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PubMed1980

Speech intelligibility in noise with ear protectors.

Speech perception was tested in high level noise under controlled laboratory conditions in noise-exposed workmen and normal subjects, with and without a hearing protector. The group was further divided by age and English fluency, the latter group being included because of the high proportion of non-fluent English speakers in the Canadian workforce. In normal-hearing subjects the highest discrimination scores were found without background noise, they were lower with white noise as a masker, and even lower with crowd noise as a masker; wearing of a protector had no effect on intelligibility. The results for non-fluent English speakers were parallel with these results, but the scores were lower in all test conditions. In the presence of a high frequency hearing loss speech discrimination was lower than in the normals in quiet and in noise. The addition of a hearing protector dropped their discrimination score even further. In a flat hearing loss, wearing of a protector also worsened the speech discrimination score. The results are discussed.

Adult↗
PubMed1999

Speech-intelligibility improvements using a binaural adaptive-scheme based conceptually on human auditory processing.

A speech enhancement scheme is presented using diverse processing in sub-bands spaced according to a human-cochlear describing function. The binaural adaptive scheme decomposes the wide-band input signals into a number of band-limited signals, superficially similar to the treatment the human ears perform on incoming signals. The results of a series of intelligibility and formal listening tests are presented in which acoustic speech signals corrupted with recorded automobile noise were presented to 15 normal hearing volunteer subjects. For the experimental cases considered, the proposed binaural adaptive sub-band processing scheme delivers a statistically significant improvement in terms of both speech-intelligibility and perceived quality when compared with both the conventional wide-band processed and the noisy unprocessed case. The scheme is capable of extension to a potentially more flexible sub-band processing method based on a constrained artificial neural network (ANN).

Acoustic Stimulation↗
PubMed1991

Magnitude-estimation scaling of speech intelligibility: effects of listeners' experience and semantic-syntactic context.

Fifteen speech-language pathologists with extensive experience judging speakers' intelligibility and 15 control subjects with no such previous experience provided magnitude-estimation responses for two sets of nine audiotaped speech samples. These samples were three utterances composed of a group of 17 words that contained all the consonant phonemes of English. These words were arranged to form a set of either meaningful or nonsense utterances. Nine separate versions of both the meaningful and nonsense utterances were created by systematically increasing the number of phonemes produced incorrectly on each of the nine recordings. The analysis indicated no significant difference between the magnitude-estimation scaling responses of experienced and inexperienced listeners. A significant over-all difference was found for listeners' responses to meaningful versus nonsense utterances. The advantages of magnitude-estimation scaling as a measure of speakers' intelligibility are discussed.

Adult↗
PubMed2006

Temporal jitter disrupts speech intelligibility: a simulation of auditory aging.

We disrupted periodicity cues by temporally jittering the speech signal to explore how such distortion might affect word identification. Jittering distorts the fine structure of the speech signal with negligible alteration of either its long-term spectral or amplitude envelope characteristics. In Experiment 1, word identification in noise was significantly reduced in young, normal-hearing adults when sentences were temporally jittered at frequencies below 1.2kHz. The accuracy of the younger adults in identifying jittered speech in noise was similar to that found previously for older adults with good audiograms when they listened to intact speech in noise. In Experiment 2, to rule out the possibility that the reductions in word identification were due to spectral distortion, we also tested a simulation of cochlear hearing loss that produced spectral distortion equivalent to that produced by jittering, but this simulation had significantly less temporal distortion than was produced by jittering. There was no significant reduction in the accuracy of word identification when only the frequency region below 1.2kHz was spectrally distorted. Hence, it is the temporal distortion rather than the spectral distortion of the low-frequency components that disrupts word identification.

Acoustic Stimulation↗
PubMed1997

Development and evaluation of a German sentence test for objective and subjective speech intelligibility assessment.

A German sentence test was developed which is comprised of 20 test lists of ten sentences each. The test corpus is a selection from sentences for speech quality evaluation recorded with a male unschooled speaker. Performance-intensity curves were measured for each individual sentence in a speech-simulating babble noise with a total of 40 normal-hearing listeners. Based on these data and the phonemic transcription of the 200 sentences selected from the underlying speech corpus, 20 test lists were composed using a numerical optimization process. These 20 test lists are highly equivalent with respect to their performance-intensity curves, the number of words within each test list, the number of phonemes within each test list, and approximately the frequency distribution of the phonemes which approximates the phoneme frequency distribution of the German language. The equivalence of the respective performance-intensity curves was demonstrated in an independent experiment with 20 normal-hearing listeners. In addition, a comparison was performed between the "objective" intelligibility measurements and two "subjective" speech intelligibility rating methods employing the same materials. As a result, both subjective assessment procedures correlate highly with each other and with the "objective" procedure across sentences. This underlines the applicability and validity of the test in combination with time-saving subjective assessment methods. Moreover, the variability in performance across different sentences correlates inversely with the RMS level of the respective sentence. This indicates that an adjustment of sentence material with respect to RMS level already yield reasonably homogeneous test material with respect to intelligibility.

Adult↗
PubMed1980

Speech intelligibility in noise-induced hearing loss: effects of high-frequency compensation.

The speech-recognition ability of six listeners with permanent noise-induced hearing losses above 1 kHz was evaluated with the Pascoe High-Frequency Work List spoken by a female talker and presented in the field. In experiment I the words were presented at five intensity levels through five different amplification systems (one with a uniform response and four with increasing amounts of high-frequency emphasis). In experiment II the frequency response of the system associated with the highest scores in experiment I was modified in four ways: elimination of frequences above 6.3 kHz, addition and deletion of 1/3-octave emphasis at the low-frequency boundary of the hearing loss, and addition of 6-dB high-frequency emphasis. The frequency response that was associated with the highest word-identification score for each listener had between 20 and 33 dB more gain in the frequency region of the hearing loss than did the uniform response. Three major factors were found to affect the work-identification scores: audibility of the speech energy, separation of the third-octave-band levels of the words from the discomfort threshold, and balance between the low- and high-frequency levels of the speech signal.

Adolescent↗
PubMedDate not supplied

Most comfortable listening for the loudness and intelligibility of speech.

The effect of instructional set upon most comfortable listening (MCL) was investigated among normal listeners. MCL level and range were determined (method of limits) in relation to listening for comfortable speech loudness versus comfortable speech intelligibility. The results indicate that instructional set does influence listener performance. the mean MCL level for comfortable speech intelligibility was significantly higher (4.96 dB) than the mean level for comfortable speech loudness; the mean MCL range for comfortable speech intelligibility was higher by 7.33 dB and wider by 7.10 dB than the mean range for speech loudness. Ascending stimulus presentation obtained comparable MCL levels for both listening conditions, whereas descending presentation obtained a mean MCL level almost 10 dB higher for comfortable speech intelligibility than for comfortable speech loudness. Males achieved slightly higher MCL levels than did females for both loudness (4.32 dB) and intelligibility (4.96 dB) criteria. It was concluded that the nature of the instructional set be taken into account when interpreting comfortable listening measures.

Adolescent↗
PubMed1998

Influence of communication mode on speech intelligibility and syntactic structure of sentences in profoundly hearing impaired French children implanted between 5 and 9 years of age.

OBJECTIVE: The purpose of this study was to examine the speech production in French profoundly hearing impaired children, focusing on word intelligibility, sentences syntax, and sentence pattern stages, by incorporating direct comparisons between speech production skills and communication modes in the same children. DESIGN: The design of the study incorporated a within-subject, repeated measures design for assessing speech production intelligibility and syntax. SETTING: Montpellier Pediatric Cochlear Implant Center. SUBJECTS: Twelve prelingually deafened French children who received a Nucleus multichannel cochlear implant (mean age at the time of implantation was 7 years 2 months) served as subjects for the speech production assessment. MAIN OUTCOME MEASURES: Speech production intelligibility, syntax, and sentence pattern stages were assessed at 1, 2 and 3 years postimplant. Speech production skills were related to the communication mode of the children (auditory-oral, four children; cued-speech, four children; sign-language, four children). RESULTS: Scores on word intelligibility steadily improved with increased experience with the implant, ranging from 18% before implantation to 54.5% at 36 months postimplantation in the overall population. The highest scores were found in the cued-speech group with an averaged score of 66.8% at 36 months postimplant. The number of syntactic elements increased over time with implant experience. Children receiving cued-speech education had higher scores by 3 years postimplantation than children receiving either auditory-oral or sign-language modes of communication. Language level (sentence pattern stages) also improved with increased experience with the device. By 3 years postimplantation, children receiving auditory-oral or cued-speech instruction were able to produce sentences; however, the sign-language children failed to do so at a rate comparable to the other children. Language level was significantly higher in the oralist or cued-speech educated children than in the sign-language group. CONCLUSIONS: Speech production skills improved with increased experience using a cochlear implant. Word intelligibility, syntactic structure of sentences, sentence pattern stages improved gradually over time. Production skills were greater in the cued-speech educated children group than in the auditory oral or sign-language groups. Statistically better sentence pattern stages were found in the auditory oral and sign-language groups.

Child↗
PubMed2002

Quantifying the intelligibility of speech in noise for non-native listeners.

When listening to languages learned at a later age, speech intelligibility is generally lower than when listening to one's native language. The main purpose of this study is to quantify speech intelligibility in noise for specific populations of non-native listeners, only broadly addressing the underlying perceptual and linguistic processing. An easy method is sought to extend these quantitative findings to other listener populations. Dutch subjects listening to Germans and English speech, ranging from reasonable to excellent proficiency in these languages, were found to require a 1-7 dB better speech-to-noise ratio to obtain 50% sentence intelligibility than native listeners. Also, the psychometric function for sentence recognition in noise was found to be shallower for non-native than for native listeners (worst-case slope around the 50% point of 7.5%/dB, compared to 12.6%/dB for native listeners). Differences between native and non-native speech intelligibility are largely predicted by linguistic entropy estimates as derived from a letter guessing task. Less effective use of context effects (especially semantic redundancy) explains the reduced speech intelligibility for non-native listeners. While measuring speech intelligibility for many different populations of listeners (languages, linguistic experience) may be prohibitively time consuming, obtaining predictions of non-native intelligibility from linguistic entropy may help to extend the results of this study to other listener populations.

Adolescent↗
PubMed1995

Speech intelligibility assessment in a helium environment.

The purpose of this study was to compare the appropriateness and effectiveness of the speech perception in noise (SPIN) test and the Griffiths version of the modified rhyme test (GMRT) in assessing Navy divers' speech understanding using communication systems containing different helium speech unscramblers (HSUs), one of which produces, by subjective observations, more intelligible output than the other. Divers participating in a saturation deep dive and a group of nondivers using digital audio tape recordings of the stimuli used by the divers were tested. Mean percent correct scores on the SPIN and GMRT lists within two listening conditions (taped, topside-diver and live-voice, diver-diver) were almost identical. Listeners scored better on both tests in the topside-diver condition than in the diver-diver condition. The majority of the SPIN errors were on low-predictability items that are void of context. Context clearly played a role in measuring the performance of these subjects, at least for the SPIN test. No significant differences were measured between the two HSUs, although a trend was seen favoring one HSU over the other for the divers. These results have theoretical as well as practical value for measuring the quality and intelligibility of helium speech enhancement systems.

Adult↗