Auditory discrimination of highly similar L2 english consonant sounds by blind compared to sighted adult spanish speakers
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Objective: To carry out a pilot experiment so as to draw results and research design improvements supporting the hypothesis that sight deprivation, both for long periods of time and only during moments where auditory information is presented (blindfolding), can lead to better auditory discrimination of highly similar L2 English sounds. Method: 8 late blind adults (age M=36), 8 sighted and blindfolded adults (age M=26), and a control group of 8 sighted and not blindfolded adults (age M=31) participated in this study. All participants were Spanish native speakers of Chilean origin, with little knowledge of the English language. The participants attended five sessions, in which they underwent training stages where they were exposed to English words and nonsense words frequently containing 3 pairs of highly similar English consonant sounds. Two types of minimal pair discrimination tests were administered at the end of each session, with and without background noise. All participants’ levels of exposure to street noise, as well as blind participants’ years of blindness and ages of blindness onset were correlated with their test scores. Results: The three groups showed increases in their scores on the minimal pair discrimination tests throughout the five sessions. The Blind Group tended to outperform the two Sighted Groups, especially in the tests with background noise. A strong correlation was found between the levels of exposure to street noise and the average scores on the auditory discrimination tests with background noise for the Blind and Sighted Blindfolded Groups. A tendency for the B Group’s ages of blindness onset to correlate with their test scores was observed, but no correlation was seen for their number of years of blindness. Conclusions: As expected, blind adults exhibited an enhanced potential to auditorily discriminate the highly similar English consonant sounds selected for this study, compared to the blindfolded and not blindfolded sighted groups. Blind participants’ performance on the minimal pair tests with background noise was higher than any other score in this pilot study, which may be mediated by the levels at which they are generally exposed to street noise, their enhanced capacity for Auditory Scene Analysis 2 (Bregman, 1990) and selective attention, which, in turn, are supported by the neural remodeling that they undergo, as reported in the literature. Although the experimental design yielded results that tend to support the hypothesis of this pilot study, further studies with larger population samples should be carried out to validate these findings.
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