The effect of cue-enhancement on consonant perception by non- native listeners: preliminary results V. Hazan and A. Simpson Department of Phonetics and Linguistics, University College London, London, U.K. v.hazan@phon.ucl.ac.uk, a.simpson@phon.ucl.ac.uk Abstract An experiment was performed to test the perceptual benefits for non-native listeners of enhancing consonantal regions which contain a high density of acoustic cues to phonemic contrasts in English. Groups of Spanish-L1, Japanese-L1 and native English listeners heard nonsense VCV material produced by two different speakers and composed of 12 consonants presented in two vocalic contexts. Both natural and enhanced versions of these stimuli were presented in a background of speech-shaped noise at 0 dB SNR. All three groups of listeners obtained significantly higher intelligibility scores for the enhanced VCVs. They also showed similar speaker effects. Consonant intelligibility scores are discussed in relation to the confusions expected on the basis of the phonological system of the listeners’ L1. 1. Introduction Introduction Second language (L2) learners may experience great difficulty in discriminating and identifying phonemes which are different to those in their native language (for a review, see [1]). Even when they are functioning at a very high level of proficiency in the second language, non-native listeners have been found to show poorer intelligibility of speech in noise than native listeners. For example, using the Modified Rhyme Test, Takata and Nabelek [2] found that Japanese-L1 and native English listeners obtained near-ceiling intelligibility scores in quiet, but that these reduced by 19% for the native listeners in conditions of degradation and by 25% for the Japanese-L1 listeners. In a study on sentence perception, Mayo, Florentine and Buus [3] found significant differences in the perception of sentences in noise between early (before 6) and late (after 14) learners of English although all scored at least 96% correct in quiet. The issue of the perception of noise-degraded speech is very much at the core of our concurrent work on cue- enhancement. In this work, we increase the salience of regions containing acoustic cues to consonant identity in clear speech in order to make the signal more robust to subsequent degradation by noise (e.g. [4]). Significant increases in intelligibility have been reported for native listeners presented with cue-enhanced nonsense words and sentences in noise. The aim of this study was to test whether these enhancements would also be successful in improving consonant intelligibility for non-native listeners. In order not to confound the effects of both acoustic and contextual information, listeners were tested on consonant perception using nonsense word material which is devoid of contextual information. The aims of this study were to investigate: (a) whether L2 learners would benefit from cue-enhancement and whether the extent of any benefit differed from that obtained with native listeners; (b) whether L2 learners would show the same speaker effect as native listeners and (c) whether factors such as L1 background, age of learning (AOL) and length of L2 learning (YOS) would be related to the effect of enhancement. In order to evaluate the effect of L1 background on the perception of enhanced English consonants, two groups of listeners with different language backgrounds were selected. 2. Method 2.1 Listeners The experimental group comprised 22 native Japanese listeners and 16 native Spanish listeners who were attending a two-week Summer School in English Phonetics in the UK. All listeners had their permanent residence in their native country and had never lived abroad for any significant amount of time. Information was collected via a questionnaire about their language background and self-assessment of fluency and comprehension. All listeners reported normal hearing. For the Japanese group, the median age was 19 years, the median age of L2 learning (AOL) was 13 years, and the median number of years of L2 study (YOS) was 7 years. On a range of 1 (poor) to 7 (excellent), their mean self-assessment of comprehension of English was 2.45 and of English fluency was 2.14. For the Spanish group, the median age was 22 years, the median age of L2 learning was 11 years, and the median number of years of L2 study was 11 years. Their mean self-assessment of comprehension of English was 4.87 and of English fluency was 4.07. The control data was obtained from a group of 18 native English listeners, all students in the first year of a Speech Sciences degree at UCL. The median age for this group was 19 years. 2.2 Test materials 24 vowel-consonant-vowel (VCV) stimuli comprising the consonants / / in the context of the vowels / / were recorded by one male and one female speaker. Both speakers were 29 years old, had south-eastern British English accents and had not