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Results for “Speech Intelligibility”

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PubMed1991

Respiratory dynamics and speech intelligibility in speakers with generalized dystonia.

This study investigated aspects of respiratory function, during quiet breathing and monologue, in six adult dystonic subjects and compared the findings to a control group of four neurologically intact adults. Additionally, breathing dynamics were compared with speech intelligibility. Respiratory inductive plethysmography was used to assess breathing rate, periodicity of the breathing pattern, and inspiratory lung volume. Ear oximetry was used to assess arterial blood oxygen saturation. Speech intelligibility was rated by a panel of five judges. Breathing patterns differed between groups; the dystonic subjects showed a faster breathing rate, less rhythmic breathing pattern, decreased lung volume, and apnealike periods accompanied by a decrease in arterial blood oxygen saturation. These differences were observed during quiet breathing and monologue. Decreased speech intelligibility was strongly related to differences in breathing dynamics.

Adolescent↗

PubMed2004

Speech intelligibility of pediatric cochlear implant recipients with 7 years of device experience.

Speech intelligibility of 24 prelingually deaf pediatric cochlear implant (CI) recipients with 84 months of device experience was investigated. Each CI participant's speech samples were judged by a panel of 3 listeners. Intelligibility scores were calculated as the average of the 3 listeners' responses. The average write-down intelligibility score was 71.54% (SD = 29.89), and the average rating-scale intelligibility score was 3.03 points (SD = 1.01). Write-down and rating-scale intelligibility scores were highly correlated (r = .91, p < .001). Linear regression analyses revealed that both age at implantation and different speech-coding strategies contribute to the variability of CI participants' speech intelligibility. Implantation at a younger age and the use of the spectral-peak speech-coding strategy yielded higher intelligibility scores than implantation at an older age and the use of the multipeak speech-coding strategy. These results serve as indices for clinical applications when long-term advancements in spoken-language development are considered for pediatric CI recipients.

Adolescent↗

PubMed2005

The effect of reduced vowel working space on speech intelligibility in Mandarin-speaking young adults with cerebral palsy.

The purpose of this study was to examine the effect of reduced vowel working space on dysarthric talkers' speech intelligibility using both acoustic and perceptual approaches. In experiment 1, the acoustic-perceptual relationship between vowel working space area and speech intelligibility was examined in Mandarin-speaking young adults with cerebral palsy. Subjects read aloud 18 bisyllabic words containing the vowels /i/, /a/, and /u/ using their normal speaking rate. Each talker's words were identified by three normal listeners. The percentage of correct vowel and word identification were calculated as vowel intelligibility and word intelligibility, respectively. Results revealed that talkers with cerebral palsy exhibited smaller vowel working space areas compared to ten age-matched controls. The vowel working space area was significantly correlated with vowel intelligibility (r=0.632, p<0.005) and with word intelligibility (r=0.684, p<0.005). Experiment 2 examined whether tokens of expanded vowel working spaces were perceived as better vowel exemplars and represented with greater perceptual spaces than tokens of reduced vowel working spaces. The results of the perceptual experiment support this prediction. The distorted vowels of talkers with cerebral palsy compose a smaller acoustic space that results in shrunken intervowel perceptual distances for listeners.

Adolescent↗

PubMedDate not supplied

Relationships among types of speech intelligibility in pediatric users of cochlear implants.

UNLABELLED: Twenty pediatric users of cochlear implants were administered three tests of speech intelligibility: (1) a test of contrast perception intelligibility, (2) a test of contrast production intelligibility, and (3) a test of production sentence intelligibility. Sixty adults with normal hearing served as listener judges for the two speech production tasks, and percent correct scores were generated for each of the three tasks. Correlational analyses showed significant correlations among overall scores for the three tasks. However, scores for individual feature classes from the contrast perception task were not correlated with their corresponding contrast production feature class scores, and only some of the feature class scores were correlated significantly with sentence intelligibility. We conclude that although these three types of intelligibility are related at a gross level, relationships are more tenuous at finer levels of analysis, suggesting that the separate skills may need to be addressed separately in remediation. EDUCATIONAL OBJECTIVES: As a result of this activity, the participant will be able to differentiate various methods for assessing speech intelligibility and describe the relationships among different types of speech intelligibility in pediatric users of cochlear implants.

Child↗

PubMed1999

Near-field speech intelligibility in chemical-biological warfare masks.

It is common knowledge among field personnel that poor speech intelligibility can occur when chemical-biological warfare (CBW) masks are worn: indeed, many users resort to hand signals for person-to-person communicative purposes. This study was conducted in an effort to generate basic information about the problem; its focus was on the assessment of, and comparisons among, the communicative efficiency of seven different CBW units. Near-field word intelligibility was assessed by use of rhyming minimal contrast tests; user and acoustic restrictions were studied by means of diadochokinetic tests and system frequency response. The near-field word intelligibility of six American-designed masks varied somewhat, but overall it was reasonably good; however, a Russian unit did not perform well. Second, three of the U.S. masks were found to produce less physiological restraint than the others, and the Soviet mask produced the greatest physiological restraint. Finally, a few of the CBW masks also exhibited very low levels of acoustic distortion. Accordingly, it was concluded that two of the several configurations studied exhibited superior features. Other factors being equal, they can be recommended for field use and as a basis for the development of future generations of CBW masks. However, it also should be noted that although these devices provided reasonably good speech intelligibility when the listener was close to the talker, they do not appear to do so even at minimal distances.

Adult↗

PubMed2003

Effects of orofacial myofunctional therapy on speech intelligibility in individuals with persistent articulatory impairments.

This study examined the effects of orofacial myofunctional therapy (OMT) on speech intelligibility in adults with persistent articulation impairments. Six adults in the age range of 18-23 years were selected to receive orofacial myofunctional therapy for a period of six weeks. The results showed that five out of six clients made significant progress in oral postures and speech sound production across all three speech production tasks: single words, sentences, and spontaneous speech. Speech intelligibility increased significantly in all clients except the one diagnosed with developmental apraxia of speech. Orofacial myofunctional therapists, speech-language pathologists, and other professionals need to rule out underlying orofacial myofunctional variables when targeting speech sounds for intervention. Speech production tasks may be considered as important measures to understand the efficacy of OMT in clinical settings.

Adolescent↗

PubMed1996

Peaks in the frequency response of hearing aids: evaluation of the effects on speech intelligibility and sound quality.

In a series of experiments, we introduced peaks of 10, 20, and 30 dB, in various combinations, onto a smooth reference frequency response. For each of the conditions, we evaluated speech intelligibility in noise, using a test as developed by Plomp and Mimpen (1979), and sound quality (for both speech and music), using a rating-scale procedure. We performed the experiments with 26 listeners with sensorineurally impaired hearing and 10 listeners with normal hearing. Signal processing was accomplished digitally; for each listener, the stimuli were filtered and subsequently amplified so that the average speech spectrum was well above the threshold of hearing at all frequencies. The results show that, as a result of the introduction of peaks onto the frequency response, speech intelligibility is affected more for the listeners with impaired hearing than for those with normal hearing. Sound-quality judgments tend to be less different between the listener groups. Conditions with 30-dB peaks especially show serious effects on both speech intelligibility and sound quality.

Hearing Aids↗

PubMed1999

Speech intelligibility in aircraft noise as a function of altitude.

UNLABELLED: Few studies have addressed physiological effects of altitude and noise combined, although these two factors are inherent parts of all aviation. Altitude effects on hearing function have mainly been studied using gas mixtures with reduced oxygen content. The results have been inconclusive. HYPOTHESIS: The present study was designed to assess the effect of altitude on speech intelligibility in aircraft noise. The primary hypothesis was that exposure to altitude would produce a detrimental, hypoxic effect on speech intelligibility in noise. METHODS: Eight male subjects with normal hearing were fitted with an aviation headset specially adapted for use with the audiometer. Pure-tone audiometry, as well as speech audiometry in noise, were performed at 0, 10,000, 13,000, and 16,000 ft simulated altitudes in a hypobaric chamber. The four test altitudes were performed double blind with respect to audiometry operator and test subject. Arterial blood gases where measured using an intra-arterial catheter. Tympanometric measurements verified full middle ear equilibration. Noise levels where monitored and logged throughout all experiments. RESULTS AND CONCLUSION: A substantial increase in speech intelligibility in noise due to altitude was evident in our study. The physical effect of barometric pressure on noise causing an increased signal-to-noise ratio was found to greatly outweigh any possible hypoxic detrimental effect.

Adult↗

PubMed2002

Effect of noise and occupancy on optimal reverberation times for speech intelligibility in classrooms.

The question of what is the optimal reverberation time for speech intelligibility in an occupied classroom has been studied recently in two different ways, with contradictory results. Experiments have been performed under various conditions of speech-signal to background-noise level difference and reverberation time, finding an optimal reverberation time of zero. Theoretical predictions of appropriate speech-intelligibility metrics, based on diffuse-field theory, found nonzero optimal reverberation times. These two contradictory results are explained by the different ways in which the two methods account for background noise, both of which are unrealistic. To obtain more realistic and accurate predictions, noise sources inside the classroom are considered. A more realistic treatment of noise is incorporated into diffuse-field theory by considering both speech and noise sources and the effects of reverberation on their steady-state levels. The model shows that the optimal reverberation time is zero when the speech source is closer to the listener than the noise source, and nonzero when the noise source is closer than the speech source. Diffuse-field theory is used to determine optimal reverberation times in unoccupied classrooms given optimal values for the occupied classroom. Resulting times can be as high as several seconds in large classrooms; in some cases, optimal values are unachievable, because the occupants contribute too much absorption.

Acoustics↗

PubMed1996

Consistency among speech parameter vectors: application to predicting speech intelligibility.

Previous researchers interested in physical assessment of speech intelligibility have largely based their predictions on preservation of spectral shape. A new approach is presented in which intelligibility is predicted to be preserved only if a transformation modifies relevant speech parameters in a consistent manner. In particular, the parameters from each short-time interval are described by one of a finite number of symbols formed by quantizing the output of an auditory model, and preservation of intelligibility is modeled as the extent to which a one-to-one correspondence exists between the symbols of the input to the transformation, and those of the output. In this paper, a consistency-measurement system is designed and applied to prediction of intelligibility of linearly filtered speech and speech degraded by additive noise. Results were obtained for two parameter sets: one consisting of band-energy values, and the other based on the ensemble interval histogram (EIH) model. Predictions within a class of transformation varied monotonically with the amount of degradation. Across classes of transformation, the predicted effect of additive-noise transformations was more severe than typical perceptual effects. With respect to the goal of achieving predictions that varied monotonically with human speech-perception scores, performance was slightly better with the EIH parameter set.

Auditory Threshold↗

PubMedDate not supplied

Pediatric speech intelligibility test: performance-intensity characteristics.

Performance-intensity (PI) functions for Pediatric Speech Intelligibility (PSI) test materials were obtained in 40 normal-hearing children between 3 and 6 yrs of age. PSI messages were monosyllabic words and sentences presented in quiet and in the presence of a competing speech message. The message-to-competition ratio was constant across intensity levels: +4 dB (words) and O dB (sentences). Maximum speech intelligibility scores were 100% correct in all children for all conditions. The steepness of the PSI-PI functions, defined by the intensity range yielding performance between 20 and 80%, ranged from 8 to 12 dB. Threshold levels (50% correct) ranged from 21 to 26 dB SPL. With one exception, chronological age did not significantly influence the steepness of PSI-PI functions. The exception was the increasing steepness with increasing age noted for sentences in competition. A significant chronological age developmental trend was noted for all speech threshold results.

Age Factors↗

PubMed2003

Defining a left-lateralized response specific to intelligible speech using fMRI.

Functional imaging studies of language have shown bilateral superior temporal activations in response to 'passive' perception of speech when the baseline condition did not control for the acoustic complexity of speech. Controlling for this complexity demonstrates speech-specific processing lateralized to the left temporal lobe, and our recent positron emission tomography study has emphasized a role for left anterolateral temporal cortex in speech comprehension. This contrasts with the more usual view that relates speech comprehension to left temporal-parietal cortex, the ill-defined area of Wernicke. This study attempted to reconcile these differences, using a more sensitive 3 T functional magnetic resonance imaging system, and a sparse sampling paradigm. We found left lateralized activations for intelligible speech with two distinct foci, one in the anterior superior temporal sulcus and the other on the posterior temporal lobe. Therefore, the results demonstrate that there are neural responses to intelligible speech along the length of the left lateral temporal neocortex, although the precise processing roles of the anterior and posterior regions cannot be determined from this study.

Acoustic Stimulation↗

PubMed1984

Prediction of contextual speech intelligibility from isolated word intelligibility measures.

The purpose of this study was to evaluate the efficacy of two nonlinear formulae posited by Boothroyd (1978) for prediction of contextual intelligibility from measures of isolated word intelligibility with four different sets of speech intelligibility data. Both of Boothroyd's formulae, Pc = 1 - (1 - Pi)2 and Pc = 1 - (1 - Pi)1.5 (1 + Pi), provided excellent fit of measured contextual intelligibility with predicted contextual intelligibility for all sets of data. Attempts to improve correlation coefficients between measured and predicted contextual intelligibility by iterating Boothroyd's suggested exponents did not significantly improve the predictive ability of the original formulae.

Deafness↗

PubMed2001

Using statistical decision theory to predict speech intelligibility. I. Model structure.

This article introduces a new model that predicts speech intelligibility based on statistical decision theory. This model, which we call the speech recognition sensitivity (SRS) model, aims to predict speech-recognition performance from the long-term average speech spectrum, the masking excitation in the listener's ear, the linguistic entropy of the speech material, and the number of response alternatives available to the listener. A major difference between the SRS model and other models with similar aims, such as the articulation index, is this model's ability to account for synergetic and redundant interactions among spectral bands of speech. In the SRS model, linguistic entropy affects intelligibility by modifying the listener's identification sensitivity to the speech. The effect of the number of response alternatives on the test score is a direct consequence of the model structure. The SRS model also appears to predict the differential effect of linguistic entropy on filter condition and the interaction between linguistic entropy, signal-to-noise ratio, and language proficiency.

Decision Making↗

PubMed1994

Speech intelligibility and protective effectiveness of selected active noise reduction and conventional communications headsets.

An experiment was conducted to compare both speech intelligibility and noise attenuation of a conventional passive headset (David Clark H10-76) and an electronic Active Noise Reduction (ANR) headset (Bose Aviation) operated with and without its ANR feature. Modified Rhyme Tests were conducted in pink and tank noise, and with and without bilateral phase reversal between earphones. The Bose ANR unit required a significantly higher speech-to-noise (S/N) ratio in both noise environments than the two passive headset systems to maintain equal intelligibility, in part because of its stronger noise reduction and higher required signal level. Articulation Index calculations corroborated the empirical result that the David Clark afforded comparable intelligibility to the Bose ANR device. Bilateral phase reversal proved to be of no benefit, and pink noise proved to be the harsher environment for speech intelligibility. On a speech intelligibility basis alone, the results do not justify the additional cost of the ANR headset; however, when severe noise exposure is at issue, a properly functioning ANR unit may afford more protection than a similar passive headset without electronics, especially in low-frequency noise spectra.

Acoustics↗

PubMed1981

Bone-conducted speech: intelligibility functions and threshold force levels for spondees.

Threshold force values for spondees were obtained for thirty-six subjects with normal hearing using the Radioear B-70-AA and B-71 bone vibrators, which were coupled to the head with a Radioear P-3333 headband. Measurements were made on a Bruel & Kjaer model 4930 artificial mastoid. In addition to the 1000 Hz calibration tone preceding the spondees, speech noise and white noise were dubbed on the tape at the same level as the tone. Since the results indicated similar threshold force levels for both vibrators, the data from the B-70-AA and B-71 were pooled. These values in dB re 1 micro Newton are 53.2 dB for 1000 Hz, 56.8 dB with white noise, and 62.4 dB using speech noise. Any of these three calibrating signals appear appropriate when delivering speech to the B-70-AA or B-71 bone vibrators. Another purpose of this study was to establish normal speech intelligibility functions for the CID W-22 test using the B-71 vibrator. Sixteen subjects with normal hearing were tested at sensation levels (SLs) ranging from 0 to 34 dB. The results showed that intelligibility scores ranged from about 15 percent at 0 dB SL to 95 percent at 34 dB SL, and that the slope of the intelligibility function systematically decreased with increasing intensity. These findings are typical of speech intelligibility functions obtained via air conduction.

Adult↗

PubMed2002

Effects of high-frequency emphasis and compression time constants on speech intelligibility in noise.

The objectives of the study were to evaluate the effect of different settings with regard to speech intelligibility in noise both objectively and subjectively and thus determine a favoured setting of compression time parameters, pre-set program (high-frequency emphasis) or combination for each individual user in a prospective study. Another objective was to evaluate the relationship between patient characteristics (e.g. slope of hearing loss) and favoured settings. In total, 38 subjects divided over five audiological centres were fitted with the Philips Spaceline D71-40 BTE digital hearing aid. Subjects were asked to compare three predefined compression algorithms with different time constants, slow (indicated by the manufacturer as AVC), intermediate (NORMAL) and fast (SYLLABIC) over two 4-week periods using the intermediate setting in both comparisons and randomizing over the fast and slow conditions. A randomization determined whether a subject started with the comfort-oriented pre-set program (AUTO) or the speech intelligibility-oriented setting with high-frequency emphasis (SPIN). In a third 4-week period, the pre-sets AUTO and SPIN were compared using the setting of the compression time constants that gave the best results during the first two periods. Comparisons were made using a standard speech-in-noise test with three types of noise: continuous speaker noise, modulated ICRA-4 noise, and car noise. The patients were also asked to fill in a Dutch translation and adaptation of the APHAB questionnaire to indicate their impression of performance. The results indicate that no compression algorithm, pre-set or combination is favoured overall. The largest improvement in speech-in-noise scores was found with syllabic compression. The advantageous effect of high-frequency emphasis after optimization of compression timing is small. The APHAB showed that users tend to prefer the SPIN setting. We found no relationship between favoured compression or pre-set and the degree or steepness of the hearing loss User preference and best performance in noise do not always coincide. Acclimatization may play a role. It could be advisable to let a user listen to a subjectively less favoured condition for at least some time if an optimal setting for speech intelligibility in noise is preferred over comfort.

Acoustic Stimulation↗

PubMed1981

Construct validity of direct magnitude estimation and interval scaling of speech intelligibility: evidence from a study of the hearing impaired.

The appropriateness of direct magnitude estimation and interval scaling procedures for assessing the speech intelligibility of hearing-impaired adults was investigated by determining whether the continuum of the talkers' intelligibility was prothetic or metathetic. The intelligibility of 20 hearing-impaired talkers was scaled by 20 listeners using direct magnitude estimation and by 20 listeners using interval scaling. The two sets of scaling data were related in the curvilinear fashion that is typical of prothetic continua, indicating better construct validity for direct magnitude estimation than for interval scaling of speech intelligibility.

Analysis of Variance↗