An Italian matrix sentence test for the evaluation of speech intelligibility in noise

Objective: Development of an Italian matrix sentence test for the assessment of speech intelligibility in noise. Design: The development of the test included the selection, recording, optimization with level adjustment, and evaluation of speech material. The training effect was assessed adaptively during the evaluation measurements with six lists of 20 sentences, using open- and closed-set response formats. Reference data were established for normal-hearing listeners with adaptive measurements. Equivalence of the test lists was investigated using the open-set response format at three signal-to-noise ratios (SNRs). Study sample: A total of 55 normal-hearing Italian mother-tongue listeners. Results: The evaluation measurements at fixed SNRs resulted in a mean speech reception threshold (SRT) of ? 7.3 ± 0.2 dB SNR and slope of 13.3 ± 1.2 %/dB. The major training effect of 1.5 dB was observed for the first two consecutive measurements. Mean SRTs of ? 6.7 ± 0.7 dB SNR and ? 7.4 ± 0.7 dB SNR were found from the third to the sixth adaptive measurement for open- and closed-set test response formats, respectively. Conclusions: A good agreement has been found between the SRTs and slope and those of other matrix tests. Since sentences are difficult to memorize, the Italian matrix test is suitable for repeated measurements.     

Study of the noise spectrum on high frequency thresholds in workers exposed to noise

Noise level can be quantified and qualified based on sound characteristics such as intensity, type of spectrum, duration and distribution of the noise exposure during one's working hours.Objective: To assess noise spectrum and the audiometric configuration of workers.Materials and Methods: Contemporary cross-sectional cohort carried out in the Federal District Brazil. We did an environmental analysis (spectral analysis) of the noise in companies from different industries, with audiological assessment of 347 workers.Results: The spectral analysis revealed peaks at different frequencies for each industry investigated (8 kHz-metallurgical, 4 kHz-stone Works and 2 kHz-wood works). We noticed that the frequencies of 14 kHz and 16 kHz had significant differences between the various industries, with a greater prevalence of the metallurgical.Conclusion: The use of noise pressure measuring device, coupled to a frequency analyzer and high frequency audiometric assessment yielded an early detection of hearing damage, helping better organize preventive measures.     

Speech intelligibility in stapedectomized individuals

We assessed the types of speech errors made in relation to the acoustic reflex. Ten subjects with unilateral stapedectomies were presented with consonant-vowel nonsense syllables in low pass noise at 70, 95, and 110 dB SPL in each ear. Hearing sensitivity for all subjects was normal or near-normal bilaterally. In the operated ear, speech intelligibility was significantly poorer than in the unoperated ear at all intensity levels. A distinctive feature analysis supported this finding. The data suggest that word discrimination testing in quiet does not adequately reveal the success of stapedectomy surgery. The distinctive feature analysis indicated that rather than consider the acoustic reflex as limiting the forward spread of masking into high frequencies, it would be better to describe it as a general aural overload regulator.     

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.     

Speech recognition according to the length of hearing aid use

The use of hearing aids can provide plasticity to the hearing system as well as improve speech recognition as time goes by.AimTo compare the influence of the length of hearing aid use on the benefit obtained with the hearing aids in adults and the elderly, new hearing aids users.Materials and methodsProspective study with 40 individuals with mild to moderate-severe sensorineural hearing loss, gathered in 2 groups: Adults Group – 13 people aged between 28 and 59 years old; and Elderly Group – 27 people aged between 61 and 78 years old. These people were assessed 14 and 90 days after hearing aid fitting. Sentence recognition threshold in silence and under noise as well as the percentage indexes of sentences recognition in silence and under noise were obtained.ResultsThe comparison between values obtained after 14 and 90 days of hearing aid use did not show statistically significant differences. When comparing values between the groups, no statistically significant difference was observed either.ConclusionWe did not find influences of the length of hearing aid use and the benefit obtained from using them; the results achieved by adults and the elderly were similar.     

The simplified French Matrix. A tool for evaluation of speech intelligibility in noise

IntroductionIn audiology, the usual tests of speech perception in silence are non-predictive of intelligibility in noise. The French Matrix was developed to assess intelligibility in noise in adults with normal cognitive capacity. A simplified adaptive version, FRA-SIMAT, was derived for use with children and elderly persons with diminished memory span. The aim of the present study was to apply this adaptive procedure to determine signal-to-noise ratio (SNR) according to percentage intelligibility.MethodsTwenty normal-hearing adults and 60 normal-hearing children aged 5–6 years (G1), 7–8 years (G2) and 9–10 years (G3) were included. FRA-SIMAT uses groups of 3 words, to limit memory demand.ResultsIn adults, SNR for 50% (SNR-50) and 80% intelligibility (SNR-80) was respectively −7.1 ± 1.4 dB and −3.7 ± 1.6 dB. In children, SNR-50 was −4.2 ± 1.3 dB in G1, −4.6 ± 1.2 dB in G2, and −5.5 ± 1.5 dB in G3.ConclusionThe FRA-SIMAT test of speech perception in noise was validated in adults and children of different ages, and can be implemented as a diagnostic and rehabilitation tool in clinical practice.     

Development of a Dutch matrix sentence test to assess speech intelligibility in noise

Abstract

Objective: A Dutch matrix sentence test was developed and evaluated. A matrix test is a speech-in-noise test based on a closed speech corpus of sentences derived from words from fixed categories. An example is “Mark gives five large flowers.” Design: This report consists of the development of the speech test and a multi-center evaluation. Study sample: Forty-five normal-hearing participants. Results: The developed matrix test has a speech reception threshold in stationary noise of ? 8.4 dB with an inter-list standard deviation of 0.2 dB. The slope of the intelligibility function is 10.2 %/dB and this is slightly lower than that of similar tests in other languages (12.6 to 17.1 %/dB). Conclusions: The matrix test is now also available in Dutch and can be used in both Flanders and the Netherlands.     

Effects of a transient noise reduction algorithm on speech intelligibility in noise,noise tolerance and perceived annoyance in cochlear implant users

Objective: To evaluate the validity and efficacy of a transient noise reduction algorithm (TNR) in cochlear implant processing and the interaction of TNR with a continuous noise reduction algorithm (CNR). Design: We studied the effects of TNR and CNR on the perception of realistic sound samples with transients, using subjective ratings of annoyance, a speech-in-noise test and a noise tolerance test. Study sample: Participants were 16 experienced cochlear implant recipients wearing an Advanced Bionics Naida Q70 processor. Results: CI users rated sounds with transients as moderately annoying. Annoyance was slightly, but significantly reduced by TNR. Transients caused a large decrease in speech intelligibility in noise and a moderate decrease in noise tolerance, measured on the Acceptable Noise Level test. The TNR had no significant effect on noise tolerance or on speech intelligibility in noise. The combined application of TNR and CNR did not result in interactions. Conclusions: The TNR algorithm was effective in reducing annoyance from transient sounds, but was not able to prevent a decreasing effect of transients on speech understanding in noise and noise tolerance. TNR did not reduce the beneficial effect of CNR on speech intelligibility in noise, but no cumulated improvement was found either.     

Active noise reduction audiometry: a prospective analysis of a new approach to noise management in audiometric testing

OBJECTIVES: To develop a new method of screening audiometry that reduces the adverse effects of low frequency background noise by using active noise reduction (ANR) headphone technology. DESIGN: Prospective testing within an anechoic chamber evaluated the physical properties of ANR headphones. A prospective clinical crossover study compared standard audiometry with ANR headphone audiometry. METHODS: Bose Aviation X circum-aural ANR headphones were tested for both active and passive attenuation properties in a hemi-anechoic chamber using a head and torso simulator. Thirty-seven otology clinic patients then underwent standard audiometry and ANR audiometry, which was performed in a 30- and/or 40-dB sound field. RESULTS: Objective ANR headphone attenuation levels of up to 12 dB were achieved at frequencies below 2,000 Hz. In standard audiometric testing, 40 dB of narrow-band background noise decreased patient pure tone thresholds by 24 dB at 250 Hz. The use of ANR technology provided 12 dB of additional attenuation. This resulted in a significant improvement in test results despite the 40 dB of background noise (P = <0.001). In a 30-dB sound field, standard audiometric thresholds were shifted down by an average of 12 dB. The use of ANR technology completely attenuated this effect and resulted in a significant improvement in results (P = <0.01). These results were identical to those obtained in a quiet sound booth. CONCLUSIONS: Despite a 30-dB sound field, ANR audiometry can produce an audiogram identical to that obtained in a double-walled sound booth. ANR headphone audiometry improves the sensitivity of audiometric screening for mild low-frequency hearing loss. This technology may have important applications for screening in schools, industry, and community practices.     

Speech intelligibility of virtual humans

Abstract

The speech intelligibility benefit of visual speech cues during oral communication is well-established. Therefore, an ecologically valid approach of auditory assessment should include the processing of both auditory and visual speech cues. This study describes the development and evaluation of a virtual human speaker designed to present speech auditory-visually. A male and female virtual human speaker were created and evaluated in two experiments: a visual-only speech reading test of words and sentences and an auditory-visual speech intelligibility sentence test. A group of five hearing, skilled speech reading adults participated in the speech reading test whereas a group of young normal-hearing participants (N?=?35) was recruited for the intelligibility test. Skilled speech readers correctly identified 57 to 67% of the words and sentences uttered by the virtual speakers. The presence of the virtual speaker improved the speech intelligibility of sentences in noise by 1.5 to 2?dB. These results demonstrate the potential applicability of virtual humans in future auditory-visual speech assessment paradigms.     

人工耳蜗使用者噪声环境下言语识别能力研究

目的:评估人工耳蜗(CI)植入者在噪声环境下的言语识别能力。方法:利用普通话版噪声下言语测试(MHINT)为言语测试工具,选取22例CI受试者,按照MHINT适应性得分规则,首先确定受试者在噪声下识别50%～74%的句子内容(评分规则3),达到该水平则继续进行75%以上难度内容(评分规则2或规则1),否则停止。获得受试个体在噪声下言语识别能力的语句接受阈、言语识别率和PI function曲线。结果:22例受试者中,5例在噪声下识别能力达80%～90%,3例可达60%～70%,7例达到50%,7例未能达到MHINT评分规则3测试。获得15例受试者的PI function并与听力正常人进行比较。结论:MHINT适应性得分规则测试法,可有效地获得CI植入者在噪声下的言语识别能力。与听力正常者相比,CI植入者的PI function显示右移10dB以上,在噪声环境下仍需要更好的信噪比。     

Perceived listening effort and speech intelligibility in reverberation and noise for hearing-impaired listeners

Objective: The purpose of this study was to assess perceived listening effort and speech intelligibility in reverberant and noisy conditions for hearing-impaired listeners for conditions that are similar according to the speech transmission index (STI). Design: Scaled listening effort was measured in four different conditions at five different STI generated using various relative contributions of noise and reverberant interferences. Intelligibility was measured for a subset of conditions. Study sample: Twenty mildly to moderately hearing-impaired listeners. Results: In general, listening effort decreased and speech intelligibility increased with increasing STI. For simulated impulse responses consisting of white Gaussian noise exponentially decaying in time, a good agreement between conditions of different relative contributions of noise and reverberation was found. For real impulse responses, the STI slightly overestimated the effect of reverberation on the perceived listening effort and underestimated its effect on speech intelligibility. Including the average hearing loss in the calculation of the STI led to a better agreement between STI predictions and subjective data. Conclusion: Speech intelligibility and listening effort provide complementary tools to evaluate speech perception over a broad range of acoustic scenarios. In addition, when incorporating hearing loss information the STI provides a rough prediction of listening effort in these acoustic scenarios.     

A comparison of cochlear implant processing strategies in children using Speech Pattern Audiometry

Abstract

The aim of this study was to use Speech Pattern Audiometry (SPA) to compare phoneme perception performance between SPEAK and ACE processing strategies with children using the Nucleus 24 cochlear implant. Listeners were evaluated in terms of ability to identify two synthetic word pairs, one signalling a voicing contrast and the other signalling a place of articulation contrast. For both word pairs, ACE was associated with more ‘normal’ phoneme boundaries than SPEAK. There was also a nonsignificant trend for better identification ability with ACE compared to SPEAK. The study suggests that there may be a place for SPA as part of the clinical battery of tests used for evaluation of cochlear implant speech processing strategies in children. Copyright © 2005 John Wiley & Sons, Ltd.     

Audiological evaluation in workers exposed to noise and pesticide

Noise-induced hearing loss has been studied for many years and today many experts also investigate the synergic action of chemical products, since they can be potentially ototoxic.Aimto investigate the audiological findings in workers exposed to occupational noise and pesticide and to compare it to data from noise-exposed workers.Study DesignClinical retrospective.Material and Methodindividuals that had been exposed to pesticide and noise (group I), and individuals that had been exposed to noise only (group II).ResultsThe classification of the audiometric findings showed in that group I: 35% had normal hearing thresholds, 53.75% had degree 1 hearing loss and 11.25% had degree 2 hearing loss; and group II had 57.5% of normal hearing, 40% had degree 1 hearing loss and only 2.5% had degree 2 hearing loss. The analysis of the audiometric findings also showed a significant worsening after comparing groups I and II thresholds, in the frequency of 3 kHz on the left ear and 4 kHz on both ears.ConclusionThe analysis showed that group I had worse audiometric thresholds compared to group II.     

P300 in workers exposed to occupational noise

The harm upon the central auditory pathways of workers exposed to occupational noise has been scarcely studied.ObjectiveTo assess the central auditory pathways by testing the long latency auditory evoked potentials (P300) of individuals exposed to occupational noise and controls.MethodThis prospective study enrolled 25 individuals with normal hearing thresholds. The subjects were divided into two groups: individuals exposed to occupational noise (13 subjects; case group) and individuals not exposed to occupational noise (12 subjects; control group). The P300 test was used with verbal and non-verbal stimuli.ResultsNo statistically significant differences were found between ears for any of the stimuli or between groups. The groups had no statistically significant difference for verbal or non-verbal stimuli. Case group subjects had longer latencies than controls. In qualitative analysis, a greater number of altered P300 test results for verbal and non-verbal stimuli was seen in the case group, despite the absence of statistically significant differences between case and control subjects.ConclusionIndividuals exposed to high sound pressure levels had longer P300 latencies in verbal and non-verbal stimuli when compared to controls.     

Speech and music perception with the new fine structure speech coding strategy: preliminary results

Conclusions. Taking into account the excellent results with significant improvements in the speech tests and the very high satisfaction of the patients using the new strategy, this first implementation of a fine structure strategy could offer a new quality of hearing with cochlear implants (CIs). Objective. This study consisted of an intra-individual comparison of speech recognition, music perception and patient preference when subjects used two different speech coding strategies with a MedEl Pulsar CI: continuous interleaved sampling (CIS) and the new fine structure processing (FSP) strategy. In contrast to envelope-based strategies, the FSP strategy also delivers subtle pitch and timing differences of sound to the user and is thereby supposed to enhance speech perception in noise and increase the quality of music perception. Patients and methods. This was a prospective study assessing performance with two different speech coding strategies. The setting was a CI programme at an academic tertiary referral centre. Fourteen post-lingually deaf patients using a MedEl Pulsar CI with a mean CI experience of 0.98 years were supplied with the new FSP speech coding strategy. Subjects consecutively used the two different speech coding strategies. Speech and music tests were performed with the previously fitted CIS strategy, immediately after fitting with the new FSP strategy and 4, 8 and 12 weeks later. The main outcome measures were individual performance and subjective assessment of two different speech processors. Results. Speech and music test scores improved statistically significantly after conversion from CIS to FSP strategy. Twelve of 14 patients preferred the new FSP speech processing strategy over the CIS strategy.     

Speech Perception with Noise Vocoding and Background Noise: An EEG and Behavioral Study

This study explored the physiological response of the human brain to degraded speech syllables. The degradation was introduced using noise vocoding and/or background noise. The goal was to identify physiological features of auditory-evoked potentials (AEPs) that may explain speech intelligibility. Ten human subjects with normal hearing participated in syllable-detection tasks, while their AEPs were recorded with 32-channel electroencephalography. Subjects were presented with six syllables in the form of consonant-vowel-consonant or vowel-consonant-vowel. Noise vocoding with 22 or 4 frequency channels was applied to the syllables. When examining the peak heights in the AEPs (P1, N1, and P2), vocoding alone showed no consistent effect. P1 was not consistently reduced by background noise, N1 was sometimes reduced by noise, and P2 was almost always highly reduced. Two other physiological metrics were examined: (1) classification accuracy of the syllables based on AEPs, which indicated whether AEPs were distinguishable for different syllables, and (2) cross-condition correlation of AEPs (r_cc) between the clean and degraded speech, which indicated the brain’s ability to extract speech-related features and suppress response to noise. Both metrics decreased with degraded speech quality. We further tested if the two metrics can explain cross-subject variations in their behavioral performance. A significant correlation existed for r_cc, as well as classification based on early AEPs, in the fronto-central areas. Because r_cc indicates similarities between clean and degraded speech, our finding suggests that high speech intelligibility may be a result of the brain’s ability to ignore noise in the sound carrier and/or background.