Abstract
In a complex acoustical environment, the auditory system decides which stimulus components originate from the same source by forming auditory streams, where temporally non-overlapping stimulus portions are considered to originate from one source if their stimulus characteristics are similar. The mechanisms underlying streaming are commonly studied by alternating sequences of A and B signals which are often tones with different frequencies. For similar frequencies, they are grouped into one stream. Otherwise, they are considered to belong to different streams. The present study investigates streaming in cochlear implant (CI) users, where hearing is restored by electrical stimulation of the auditory nerve. CI users listened to 30-s long sequences of alternating A and B harmonic complexes at four different fundamental frequency separations, ranging from 2 to 14 semitones. They had to indicate as promptly as possible after sequence onset, if they perceived one stream or two streams and, in addition, any changes of the percept throughout the rest of the sequence. The conventional view is that the initial percept is always that of a single stream which may after some time change to a percept of two streams. This general build-up hypothesis has recently been challenged on the basis of a new analysis of data of normal-hearing listeners. Using the same experimental paradigm and analysis, the present study found that the results of CI users agree with those of the normal-hearing listeners: (i) the probability of the first decision to be a one-stream percept decreased and that of a two-stream percept increased as Δf increased, and (ii) a build-up was only found for 6 semitones. Only the time elapsed before the listeners made their first decision of the percept was prolonged as compared to normal-hearing listeners. The similarity in the data of the CI user and the normal-hearing listeners indicates that the quality of stream formation is similar in these groups of listeners.
Highlights
Making sense of the complex auditory environment is of eminent importance in life
Since fundamental frequency is the sound feature most often used to study the formation of streams, in the following, stream formation is discussed in relation to this feature only
One aim of this study is to investigate if this restriction results in a different stream formation in cochlear implant (CI) users compared to normal-hearing listeners
Summary
Making sense of the complex auditory environment is of eminent importance in life. For hearing-impaired listeners and for those with their hearing restored by a cochlear implant (CI), a task such as the focusing on a conversational partner in a noisy environment often poses serious problems. Since the pioneering work of Miller and Heise (1950), Bregman and Campbell (1971), and van Noorden (1975), laboratory experiments have used the auditory streaming paradigm to understand the processes that help to disentangle several sound sources. In this paradigm, tones from two sets A and B differing in a specific sound feature are presented in rapid alternation, and listeners are asked if they hear one stream or two co-existing streams. Whereas for large frequency separations, the segregated percept predominates, at intermediate frequency separations the perceptual organization is ambiguous, that is, both integration into one stream and segregation into two streams are possible (see Bregman, 1990, for a review)
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
