Perceptual attenuation of nonfocused auditory streams

Abstract

The aim of this study was to measure the perceptual attenuation, measured in decibels, resulting from the focusing of attention on one stream within a multistream auditory sequence, The intensity of a nonfocused stream was increased until the accuracy of detecting a temporal irregularity in this stream was the same as in a focused stream, Eight subjects were required to detect a temporal irregularity created by delaying or advancing one tone which could be situated in one of three temporally regular streams played simultaneously to create a multistream sequence. The three streams differed in tempo and frequency. Subjects' attention was focused on one of the streams by preceding the multistream sequence with one of the single streams (a cue). Wefirst established the size of temporal irregularity detected at a 900Allevel in cued streams, confirming that subjects were able to focus on one particular stream, Second, an irregularity of this size was not detected above chance level in noncued streams, demonstrating that listeners focus only on the cued stream, Third, for 5 subjects, a 15-dBincrease in the level of one of the noncued streams was necessary to bring detection up to that found in the cued streams, This gain provides an equivalent measure of the perceptual attenuation of nonfocused streams. For 3 other subjects, detection in the noncued stream remained at chance performance whatever the leveL For all subjects, detection in the cued stream decreased slightly as the level of the noncued stream increased. Weconclude that the attenuation of nonfocused auditory streams can attain as much as 15 dB, at least for some subjects.The auditory system does not passively analyze information as would a machine, decoding every event in the same way irrespective of its importance. Rather, information about events is organized at an early stage in auditory processing, depending on the events' similarity to other sounds, their spatial location, and temporal structure. If several sound events occur over the same time span, then information about frequency, amplitude, and duration of these events is mixed together. A major question in auditory perception research today is how the system is able to segregate information from this mixture to recover the original events. One organizing principle is that ofthe creation ofauditory streams in which sound events with similar physical characteristics (frequency, temporal regularity, tempo, spatial orientation, intensity, timbre, changes in spectral envelope, etc.) are presumed to originate from the same source (Bregman, 1990;McAdams, 1984). Thus,

Auditory stream segregation using bandpass noises: evidence from event-related potentials

“…Research has demonstrated that auditory stream segregation may operate on various physical properties, such as the sound spectrum (Bregman and Campbell, 1971; Warren and Obusek, 1972; van Noorden, 1975; Dannenbring and Bregman, 1976a,b; Bregman et al, 1999) and the temporal envelopes (Singh and Bregman, 1997; Vliegen et al, 1999; Vliegen and Oxenham, 1999; Grimault et al, 2000, 2001, 2002; Roberts et al, 2002). Behavioral (van Noorden, 1975; Botte et al, 1997; Brochard et al, 1999) and neurophysiological (Sussman et al, 1998a, 2005; Sussman and Steinschneider, 2009) studies have further indicated that listeners′ voluntary attention facilitates stream segregation.…”

Change detection in multi-voice music: The role of musical structure, musical training, and task demands.

“…This task analysis is consistent with Sloboda's (1985) proposal that "focal attention" allows for the detection of subtle changes within the focused stream whereas information pickup from the nonfocused streams is weakened. Some support for this conceptualization is provided by a number of studies of selective attention based on frequency (i.e., pitch) for both simple (e.g., Dai, Scharf, & Buus, 1991) and complex (e.g., Botte et al, 1997;Jones et al, 1995) auditory stimuli.…”

“…Conversely, other studies have indicated that the ability to choose to listen either selectively or integratively ("attentional flexibility") may be constrained by primitive processes (Acker & Pastore, 1996b;Botte, Drake, Brochard, & McAdams, 1997;Jones, Jagacinski, Yee, Floyd, & Klapp, 1995). The apparent discrepancy in results is difficult to resolve because these previous studies have used differing stimuli and either have not compared the abilities of musicians and nonmusicians (e.g., Acker & Pastore, 1996a, 1996bPalmer & Holleran, 1994) or have not compared these two groups in tasks that require the detection of changes in musical structure (Jones et al, 1995).…”

The role of attention in the formation of auditory streams

“…Some researchers have argued that attention is crucial even for stream formation that is governed by primitive processes (Alain & Woods, 1997;Botte, Drake, Brochard, & McAdams, 1997;Brochard, Drake, Botte, & McAdams, 1999;Carlyon et al, 2001;M. R. Jones, 1976), whereas other researchers have argued that the primitive stream formation processes can occur outside the focus of attention (Bregman, 1990;Macken, Tremblay, Houghton, Nicholls, & Jones, 2003;Ritter, Sussman, & Molholm, 2000;Sussman, Č eponienė, Shestakova, Näätänen, & Winkler, 2001;Sussman, Ritter, & Vaughan, 1998a.…”