Several experiments investigate voicing judgments in minimal pairs like rabid-rapid when the duration of the first vowel and the medial stop are varied factorially and other cues for voicing remain ambiguous. In Experiments 1 and 2, in which synthetic labial and velar-stop voicing pairs are investigated, the perceptual boundary along a continuum of silent consonant durations varies in constant proportion to increases in the duration of the preceding vocalic interval.In Experiment 3, it is shown that speaking tempo external to the test word has far smaller effects on a closure duration boundary for voicing than does the tempo within the test word. Experiment 4 shows that, even within the word, it is primarily the preceding vowel that accounts for changes in the consonant duration effects. Furthermore, in Experiments 3 and 4, the effects of timing outside the vowel-consonant interval are independent of the duration of that interval itself. These findings suggest that consonant/vowel ratio serves as a primary acoustic cue for English voicing in syllable-final position and imply that this ratio possibly is directly extracted from the speech signal.Twenty-five years ago, Denes (1955) reported an interesting phenomenon regarding the perception of phonological voicing by English listeners. He found that a voiceless final fricative in a synthetically constructed monosyllable could be heard as having either the plus or minus value of the English voicing feature, depending on the relative duration of the vowel and final fricative itself for words like his and hiss.

Japanese has long been described as a "mora-timed" language by linguists. Japanese pedagogy has traditionally claimed that moras are constant in duration. Four experiments are reported investigating segmental timing in Japanese in order to test several straightforward hypotheses about mora timing. First, it is demonstrated that words with an increasing number of moras increase in duration by nearly constant increments. The next two experiments explored the mechanisms by which constant mora durations are achieved given that there are large universal differences in the inherent duration of various segment types (e.g., /u/vs/a/), and given that some syllables are supposed to be two mora long (such as, those with long vowels or final consonants). In each case, it was found that the duration of a word stays very close to a target duration that depends on the number of moras in it. This is achieved by stretching or compressing the duration of neighboring segments and adjacent moras. Thus increasing the number of segments in two-mora syllables results in lengthening, not the expected shortening, of other segments in the heavier syllable.

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This study compared the intelligibility of native and foreign-accented bilingualism English speech presented in quiet and mixed with three different levels of background noise. Two native American English speakers and four native Mandarin Chinese speakers for whom English is a second language each read a list of 50 phonetically balanced sentences (Egan, 1948). The authors speech intelligibility identified two of the Mandarin-accented English speakers as high-proficiency speakers and two as lower proficiency speakers, based on their speech intelligibility in quiet (about 95% and 80%, respectively). Original record-perception ings and noise-masked versions of 48 utterances were presented to monolingual American English speakers. Listeners were asked to write down the words they heard the speakers say, and intelligibility was measured as content words correctly identified. While there was a modest difference between native and high-proficiency speech in quiet (about 7%), it was found that adding noise to the signal reduced the intelligibility of high-proficiency accented speech significantly more than it reduced the intelligibility of native speech. Differences between the two groups in the three added noise conditions ranged from about 12% to 33%. This result suggests that even high-proficiency non-native speech is less robust than native speech when it is presented to listeners under suboptimal conditions.

This study describes the development of a minimal-pairs word list targeting phoneme contrasts that pose difficulty for Mandarin Chinese-speaking learners of English as a second language. The target phoneme inventory was compiled from analysis of phonetic transcriptions of about 800 mono- and polysyllabic English words with examples of all the vowels, diphthongs, and syllable onsets and codas of the language. The Mandarin-specific minimal-pairs list derived from the phonetic transcription analyses contains 190 items. Tape recordings were made of 8 Mandarin speakers reading a randomized version of target items from the minimal-pairs list and a set of 20 sentences. Listeners who were native American English speakers judged the words in a forced-choice task and wrote down what they understood of the sentences. Correlations between listener responses on the forced-choice task and the sentence intelligibility scores showed differences in the strength of the relationship with sentence intelligibility across categories of minimal-pairs contrasts. Multiple regression analysis found listener responses on the minimal-pairs task to account for approximately 76% of the variance in speakers' sentence intelligibility scores, showing that performance on the minimal pairs of the probe list does predict connected speech intelligibility. Analyses of individual contrasts indicate target phonemes most often misperceived by native listeners.