Consonant-vowel Intensity Ratio Research Articles

Intervocalic /ɡ/ realization in Border Uruguayan Spanish

Abstract In Border Uruguayan Spanish, intervocalic voiced obstruents have been known to be produced as stops due to the variety’s contact with Portuguese. The present study investigates intervocalic /ɡ/ in a corpus of sociolinguistic interviews. Using an acoustic measure, a consonant-vowel intensity ratio, as an index of constriction of /ɡ/, we found that, similar to /b/ and /d/, the speaker’s age, Spanish use, and sex have a strong impact on the realization of intervocalic /ɡ/. Specifically, younger speakers, those that speak Spanish most of the time, and men are likely to use less constricted variants such as approximants and elision. Given the parallels that these results have with findings of studies of intervocalic /d/ and, to a lesser extent, /b/ in this variety, we discuss support for the notion that the three phonemes behave as a series and not independently.

An Acoustic-Phonetic Approach to Effects of Face Masks on Speech Intelligibility.

This study aimed to examine the effects of wearing a face mask on speech acoustics and intelligibility, using an acoustic-phonetic analysis of speech. In addition, the effects of speakers' behavioral modification while wearing a mask were examined. Fourteen female adults were asked to read a set of words and sentences under three conditions: (a) conversational, mask-off; (b) conversational, mask-on; and (c) clear, mask-on. Seventy listeners rated speech intelligibility using two methods: orthographic transcription and visual analog scale (VAS). Acoustic measures for vowels included duration, first (F1) and second (F2) formant frequency, and intensity ratio of F1/F2. For consonants, spectral moment coefficients and consonant-vowel (CV) boundary (intensity ratio between consonant and vowel) were measured. Face masks had a negative impact on speech intelligibility as measured by both intelligibility ratings. However, speech intelligibility was recovered in the clear speech condition for VAS but not for transcription scores. Analysis of orthographic transcription showed that listeners tended to frequently confuse consonants (particularly fricatives, affricates, and stops), rather than vowels in the word-initial position. Acoustic data indicated a significant effect of condition on CV intensity ratio only. Our data demonstrate a negative effect of face masks on speech intelligibility, mainly affecting consonants. However, intelligibility can be enhanced by speaking clearly, likely driven by prosodic alterations.

A real-time wavelet-based algorithm for improving speech intelligibility

A wavelet-based algorithm to improve speech intelligibility is reported. The speech signal is split into frequency sub-bands via a multi-level discrete wavelet transform. Various gains are applied to the sub-band signals before they are recombined to form a modified version of the speech. Dynamic range compression then follows to control the peak amplitude. The sub-band gains are adjusted while keeping the overall signal energy unchanged, and the speech intelligibility under simulated hearing loss conditions and various background interference is enhanced and evaluated objectively and quantitatively using Google Speech-to-Text transcription. For English and Chinese noise-free speech, overall intelligibility is improved, and the transcription accuracy can increase by over 80 percentage points by reallocating the spectral energy toward the mid-frequency sub-bands, effectively increasing the consonant-vowel intensity ratio. This is reasonable since the consonants are relatively weak and of short duration, and are therefore the most likely to become indistinguishable in the presence of background noise or high frequency hearing impairment. For speech already corrupted by noise, improving intelligibility is challenging but still realizable. The proposed algorithm is implementable in real-time and comparatively simpler than previous algorithms. Potential applications include speech transmission, hearing aids, machine listening, and a better understanding of speech intelligibility.

Discrimination thresholds for level increments in the stop-consonant noise bursts of CVC words: Intra-speech masking, temporal-position, temporal-variability, and place-of-articulation effects

Estimates of sensitivity to level differences in stop-consonant noise bursts could help designing speech-processing strategies such as dynamic-range compression and optimal consonant-vowel intensity ratio. In normal-hearing participants, we measured level-discrimination thresholds (LDTs) for the noise bursts of CVC words (/paet/, /paek/, and /kaet/). With /paet/, a 2I-2AFC task measured LDTs for the pre- or post-vocalic burst in isolation or in word context; in the latter, the burst with level increments (pre or post) remained the same or varied unpredictably from trial to trial. In isolation, the 1.98–2.22 dB LDTs approached those of like-duration random noise, but increased to ≈9.0 dB for the pre-vocalic burst in-context, and more so in unpredictable-burst conditions (10.81 dB); for the post-vocalic burst the LDTs increased only slightly. To assess the role of set-size, within-trial standard, and place-of-articulation, the in-context, unpredictable-burst LDTs were measured with single- or two-observation in...

Effects of consonant-vowel intensity ratio on loudness of monosyllabic words

Previous research has suggested that speech loudness is determined primarily by the vowel in consonant-vowel-consonant (CVC) monosyllabic words, and that consonant intensity has a negligible effect. The current study further examines the unique aspects of speech loudness by manipulating consonant-vowel intensity ratios (CVRs), while holding the vowel constant at a comfortable listening level (70 dB), to determine the extent to which vowels and consonants contribute differentially to the loudness of monosyllabic words with voiced and voiceless consonants. The loudness of words edited to have CVRs ranging from -6 to +6 dB was compared to that of standard words with unaltered CVR by 10 normal-hearing listeners in an adaptive procedure. Loudness and overall level as a function of CVR were compared for four CVC word types: both voiceless consonants modified; only initial voiceless consonants modified; both voiced consonants modified; and only initial voiced consonants modified. Results indicate that the loudness of CVC monosyllabic words is not based strictly on the level of the vowel; rather, the overall level of the word and the level of the vowel contribute approximately equally. In addition to furthering the basic understanding of speech perception, the current results may be of value for the coding of loudness by hearing aids and cochlear implants.

Acoustic-phonetic correlates of talker intelligibility for adults and children

This study investigated acoustic-phonetic correlates of intelligibility for adult and child talkers, and whether the relative intelligibility of different talkers was dependent on listener characteristics. In experiment 1, word intelligibility was measured for 45 talkers (18 women, 15 men, 6 boys, 6 girls) from a homogeneous accent group. The material consisted of 124 words familiar to 7-year-olds that adequately covered all frequent consonant confusions; stimuli were presented to 135 adult and child listeners in low-level background noise. Seven-to-eight-year-old listeners made significantly more errors than 12-year-olds or adults, but the relative intelligibility of individual talkers was highly consistent across groups. In experiment 2, listener ratings on a number of voice dimensions were obtained for the adults talkers identified in experiment 1 as having the highest and lowest intelligibility. Intelligibility was significantly correlated with subjective dimensions reflecting articulation, voice dynamics, and general quality. Finally, in experiment 3, measures of fundamental frequency, long-term average spectrum, word duration, consonant-vowel intensity ratio, and vowel space size were obtained for all talkers. Overall, word intelligibility was significantly correlated with the total energy in the 1- to 3-kHz region and word duration; these measures predicted 61% of the variability in intelligibility. The fact that the relative intelligibility of individual talkers was remarkably consistent across listener age groups suggests that the acoustic-phonetic characteristics of a talker's utterance are the primary factor in determining talker intelligibility. Although some acoustic-phonetic correlates of intelligibility were identified, variability in the profiles of the "best" talkers suggests that high intelligibility can be achieved through a combination of different acoustic-phonetic characteristics.

Consonant-vowel intensity ratios for maximizing consonant recognition by hearing-impaired listeners.

The effect of adjusting the consonant-vowel (C-V) intensity ratio on consonant recognition in 18 subjects with sensorineural hearing impairment was investigated. C-V intensity ratios in a set of 48 vowel-consonant nonsense syllables were adjusted in steps of 3-6 dB depending on the subject's dynamic range of hearing. An increase in consonant intensity is referred to here as consonant enhancement (CE). The value of CE producing the highest consonant recognition score (CRmax) is defined as CEmax. Both CEmax and CRmax were determined for each subject for each of the 48 nonsense syllables. Consonant type was found to have a highly significant effect on CRmax, the gain in consonant recognition, and CEmax. The effect of vowel environment was also significant, but of much smaller magnitude. Audiogram configuration was found to have a small effect and was only significant for CRmax. The results of the study also showed that individualized adjustment of the C-V intensity ratio for each subject and consonant-vowel combination can produce substantial improvements in consonant recognition. These data can be used to estimate upper bounds of performance that, in principle, can be obtained by appropriate adjustment of the C-V intensity ratio.

A comparison between the electrically reproduced loudness and the original loudness of speech at high levels

Four words lists of a German Speech Intelligibility Test (DIN 45621) were recorded at 60 and 75 dB SPL. Both recordings were presented to 20 normally hearing subjects at 75 dB SPL via free-field equalized earphones. Discrimination in noise was significantly better in the original recording at 60 dB SPL. The better understanding may be explained by a more favourable consonant-vowel intensity ratio. Moreover, a significant increase in fundamental frequency could be demonstrated at the higher recording level. The implications for speech audiometry and hearing aids are discussed. Furthermore, it was found from loudness comparisons that both recordings were equally loud at a level of 75 dB SPL. However, significantly increased loudness was indicated in the 75 dB SPL recording by the loudness calculation procedure ISO 532 B.

The importance of consonant-vowel intensity ratio in the intelligibility of voiceless consonants.

The purpose of this study was to evaluate the extent to which variations in the consonant-vowel (C-V) intensity ratio could account for variations in speech intelligibility among the productions of 10 talkers. Fifty normal-hearing individuals listened in noise to syllables consisting of voiceless consonants followed by the vowel /a/ under three conditions in which: (a) C-V ratio varied naturally as produced by the talkers, and the stimuli were calibrated according to vowel intensity; (b) C-V ratios were increased and equated via digital signal processing; and (c) C-V ratios were unmodified, but the syllables were calibrated according to consonant level rather than vowel level. Results indicated that variations in C-V ratio explained a great deal of the variation in the intelligibility of some consonants (/s, S, tS/) but not others (the voiceless stops). This difference may well be due to differences in audibility between the two groups of consonants when they are presented at similar consonant-to-noise ratios. The majority of the data suggest that the importance of C-V ratio is related to the intensity of consonants but is independent of the ratio per se between consonant and vowel levels.