非线性频率压缩助听器对听力障碍者言语及音质感知的影响

非线性频率压缩（nonlinear frequency compression,NLFC）技术作为一种创新的降频方案越来越备受关注,该技术主要适用于高频听力损失较重的听力障碍患者,帮助其更好地感知高频信息。本文介绍了NLFC技术的工作原理、对言语感知及音质感知的近期研究进展,并根据目前研究现状对未来研究方向做出展望。     

Impact of frequency compression on music perception

Objective: To determine the effects of frequency compression on music perception, and the impact of previous music training and hearing status. It was hypothesized that lesser amounts of compression would be preferred, and that this pattern of preference would be more evident in the musically trained groups. Design: A paired-comparison paradigm was used. Subjects listened to pairs of musical passages as processed by a hearing aid with different frequency-compression settings. Subjects indicated their preferred passage and the strength of their preference. Study sample: Fifty-seven subjects divided in four groups, according to hearing status (normal hearing, mild-to-moderate hearing loss), and previous music experience (trained, not trained). Results: Subjects generally preferred the conditions with the lesser amount of compression. Listeners in the group with previous music training showed stronger preference for less compression than those without training, as did listeners with normal hearing when compared to subjects with hearing loss. Conclusions: Although less frequency compression was in general preferred, there was more variability in the comparisons involving the default settings for a 50-dB hearing loss (i.e. start frequency 4000 Hz, compression ratio 2.5:1) and no compression, suggesting that mild amounts of compression may not be detrimental to perceived sound quality.     

Aided cortical response,speech intelligibility,consonant perception and functional performance of young children using conventional amplification or nonlinear frequency compression

Objective

The aim of this study was to compare conventional processing with nonlinear frequency compression (NLFC) in hearing aids for young children with bilateral hearing loss.

Methods

Sixty-four children aged between 2 and 7 years with bilateral hearing aids were recruited. Evaluations of cortical responses, speech intelligibility rating, consonant perception and functional performance were completed with the children wearing their personal hearing aids with conventional processing. The children were then refitted with new hearing aids with NLFC processing. Following a six-week familiarization period, they were evaluated again while using their hearing aids with NLFC activated.

Results

The mean speech intelligibility rating and the number of cortical responses present for /s/were significantly higher when children were using NLFC processing than conventional processing in their hearing aids (p < 0.05). Parents judged the children's functional real life performance with the NLFC hearing aids to be similar or better than that with the children's own hearing aids in both quiet and noisy situations. The mean percent consonant score was higher with NLFC processing compared to conventional processing, but the difference did not reach the 5% significance level (p = 0.056). An overall figure of merit (FOM) was calculated by averaging the standardized difference scores between processing schemes for all measures. Regression analysis revealed that, on average, greater advantage for NLFC processing was associated with poorer hearing at 4 kHz.

Conclusions

Compared to conventional processing, the use of NLFC was, on average, effective in increasing audibility of /s/as measured by cortical evaluations, and higher ratings on speech intelligibility and functional performance in real life by parents. On average, greater benefits from NLFC processing was associated with poorer hearing at 4 kHz.     

Improvements in speech perception with an experimental nonlinear frequency compression hearing device

The performance of an experimental frequency compression hearing device was evaluated using tests of speech understanding in quiet. The device compressed frequencies above a programmable cut-off, resulting in those parts of the input signal being shifted to lower frequencies. Below the cut-off, signals were amplified without frequency shifting. Subjects were experienced hearing aid users with moderate-to-severe sensorineural hearing loss and sloping audiograms. Their recognition of monosyllabic words was tested using the experimental device in comparison with conventional hearing aids. Of the 17 subjects, eight showed a significant score improvement (p?<?0.05), whereas one subject showed a significant score decrease. Some of the improvements may have resulted from the better audibility provided in the high frequencies by the experimental device in comparison with the conventional aids. However, a subsequent study found that increasing the high-frequency gain in the conventional aids did not produce equivalent perceptual benefits.     

Electric-acoustic stimulation in adults: localization and speech perception

Abstract

This paper reports findings from a study that was aimed at investigating how best to prescribe devices that provide electric-acoustic stimulation. The localization and speech perception of adults who use electric-acoustic stimulation in one ear and acoustic amplification in the opposite ear were evaluated. Results indicated localization benefits when acoustic amplification was used in both ears. Systematic adjustments of the relative output and cross-over frequencies were implemented to determine the settings that optimized outcomes. Results from a case study indicated benefits for localization and speech perception when electric–acoustic stimulation in one ear was combined with a hearing aid in the opposite ear, after acoustic-to-electric levels and cross-over frequencies were optimized.     

Evaluation of nonlinear frequency compression: Clinical outcomes

This study evaluated prototype multichannel nonlinear frequency compression (NFC) signal processing on listeners with high-frequency hearing loss. This signal processor applies NFC above a cut-off frequency. The participants were hearing-impaired adults (13) and children (11) with sloping, high-frequency hearing loss. Multiple outcome measures were repeated using a modified withdrawal design. These included speech sound detection, speech recognition, and self-reported preference measures. Group level results provide evidence of significant improvement of consonant and plural recognition when NFC was enabled. Vowel recognition did not change significantly. Analysis of individual results allowed for exploration of individual factors contributing to benefit received from NFC processing. Findings suggest that NFC processing can improve high frequency speech detection and speech recognition ability for adult and child listeners. Variability in individual outcomes related to factors such as degree and configuration of hearing loss, age of participant, and type of outcome measure.     

非线性频率压缩助听器对耳聋患者噪声下言语识别的影响

目的 探讨非线性频率压缩(nonlinear frequency compression, NLFC)助听器对以汉语普通话为母语的耳聋患者噪声下言语识别的影响,为耳聋患者助听器选配及助听效果评估提供参考.方法 25例以汉语普通话为母语的感音神经性聋患者,均双耳佩戴助听器,根据患者是否有NLFC助听经验分为A、B两组:A组13例有NLFC助听经验,日常使用NLFC技术;B组12例无NLFC助听经验,日常使用传统放大(conventional process, CP)技术.所有患者分别在NLFC和CP条件下进行噪声下句子识别测试,比较其结果.结果 A组患者在NLFC和CP条件下的噪声下言语识别率分别为82.33%±16.06%、76.70%±18.08%,前者高于后者,差异有显著统计学意义(P<0.01);B组分别为83.04%±12.56%、81.79%±20.07%(P=0.19),差异无统计学意义.A组患者在NLFC和CP条件下的高频(4、6、8 kHz)助听听阈分别为53.54±7.30、57.01±6.81 dB SPL,B组分别为57.42±8.38和61.21±7.42 dB SPL,两组NLFC条件下的助听听阈低于CP条件,差异均有统计学意义(P<0.01).经统计学回归处理,患者在NLFC和CP条件下的高频助听听阈差值与言语识别率差值呈线性相关(r=0.63,t=3.89,P=0.007).结论 NLFC技术可改善患者高频可听度及噪声下言语识别,一定的NLFC使用经验可使NLFC助听效果最大化.     

Effect of input compression and input frequency response on music perception in cochlear implant users

Objective: A study was conducted to determine whether modifications to input compression and input frequency response characteristics can improve music-listening satisfaction in cochlear implant users. Design: Experiment 1 compared three pre-processed versions of music and speech stimuli in a laboratory setting: original, compressed, and flattened frequency response. Music excerpts comprised three music genres (classical, country, and jazz), and a running speech excerpt was compared. Experiment 2 implemented a flattened input frequency response in the speech processor program. In a take-home trial, participants compared unaltered and flattened frequency responses. Study sample: Ten and twelve adult Nucleus Freedom cochlear implant users participated in Experiments 1 and 2, respectively. Results: Experiment 1 revealed a significant preference for music stimuli with a flattened frequency response compared to both original and compressed stimuli, whereas there was a significant preference for the original (rising) frequency response for speech stimuli. Experiment 2 revealed no significant mean preference for the flattened frequency response, with 9 of 11 subjects preferring the rising frequency response. Conclusions: Input compression did not alter music enjoyment. Comparison of the two experiments indicated that individual frequency response preferences may depend on the genre or familiarity, and particularly whether the music contained lyrics.     

Effects of noise and reverberation on speech recognition with variants of a multichannel adaptive dynamic range compression scheme

Abstract

Objective: Adaptive compression methods in hearing aids have been developed to maximise audibility while preserving temporal envelope modulations. Increasing the number of channels may improve listening comfort for loud sounds. However, the effects of this on speech recognition in different environmental conditions are unknown. This study evaluated the effects of different channel architectures and adaptive compression properties on speech recognition in noise and reverberation.

Design: Sentences were mixed with steady or modulated noise at three signal-to-noise ratios (SNRs). These were processed with and without reverberation and amplified with four proprietary adaptive compression methods or linear amplification.

Study sample: 36 listeners with mild to moderately-severe hearing loss.

Results: Adaptive compression improved speech recognition over linear amplification to a small extent, with no significant differences among methods using 4 or 24 channels or a combination thereof. These effects remained across the different background noise and reverberation conditions.

Conclusions: Increasing the number of channels does not negatively affect speech recognition in noise and reverberation when adaptive compression is used. If future research shows that increasing the number of channels improves listening comfort for loud sounds, these results indicate that adaptive compression methods with as many as 24 channels are viable options for hearing aids.     

Predictors of aided speech recognition,with and without frequency compression,in older adults

Objective: The aim was to investigate whether cognitive and/or audiological measures predict aided speech recognition, both with and without frequency compression (FC). Design: Participants wore hearing aids, with and without FC for a total of 12 weeks (six weeks in each signal processing condition, ABA design). Performance on a sentence-in-noise recognition test was assessed at the end of each six-week period. Audiological (severity of high frequency hearing loss, presence of dead regions) and cognitive (reading span and trail making test scores) measures were obtained and assessed as predictors of sentence-in-noise recognition with and without FC enabled. Study sample: Twelve experienced hearing-aid users (aged 65–84 years old) with moderate-to-severe high-frequency hearing loss took part in the study. Results: The results suggest that both auditory and cognitive factors can be predictive of sentence-in-noise recognition with conventional amplification. However, only auditory factors were significantly correlated with the degree of benefit obtained from FC. Conclusions: The strongest predictor of aided speech recognition, both with and without FC, was high frequency hearing loss. Cognitive performance was also a predictor of benefit from conventional amplification, but not of additional benefit from the use of FC.     

The effect on speech intelligibility of varying compression time constants in a digital hearing aid

The identification of nonsense syllables in quiet and in three types of background (babble, cafeteria and single female speaker) was measured using four hearing aid compression algorithms differing in attack and release time constants, and using linear amplification. The speech level was always 65 dB SPL. The compression algorithms, which were implemented in a Phonak Claro ITE hearing aid, were: (1) ‘very fast’—the attack time was 8 ms and the release time was 32 ms, for all 20 channels; (2) ‘slow–fast’—the attack and release times decreased from 500 ms for low frequencies to about 100 ms for high frequencies; (3) ‘fast–slow’—the attack and release times increased from about 50 ms for low frequencies to 500 ms for high frequencies; and (4) ‘slow+fast’—a very slow-acting gain control signal was combined with a fast-acting gain control signal, for each channel in a 10-channel system. Acoustical stimuli were presented monaurally via a circumaural headphone mounted over the hearing aid. The linear condition did not use the Claro aid; instead, the signal was digitally filtered to implement the Cambridge formula prior to delivery via the earphone. Five subjects with moderate sensorineural hearing loss were tested in a counter-balanced order across conditions. In quiet, performance was best for linear amplification and worst for the slow+fast algorithm. In the presence of background sounds, the highest scores were obtained with the linear-gain Cambridge formula implemented via headphones; a supplementary experiment suggested that this was due to the greater high-frequency gain resulting from the use of this formula. No significant differences were found between scores for the different compression algorithms. We conclude that the intelligibility of speech at a fixed level, presented in background sounds, is not markedly affected by rather substantial variations of the time constants in a multichannel compression system.     

人工耳蜗植入和助听器配戴儿童声调识别的对比实验研究

目的探讨人工耳蜗植入儿童和助昕器配戴儿童在声调识别方面是否存在差异；考查人工耳蜗开机时间、入园康复时间，儿童的年龄、性别等因素对声调识别是否有影响。方法采用《言语听觉反应评估》（evaluation of auditory responses to speech，EARS）中的“封闭式声调测试”作为测试材料．对61名3～6岁聋儿（其中人工耳蜗植入儿童31名，助昕器配戴儿童30名）进行声调识别的测试，利用SPSS软件对结果进行统计分析。结果助昕器配戴儿童在声调识别的精确性上优于人工耳蜗植入聋儿；人工耳蜗开机时间对声调测试成绩没有明显的影响；康复时间、聋儿的年龄和声调测试成绩呈正比；聋儿的性别和声调测试成绩无关。结论助昕设备类型、康复时间、年龄等对声调识别的成绩有一定影响，这些因素之间可能存在相互作用，有待进一步探讨。     

An investigation into the effect of limiting the frequency bandwidth of speech on speech recognition in adult cochlear implant users

The purpose of this study was to investigate the effect of the limited-frequency bandwidth employed by telephones (300-3400 Hz) on speech recognition in adult cochlear implant users. The Four Alternative Auditory Feature (FAAF) test was used in four conditions: unfiltered and in three filtered conditions of 300-4500 Hz, 300-3400 Hz and 300-2500 Hz. Ten subjects implanted with the Nucleus CI24M device and 10 normal-hearing listeners were assessed to examine differences between word discrimination scores in each condition. Scores obtained from the 300-3400-Hz and 300-2500-Hz filtered conditions were significantly worse than those with unfiltered speech for the cochlear implant subjects, decreasing by 17.7% and 21.4%, respectively, from scores with unfiltered speech. By contrast, the normal-hearing listeners did not experience difficulties in discriminating between words in any of the conditions. Analysis of the word errors demonstrated that the reduction in implant subject scores with bandwidth arose from errors in place of articulation. Filtering speech in this way has a significant effect on speech recognition for cochlear implant subjects but not normal-hearing listeners. Hence, the limitations of the normal telephone bandwidth can be expected to have a negative effect on speech recognition for cochlear implant users using the telephone.     

Evaluation of the effects of nonlinear frequency compression on speech recognition and sound quality for adults with mild to moderate hearing loss

Objective: While potentially improving audibility for listeners with considerable high frequency hearing loss, the effects of implementing nonlinear frequency compression (NFC) for listeners with moderate high frequency hearing loss are unclear. The purpose of this study was to investigate the effects of activating NFC for listeners who are not traditionally considered candidates for this technology. Design: Participants wore study hearing aids with NFC activated for a 3–4 week trial period. After the trial period, they were tested with NFC and with conventional processing on measures of consonant discrimination threshold in quiet, consonant recognition in quiet, sentence recognition in noise, and acceptableness of sound quality of speech and music. Study sample: Seventeen adult listeners with symmetrical, mild to moderate sensorineural hearing loss participated. Better ear, high frequency pure-tone averages (4, 6, and 8 kHz) were 60 dB HL or better. Results: Activating NFC resulted in lower (better) thresholds for discrimination of /s/, whose spectral center was 9 kHz. There were no other significant effects of NFC compared to conventional processing. Conclusion: These data suggest that the benefits, and detriments, of activating NFC may be limited for this population.     

Effects of speech signal content and speaker gender on acceptance of noise in listeners with normal hearing

Abstract

Objective: The purpose of this research was to determine if the content and/or speaker gender of a running speech sample affected the acceptance of background noise within a participant. Design: A male and a female recording of the Arizona Travelogue (Cosmos Inc.) and the ipsilateral competing message (ICM) from the synthetic sentence identification with ICM were created and used as the experimental speech signals. Two acceptable noise level measurements were obtained and averaged for each condition. Twenty-one participants rated interest level in the speech sample for each condition. Study Sample: Forty-three listeners with normal hearing participated. Results: Interest level was significantly greater for the ICM than the Arizona Travelogue speech samples, and was significantly greater for female samples. Neither the content of the sample nor the gender of the speaker significantly affected the most comfortable level or the acceptable noise level. Conclusions: Findings suggest that the acceptable noise level can be measured using various types of speech signals for normal-hearing listeners.

Sumario

Objetivo: El propósito de esta investigación fue determinar si el contenido y/o el género del locutor en una muestra de lenguaje corrido afectaba la aceptación del ruido de fondo en un mismo participante. Diseño: Se realizóuna grabación con la participación de un hombre y una mujer del Arizona Travelogue (Cosmos Inc.) y del Mensaje Competitivo Ipsilateral (ICM) de la prueba de identificación de Frases Sintéticas con ICM, y se creó una material que fue utilizado como señal lingûstica experimental. Se obtuvieron dos mediciones de niveles de ruido aceptables y se promediaron para cada condición. Veintiún participantes calificaron el nivel de interés de la muestra de lenguaje para cada condición. Muestra del Estudio: Participaron cuarenta y tres sujetos con audición normal. Resultados: El nivel de interés fue significativamente mayor para las muestras de lenguaje del ICM que para las del Arizona Travelogue y estas fueron significativamente mayores para muestras grabadas por mujeres. Ni el contenido de la muestra ni el género del locutor afectó significativamente el nivel más confortable o el nivel aceptable de ruido. Conclusiones: Los hallazgos sugieren que el nivel aceptable de ruido puede medirse usando varios tipos de señales de lenguaje para oyentes con audición normal.     

Effects of insertion depth on spatial speech perception in noise for simulations of cochlear implants and single-sided deafness

Abstract

Objective: This study evaluated the effects of insertion depth on spatial speech perception in noise for simulations of cochlear implants (CI) and single-sided deafness (SSD). Design: Mandarin speech recognition thresholds were adaptively measured in five listening conditions and four spatial configurations. The original signal was delivered to the left ear. The right ear received either no input, one of three CI simulations in which the insertion depth was varied, or the original signal. Speech and noise were presented at either front, left, or right. Study sample: Ten Mandarin-speaking NH listeners with pure-tone thresholds less than 20?dB HL. Results: Relative to no input in the right ear, the CI simulations provided significant improvements in head shadow benefit for all insertion depths, as well as better spatial release of masking (SRM) for the deepest simulated insertion. There were no significant improvements in summation or squelch for any of the CI simulations. Conclusions: The benefits of cochlear implantation were largely limited to head shadow, with some benefit for SRM. The greatest benefits were observed for the deepest simulated CI insertion, suggesting that reducing mismatch between acoustic and electric hearing may increase the benefit of cochlear implantation.     

Effect of signal processing strategy and stimulation type on speech and auditory perception in adult cochlear implant users

Objective: The objective of this study was to investigate the effects of signal processing strategy on speech understanding and auditory function for adult cochlear implant (CI) users with a focus on the effects of sequential versus paired stimulation.

Design: Within-subjects, repeated measures design was utilised to compare performance between processing strategies and stimulation type on various measures of auditory function and subjective sound quality. Testing with subsequent strategies was completed after a total familiarisation time of two weeks.

Study Sample: Ten post-lingually deafened adult CI users were recruited from a clinical population. Participants had a minimum of 13?months CI experience. Ages ranged from 25–78?years. All participants had long-term experience with the optima strategy; eight with sequential stimulation and two with paired stimulation.

Results: We found no statistically significant effect of processing strategy. We observed an effect of stimulation type with sequential stimulation yielding significantly higher performance than paired stimulation for speech understanding in quiet and in noise, and subjective estimates of sound quality. No significant differences were noted across strategy or stimulation for music perception, spectral resolution or temporal resolution.

Conclusions: Many patients utilise paired stimulation – the default stimulation type in the clinical software; however, sequential stimulation yielded significantly higher outcomes on multiple measures.