturally in daily life, such as when listening to a talker at a party or when following a melody played by an instrument in an orchestra
Auditory stream segregation occurs naturally in daily life, such as when listening to a talker at a party or when following a melody played by an instrument in an orchestra
The spectral separation and amplitude modulation (AM)-rate separation were assessed for the fixed repeated effect, while the subject variables in the model included participants and the repetitions of d′ measures within each observational unit
Summary
Auditory stream segregation ( referred to as auditory streaming) occurs naturally in daily life, such as when listening to a talker at a party or when following a melody played by an instrument in an orchestra. Listeners with normal hearing (NH) interpret a mixture of ongoing sounds in such a way that sounds from different sources are allocated to individual sound generators that are perceptually concurrent. Both spectral and temporal differences have been documented as cues that can elicit stream segregation in NH listeners. Other research has documented that differences in temporal envelopes (Singh and Bregman, 1997; Vliegen et al, 1999; Vliegen and Oxenham, 1999; Grimault et al, 2000, 2001; Roberts et al, 2002) and amplitude modulation rate (Grimault et al, 2002) can induce stream segregation without the presence of spectral cues
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