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Two experiments used subjective and objective measures to study the automaticity and primacy of auditory streaming. Listeners heard sequences of "ABA-" triplets, where "A" and "B" were tones of different frequencies and "-" was a silent gap. Segregation was more frequently reported, and rhythmically deviant triplets less well detected, for a greater between-tone frequency separation and later in the sequence. In Experiment 1, performing a competing auditory task for the first part of the sequence led to a reduction in subsequent streaming compared to when the tones were attended throughout. This is consistent with focused attention promoting streaming, and/or with attention switches resetting it. However, the proportion of segregated reports increased more rapidly following a switch than at the start of a sequence, indicating that some streaming occurred automatically. Modeling ruled out a simple "covert attention" account of this finding. Experiment 2 required listeners to perform subjective and objective tasks concurrently. It revealed superior performance during integrated compared to segregated reports, beyond that explained by the codependence of the two measures on stimulus parameters. We argue that listeners have limited access to low-level stimulus representations once perceptual organization has occurred, and that subjective and objective streaming measures partly index the same processes., ((c) 2016 APA, all rights reserved).)

Biologically salient sounds, including speech, are rarely heard in isolation. Our brains must therefore organize the input arising from multiple sources into separate "streams" and, in the case of speech, map the acoustic components of the target signal onto meaning. These auditory and linguistic processes have traditionally been considered to occur sequentially and are typically studied independently [1, 2]. However, evidence that streaming is modified or reset by attention [3], and that lexical knowledge can affect reports of speech sound identity [4, 5], suggests that higher-level factors may influence perceptual organization. In two experiments, listeners heard sequences of repeated words or acoustically matched nonwords. After several presentations, they reported that the initial /s/ sound in each syllable formed a separate stream; the percept then fluctuated between the streamed and fused states in a bistable manner. In addition to measuring these verbal transformations, we assessed streaming objectively by requiring listeners to detect occasional targets-syllables containing a gap after the initial /s/. Performance was better when streaming caused the syllables preceding the target to transform from words into nonwords, rather than from nonwords into words. Our results show that auditory stream formation is influenced not only by the acoustic properties of speech sounds, but also by higher-level processes involved in recognizing familiar words., (Copyright © 2013 The Authors. Published by Elsevier Inc. All rights reserved.)