Effects of audio-visual information on the intelligibility of alaryngeal speech

Conclusions
: Results suggest that listeners may benefit more from visual information from speakers with poor baseline speech intelligibility. Results also show similar intelligibility between typical, laryngeal and tracheoesophageal modes of speech. Results should be interpreted with caution, however, as only one speaker from each mode of speech was included. Further research is required to determine the nature of the increase.

from the Journal of Communication Disorders

Speech Intelligibility of Flemish Children as Judged by Their Parents

Objective: Reduced intelligibility is a central concern in speech-impaired children, especially for parents. The main purpose of this study was to develop normative data for the intelligibility of Flemish-speaking boys and girls (age 2;06-5;0 years) as judged by their parents. Additionally, the influence of familiarity, gender and age of the child was determined. Patients and Methods: Word, sentence and story productions of 163 healthy children (83 boys and 80 girls) between 2;06 and 5;0 years were transcribed by their own parents. Speech intelligibility was determined according to the intelligibility index described by Shriberg. Additionally, a panel of 12 unfamiliar judges listened to the recordings of a subgroup of 24 randomly selected children. Results: Speech intelligibility improved with increasing age and was around 90% for children aged 4;6-5;0 years. Boys and girls performed equally on the task. For the intelligibility of words, mothers scored significantly better than unfamiliar listeners did. Conclusion: The reported normative speech intelligibility data provide important reference information for speech pathologists who assess child speech. Moreover, it enables them to measure the effect of a specific therapeutic approach and the spontaneous transfer to daily speech.

from Folia Phoniatrica et Logopaedica

Cognitive-linguistic deficit and speech intelligibility in chronic progressive multiple sclerosis

Methods & Procedures: The Arizona Battery for Communication Disorders of Dementia (ABCD) (Bayles and Tomoeda 1993), The Assessment of Intelligibility of Dysarthric Speech (AIDS) Sentence Intelligibility Task (Yorkston and Beukelman 1984), and the Modified Barthel Activities of Daily Living Index (MBADLI) (Shah 1998) were administered to 24 chronic progressive multiple sclerosis participants with dysarthria. A total of 24 non-neurologically impaired participants, matched for gender, age and education, formed a control group.

Outcomes & Results: For multiple sclerosis participants, linear regression analysis showed a strong association between ABCD and AIDS (β = 0.89, p = 0.005), no association between ABCD and either MBADLI or time since onset, a strong association between AIDS and MBADLI (β = 0.60, p = 0.001), and a trend towards an association between AIDS and time since onset (β = -0.29, p = 0.08). Correlations between the four included ABCD construct scores and between these and the total ABCD score were significant (r>0.60, p<0.01). For each of the 15 included ABCD measures and for the four construct scores and the overall ABCD score, multiple sclerosis and control group performances were significantly different (p0.80).

Conclusions & Implications: The results revealed a strong association between dysarthria, as measured by connected speech intelligibility testing, and cognitive-linguistic deficit, in people with chronic progressive-type multiple sclerosis. While some of the impairments that are associated with multiple sclerosis, including motor speech disorder, may influence performance on the ABCD, the data support the conclusion that marked cognitive-linguistic deficit is present in chronic progressive-type multiple sclerosis patients with dysarthria. Deterioration was global, rather than being indicative of a construct specific deficit, and encompassed language, both expression and comprehension. Episodic memory and linguistic expression were especially affected. Speech and language therapists who work with dysarthric patients with chronic progressive multiple sclerosis should monitor cognitive-linguistic impairment. An awareness of this might influence assessment, intervention and management, including the information and advice given to patients and their relatives.

from the International Journal of Language and Communication Disorders

Cognitive-linguistic deficit and speech intelligibility in chronic progressive multiple sclerosis

Methods & Procedures: The Arizona Battery for Communication Disorders of Dementia (ABCD) (Bayles and Tomoeda 1993), The Assessment of Intelligibility of Dysarthric Speech (AIDS) Sentence Intelligibility Task (Yorkston and Beukelman 1984), and the Modified Barthel Activities of Daily Living Index (MBADLI) (Shah 1998) were administered to 24 chronic progressive multiple sclerosis participants with dysarthria. A total of 24 non-neurologically impaired participants, matched for gender, age and education, formed a control group.

Outcomes & Results: For multiple sclerosis participants, linear regression analysis showed a strong association between ABCD and AIDS (β = 0.89, p = 0.005), no association between ABCD and either MBADLI or time since onset, a strong association between AIDS and MBADLI (β = 0.60, p = 0.001), and a trend towards an association between AIDS and time since onset (β = -0.29, p = 0.08). Correlations between the four included ABCD construct scores and between these and the total ABCD score were significant (r>0.60, p<0.01). For each of the 15 included ABCD measures and for the four construct scores and the overall ABCD score, multiple sclerosis and control group performances were significantly different (p0.80).

Conclusions & Implications: The results revealed a strong association between dysarthria, as measured by connected speech intelligibility testing, and cognitive-linguistic deficit, in people with chronic progressive-type multiple sclerosis. While some of the impairments that are associated with multiple sclerosis, including motor speech disorder, may influence performance on the ABCD, the data support the conclusion that marked cognitive-linguistic deficit is present in chronic progressive-type multiple sclerosis patients with dysarthria. Deterioration was global, rather than being indicative of a construct specific deficit, and encompassed language, both expression and comprehension. Episodic memory and linguistic expression were especially affected. Speech and language therapists who work with dysarthric patients with chronic progressive multiple sclerosis should monitor cognitive-linguistic impairment. An awareness of this might influence assessment, intervention and management, including the information and advice given to patients and their relatives.

from the International Journal of Language and Communication Disorders

Ray-tracing prediction of optimal conditions for speech in realistic classrooms

Recent papers have discussed the optimal reverberation times in classrooms for speech intelligibility, based on the assumption of a diffuse sound field. Here this question was investigated for more ‘typical’ classrooms with non-diffuse sound fields. A ray-tracing model was modified to predict speech-intelligibility metric U50. It was used to predict U50 in various classroom configurations for various values of the room absorption, allowing the optimal absorption (that predicting the highest U50)—and the corresponding optimal reverberation time—to be identified in each case. The range of absorptions and reverberation times corresponding to high speech intelligibility were also predicted in each case. Optimal reverberation times were also predicted from the optimal surface-absorption coefficients using Sabine and Eyring versions of diffuse-field theory, and using the diffuse-field expression of Hodgson and Nosal. In order to validate the ray-tracing model, predictions were made for three classrooms with highly diffuse sound fields; these were compared to values obtained by the diffuse-field models, with good agreement. The methods were then applied to three ‘typical’ classrooms with non-diffuse fields. Optimal reverberation times increased with room volume and noise level to over 1 s. The accuracy of the Hodgson and Nosal expression varied with classroom size and noise level. The optimal average surface-absorption coefficients varied from 0.19 to 0.83 in the different classroom configurations tested. High speech intelligibility was, in general, predicted for a wide range of coefficients, but could not be obtained in a large, noisy classroom.

from Applied Acoustics

Cognitive-linguistic deficit and speech intelligibility in chronic progressive multiple sclerosis

Conclusions & Implications: The results revealed a strong association between dysarthria, as measured by connected speech intelligibility testing, and cognitive-linguistic deficit, in people with chronic progressive-type multiple sclerosis. While some of the impairments that are associated with multiple sclerosis, including motor speech disorder, may influence performance on the ABCD, the data support the conclusion that marked cognitive-linguistic deficit is present in chronic progressive-type multiple sclerosis patients with dysarthria. Deterioration was global, rather than being indicative of a construct specific deficit, and encompassed language, both expression and comprehension. Episodic memory and linguistic expression were especially affected. Speech and language therapists who work with dysarthric patients with chronic progressive multiple sclerosis should monitor cognitive-linguistic impairment. An awareness of this might influence assessment, intervention and management, including the information and advice given to patients and their relatives.

from the International Journal of Language and Communication Disorders

Intelligibility of interrupted sentences at subsegmental levels in young normal-hearing and elderly hearing-impaired listeners

Although listeners can partially understand sentences interrupted by silence or noise, and their performance depends on the characteristics of the glimpses, few studies have examined effects of the types of segmental and subsegmental information on sentence intelligibility. Given the finding of twice better intelligibility from vowel-only glimpses than from consonants [Kewley-Port et al. (2007). “Contribution of consonant versus vowel information to sentence intelligibility for young normal-hearing and elderly hearing-impaired listeners,” J. Acoust. Soc. Am. 122, 2365–2375], this study examined young normal-hearing and elderly hearing-impaired (EHI) listeners’ intelligibility of interrupted sentences that preserved four different types of subsegmental cues (steady-states at centers or transitions at margins; vowel onset or offset transitions). Forty-two interrupted sentences from TIMIT were presented twice at 95 dB SPL, first with 50% and second with 70% of sentence duration. Compared to high sentence intelligibility for uninterrupted sentences, interrupted sentences had significant decreases in performance for all listeners, with a larger decrease for EHI listeners. Scores for both groups were significantly better for 70% duration than for 50% but were not significantly different for the type of subsegmental information. Performance by EHI listeners was associated with their high-frequency hearing thresholds rather than with age. Together with previous results using segmental interruption, preservation of vowels in interrupted sentences provides greater benefit to sentence intelligibility compared to consonants or subsegmental cues.

©2009 Acoustical Society of America

from the Journal of the Acoustical Society of America

Language experience and consonantal context effects on perceptual assimilation of French vowels by American-English learners of French

Recent research has called for an examination of perceptual assimilation patterns in second-language speech learning. This study examined the effects of language learning and consonantal context on perceptual assimilation of Parisian French (PF) front rounded vowels /y/ and // by American English (AE) learners of French. AE listeners differing in their French language experience (no experience, formal instruction, formal-plus-immersion experience) performed an assimilation task involving PF /y, , u, o, i, , a/ in bilabial /rabVp/ and alveolar /radVt/ contexts, presented in phrases. PF front rounded vowels were assimilated overwhelmingly to back AE vowels. For PF //, assimilation patterns differed as a function of language experience and consonantal context. However, PF /y/ revealed no experience effect in alveolar context. In bilabial context, listeners with extensive experience assimilated PF /y/ to /ju/ less often than listeners with no or only formal experience, a pattern predicting the poorest /u-y/ discrimination for the most experienced group. An “internal consistency” analysis indicated that responses were most consistent with extensive language experience and in bilabial context. Acoustical analysis revealed that acoustical similarities among PF vowels alone cannot explain context-specific assimilation patterns. Instead it is suggested that native-language allophonic variation influences context-specific perceptual patterns in second-language learning.

©2009 Acoustical Society of America

from the Journal of the Acoustical Society of America

Lexical and indexical cues in masking by competing speech

Three experiments were conducted using the TVM sentences, a new set of stimuli for competing speech research. These open-set sentences incorporate a cue name that allows the experimenter to direct the listener’s attention to a target sentence. The first experiment compared the relative efficacy of directing the listener’s attention to the cue name versus instructing the subject to listen for a particular talker’s voice. Results demonstrated that listeners could use either cue about equally well to find the target sentence. Experiment 2 was designed to determine whether differences in intelligibility among talkers’ voices that were noted when three utterances were presented together persisted when each talker’s sentences were presented in steady-state noise. Results of experiment 2 showed only minor intelligibility differences between talkers’ utterances presented in noise. The final experiment considered how providing accurate and inaccurate information about the target talker’s voice influenced speech recognition performance. This voice cue was found to have minimal effect on listeners’ ability to understand the target utterance or ignore a masking voice.

from the Journal of the Acoustical Society of America

Masking release for low- and high-pass-filtered speech in the presence of noise and single-talker interference

Speech intelligibility was measured for sentences presented in spectrally matched steady noise, single-talker interference, or speech-modulated noise. The stimuli were unfiltered or were low-pass (LP) (1200 Hz cutoff) or high-pass (HP) (1500 Hz cutoff) filtered. The cutoff frequencies were selected to produce equal performance in both LP and HP conditions in steady noise and to limit access to the temporal fine structure of resolved harmonics in the HP conditions. Masking release, or the improvement in performance between the steady noise and single-talker interference, was substantial with no filtering. Under LP and HP filtering, masking release was roughly equal but was much less than in unfiltered conditions. When the average F0 of the interferer was shifted lower than that of the target, similar increases in masking release were observed under LP and HP filtering. Similar LP and HP results were also obtained for the speech-modulated-noise masker. The findings are not consistent with the idea that pitch conveyed by the temporal fine structure of low-order harmonics plays a crucial role in masking release. Instead, any reduction in speech redundancy, or manipulation that increases the target-to-masker ratio necessary for intelligibility to beyond around 0 dB, may result in reduced masking release.

from the Journal of the Acoustical Society of America

Speech recognition by bilateral cochlear implant users in a cocktail-party setting

Unlike prior studies with bilateral cochlear implant users which considered only one interferer, the present study considered realistic listening situations wherein multiple interferers were present and in some cases originating from both hemifields. Speech reception thresholds were measured in bilateral users unilaterally and bilaterally in four different spatial configurations, with one and three interferers consisting of modulated noise or competing talkers. The data were analyzed in terms of binaural benefits including monaural advantage (better-ear listening) and binaural interaction. The total advantage (overall spatial release) received was 2–5 dB and was maintained with multiple interferers present. This advantage was dominated by the monaural advantage, which ranged from 1 to 6 dB and was largest when the interferers were mostly energetic. No binaural-interaction benefit was found in the present study with either type of interferer (speech or noise). While the total and monaural advantage obtained for noise interferers was comparable to that attained by normal-hearing listeners, it was considerably lower for speech interferers. This suggests that bilateral users are less capable of taking advantage of binaural cues, in particular, under conditions of informational masking. Furthermore, the use of noise interferers does not adequately reflect the difficulties experienced by bilateral users in real-life situations.

from the Journal of the Acoustical Society of America

Hybridizing conversational and clear speech to determine the degree of contribution of acoustic features to intelligibility

Speakers naturally adopt a special “clear” (CLR) speaking style in order to be better understood by listeners who are moderately impaired in their ability to understand speech due to a hearing impairment, the presence of background noise, or both. In contrast, speech intended for nonimpaired listeners in quiet environments is referred to as “conversational” (CNV). Studies have shown that the intelligibility of CLR speech is usually higher than that of CNV speech in adverse circumstances. It is not known which individual acoustic features or combinations of features cause the higher intelligibility of CLR speech. The objective of this study is to determine the contribution of some acoustic features to intelligibility for a single speaker. The proposed method creates “hybrid” (HYB) speech stimuli that selectively combine acoustic features of one sentence spoken in the CNV and CLR styles. The intelligibility of these stimuli is then measured in perceptual tests, using 96 phonetically balanced sentences. Results for one speaker show significant sentence-level intelligibility improvements over CNV speech when replacing certain combinations of short-term spectra, phoneme identities, and phoneme durations of CNV speech with those from CLR speech, but no improvements for combinations involving fundamental frequency, energy, or nonspeech events (pauses).

©2008 Acoustical Society of America

from the Journal of the Acoustical Society of America

Perceptual development of phoneme contrasts: How sensitivity changes along acoustic dimensions that contrast phoneme categories

Listeners discriminate acoustic differences between phoneme categories at a higher level than similarly sized differences within phoneme categories. The question this paper aims to answer is how this pattern in perceptual sensitivity develops along an acoustic dimension that contrasts two non-native speech sounds: through acquired distinctiveness, through acquired similarity, or through a combination of the two. A pretest–training–post-test experiment was designed to study perceptual development directly, i.e., by including (i) a discrimination task to measure perceptual sensitivity, (ii) a transfer test to ensure language learning instead of stimulus learning, and (iii) a control group to exclude task repetition as an explanation of improvement. It is shown that the typical peak in perceptual sensitivity near a phoneme boundary that native listeners show is not found in relatively inexperienced language learners, despite their ability to classify a continuum in a nativelike way after short laboratory training. Experiment II indicates that a discrimination peak may be achieved by language learners, but only after much more language experience than short-term laboratory training can offer. Furthermore, reasons are given why classification improvement in the laboratory should not be taken as evidence for (i) increased discrimination of the newly learned phonemes and (ii) learning of phoneme representations.

from the Journal of the Acoustical Society of America

Speech perception of noise with binary gains

For a given mixture of speech and noise, an ideal binary time-frequency mask is constructed by comparing speech energy and noise energy within local time-frequency units. It is observed that listeners achieve nearly perfect speech recognition from gated noise with binary gains prescribed by the ideal binary mask. Only 16 filter channels and a frame rate of 100 Hz are sufficient for high intelligibility. The results show that, despite a dramatic reduction of speech information, a pattern of binary gains provides an adequate basis for speech perception.

from the Journal of the Acoustical Society of America

Effects of Sensorineural Hearing Loss on Visually Guided Attention in a Multitalker Environment

Abstract This study asked whether or not listeners with sensorineural hearing loss have an impaired ability to use top–down attention to enhance speech intelligibility in the presence of interfering talkers. Listeners were presented with a target string of spoken digits embedded in a mixture of five spatially separated speech streams. The benefit of providing simple visual cues indicating when and/or where the target would occur was measured in listeners with hearing loss, listeners with normal hearing, and a control group of listeners with normal hearing who were tested at a lower target-to-masker ratio to equate their baseline (no cue) performance with the hearing-loss group. All groups received robust benefits from the visual cues. The magnitude of the spatial-cue benefit, however, was significantly smaller in listeners with hearing loss. Results suggest that reduced utility of selective attention for resolving competition between simultaneous sounds contributes to the communication difficulties experienced by listeners with hearing loss in everyday listening situations.

from JARO — Journal of the Association for Research in Otolaryngology