Abstract
Auditory information is processed in a fine-to-crude hierarchical scheme, from low-level acoustic information to high-level abstract representations, such as phonological labels. We now ask whether fine acoustic information, which is not retained at high levels, can still be used to extract speech from noise. Previous theories suggested either full availability of low-level information or availability that is limited by task difficulty. We propose a third alternative, based on the Reverse Hierarchy Theory (RHT), originally derived to describe the relations between the processing hierarchy and visual perception. RHT asserts that only the higher levels of the hierarchy are immediately available for perception. Direct access to low-level information requires specific conditions, and can be achieved only at the cost of concurrent comprehension. We tested the predictions of these three views in a series of experiments in which we measured the benefits from utilizing low-level binaural information for speech perception, and compared it to that predicted from a model of the early auditory system. Only auditory RHT could account for the full pattern of the results, suggesting that similar defaults and tradeoffs underlie the relations between hierarchical processing and perception in the visual and auditory modalities.
Highlights
It is commonly accepted that auditory information is processed along the auditory pathways in a hierarchical manner [1,2,3,4,5,6,7,8], as in other sensory systems [9,10]
The finding that increased difficulty does not decrease the use of low-level information indicates that, in contrast to the limited capacity view, attentional load is not the bottleneck for our ability to use low-level information
We found that when the set of stimuli was composed of phonologically different words, binaural benefits matched those predicted by the ideal listener model under different types of task requirements (Study 1, Experiments I and II), different levels of task difficulty (Study 2), and different binaural protocols (Study 1, Experiments III and IV)
Summary
It is commonly accepted that auditory information is processed along the auditory pathways in a hierarchical manner [1,2,3,4,5,6,7,8], as in other sensory systems [9,10]. Cortical levels integrate across time and frequency, and form more abstract, spectrotemporally broader, categories [5,6,7,8,17,18,19,20,21,22]. One of these higher representation levels is believed to be the phonological representation that underlies human speech perception [23,24,25,26,27,28,29,30,31]. A crucial property of these higher levels is the fact that acoustically different stimuli may belong to the same category (e.g., different instances of /ba/), whereas acoustically more similar stimuli may belong to different categories (e.g., similar instances of /ba/ and /da/) [20]
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.
