The contribution of consonants versus vowels to word recognition in fluent speech

Abstract

Three perceptual experiments were conducted to test the relative importance of vowels versus consonants to recognition of fluent speech. Sentences were selected from the TIMIT corpus to obtain approximately equal numbers of vowels and consonants within each sentence and equal durations across the set of sentences. In experiments 1 and 2, subjects listened to (a) unaltered TIMIT sentences, (b) sentences in which all of the vowels were replaced by noise, or (c) sentences in which all of the consonants were replaced by noise. The subjects listened to each sentence five times, and attempted to transcribe what they heard. The results of these experiments show that recognition of words depends more upon vowels than consonants—about twice as many words are recognized when vowels are retained in the speech. The effect was observed when occurrences of [l], [r], [w], [y] [m], and [n] were included in the sentences (experiment 1) or replaced by noise (experiment 2). Experiment 3 tested the hypothesis that vowel boundaries contain more information about the neighboring consonants than vice versa.

Assessing the perceptual contributions of vowels and consonants to Mandarin sentence intelligibility

“…Fig. 2 show that vowels contribute more than consonants to Mandarin sentence intelligibility (i.e., V-only condition versus C-only condition); this is consistent with previous findings obtained in studies with English (e.g., Cole et al, 1996;KewleyPort et al, 2007). This suggests that the intelligibility advantage of vowels is not restricted to English but also found in Mandarin, which is a tonal language.…”

“…2(b)]. This finding is different from that in English studies because the vowel-only condition never had more than 90% intelligibility in those studies (e.g., Cole et al, 1996;Kewley-Port et al, 2007). This suggests that the vowel-only condition is sufficient for listeners to identify Mandarin sentences with consonants replaced by noise.…”

“…In English, vowels were found to have a 2:1 intelligibility advantage over consonants (e.g., Cole et al, 1996;Kewley-Port et al, 2007). However, Mandarin vowels were found to have a 3:1 intelligibility advantage over consonants in this study (i.e., 99.0% vs 34.1%).…”

“…These studies have produced evidence of greater contributions by consonants under some conditions (e.g., Owens et al, 1968;Cutler et al, 2000;Bonatti et al, 2005;Owren and Cardillo, 2006) and greater contributions by vowels under other conditions (e.g., Cole et al, 1996;Kewley-Port et al, 2007;Fogerty and Kewley-Port, 2009). Cole et al (1996) replaced vowel or consonant segments with speech-shaped noise in sentences taken from the TIMIT corpus. This process is known as the "noisereplacement paradigm."…”

“…Vowels are characterized by a relatively open vocal tract with sustained voicing in production and low frequency energy and long duration, whereas consonants are characterized by complete or partial vocal tract constriction in production and high frequency energy and short duration. A number of studies have attempted to investigate the perceptual contributions of vowels and consonants to speech (e.g., word and sentence) intelligibility (e.g., Owens et al, 1968;Cole et al, 1996;Cutler et al, 2000;Bonatti et al, 2005;Owren and Cardillo, 2006;Kewley-Port et al, 2007;Fogerty and Kewley-Port, 2009). These studies have produced evidence of greater contributions by consonants under some conditions (e.g., Owens et al, 1968;Cutler et al, 2000;Bonatti et al, 2005;Owren and Cardillo, 2006) and greater contributions by vowels under other conditions (e.g., Cole et al, 1996;Kewley-Port et al, 2007;Fogerty and Kewley-Port, 2009).…”