Interrupted-speech perception: Top-down restoration in cochlear implant users

Pranesh Bhargava

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    In difficult listening situations, e.g. in a cocktail party scenario, speech signal that a listener is interested in decoding is often masked by unwanted noise, disrupting bottom-up signalling. A normal hearing (NH) listener is able to withstand a reasonable amount of such disruption and can still achieve good speech perception. This is possible partially because the information encoded in human speech is redundant at various levels like phonetic, morphemic, sentential, discourse, etc. In addition, NH listeners employ various cognitive mechanisms to reconstruct the lost information from disrupted speech signal. Some of these mechanisms are: application of the knowledge of the speaker’s language and its grammatical conventions, expectation formulated on the basis of the information collected previously in the discourse, tracking the auditory information within the speech stream, etc. As a result, (i) some loss of information can be tolerated without loss of meaning, and (ii) some information can be reconstructed on the basis of the leftover information.

    A cochlear implant (CI) is an implantable electronic device that partially reconstructs hearing for individuals with profound or total sensorineural hearing loss. CI users have greater difficulty in understanding speech than NH listeners in challenging listening scenarios where target speech signals are disrupted, e.g. with multiple individuals talking simultaneously or in noisy surroundings.

    This thesis explores if various factors inherent to the signal, and deficits of hearing impairment and/or characteristic of CI signal transmission may be at least partially responsible for the CI users having reduced ability of understanding speech in difficult listening scenarios. I conclude in the thesis that CI users can effectively use top-down restoration mechanisms but the nature and/or extent of the working of these mechanisms may be different in CI users than in NH listeners due to certain factors that may themselves vary among the CI users.
    Originele taal-2English
    KwalificatieDoctor of Philosophy
    Toekennende instantie
    • Rijksuniversiteit Groningen
    Begeleider(s)/adviseur
    • Baskent, Deniz, Supervisor
    • Gaudrain, Etienne, Co-supervisor
    • van Wieringen, A. , Beoordelingscommissie, Externe Persoon
    • Snik, A.F.M., Beoordelingscommissie, Externe Persoon
    • Redeker, Gisela, Beoordelingscommissie
    Datum van toekenning26-sep-2016
    Plaats van publicatie[Groningen]
    Uitgever
    Gedrukte ISBN's978-90-367-9111-3
    Elektronische ISBN's978-90-367-9110-6
    StatusPublished - 2016

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