方向性麦克风技术在助听器中的应用

引言 目前，助听器的广泛使用已经使广大听力损失患者在很大程度上改善了他们的生活质量，但这些助听器用户在日常生活中还是会有一些聆听上的困难，尤其是在噪声环境下与人交谈。方向性麦克风系统（directional microphones system）也译为指向性麦克风，是用于提高助听器言语信噪比的一项重要技术，尤其能改善在噪声环境下的言语清晰度（可懂度）。本文通过介绍方向性麦克风的原理、作用以及实际应用方面等相关知识来帮助听力从业人员、技术人员和用户更好地了解和使用这项技术。     

方向性助听器的适用人群(听力研究及技术)

简介:助听器生产商对声信号的高保真及混合有了明显的进步并适应了现有的助听器技术发展水平的需要。但是，噪声下的言语理解仍然是助听器使用人群的主要抱怨。(见图1)。     

单通道与多通道自适应方向性麦克风助听器对正常成年人噪声下言语识别率的影响

目的 比较噪声环境下单通道和多通道自适应麦克风助听器的指向性对正常成年人言语识别率的影响.方法 30例(60耳)正常青年人(男、女各15例)分别双耳配戴Diva 9(单通道自适应麦克风指向性模式)和Inteo 9(多通道自适应麦克风指向性模式)耳背机,在不同信噪比的动态噪声漫射声场中进行言语识别率测试,对助听效果进行评估.结果 单通道自适应方向性麦克风(Diva9)及多通道自适应方向性麦克风(Inteo9)L50值[达到50%言语识别率所需的信噪比(dB)]分别为0.63和-4.63 dB,两者比较差异有显著统计学意义(P＜0.001).结论 自适应方向性麦克风系统的多通道极性最优化模式可显著提高配戴者的言语识别能力.     

正常听力受试者佩戴不同组合全向性与方向性麦克风的效果比较

目的 比较噪声环境下全向性麦克风与自适应方向性麦克风的不同组合佩戴方式对听力正常成年人言语识别率的影响,从而选择最佳的组合佩戴方式.方法 选择20例(40耳)听力正常青年人(男、女各10例)分别按照双耳全向性麦克风模式(组合1),双耳自适应方向性麦克风模式(组合2),一耳全向性麦克风、一耳自适应麦克风模式(组合3)3种方式,在信噪比变化的漫射声场中进行言语识别率测试,从而进行助听效果的评估.结果 组合1、2、3三种方式测出的L50值(50%言语识别率的信噪比)分别为-3.55±2.37 dB,-7.15±2.18 dB,-5.40±2.35 dB,三者之间两两比较差异均有显著统计学意义(P<0.05).结论 噪声环境下无论双耳佩戴自适应方向性麦克风模式还是一耳佩戴自适应方向性麦克风、另一耳佩戴全向性麦克风,其言语识别能力均高于双耳佩戴全向性麦克风模式,且双耳佩戴自适应方向性麦克风模式的言语识别率高于一耳自适应麦克风、一耳全向性麦克风模式.     

噪声环境下自适应方向性与全向性麦克风助听模式对言语分辨率的影响

目的比较噪声环境下自适应方向性麦克风与全向性麦克风助听模式对听力损失患者言语识别率的影响。方法 20例双耳对称性感音神经性听力损失患者(男9例,女11例)均单耳佩戴助听器(Resound Canta 780-D),佩戴并适应6个月以上,随机分为两组,每组10例,A组先将助听器麦克风模式切换至全向性,适应2周后测试其在噪声环境下的言语识别率,并完成助听器效果评估表(the abbreviated profile of hearing aid benefit,APHAB)及麦克风效果问卷(microphone performance questionnaire,MPQ);再将麦克风模式切换至自适应方向性,适应2周后重复以上测试。B组麦克风模式切换顺序先为自适应方向性,再为全向性,测试方法同A组。结果声场评估示,噪声环境下,患者使用自适应方向性麦克风助听模式的言语识别率(73.20%±20.69%)高于全向性麦克风模式(64.00%±18.76%),差异有显著统计学意义(P<0.001)。APHAB评估结果显示在有背景噪声、回声、厌恶声存在的环境下,受试者使用自适应方向性麦克风助听模式能更好地提高言语交流能力。MPQ问卷表评估结果显示,除第六类场景(信号来源于听者正前方、无噪声、低混响)外,受试者在其余九类交流场景时使用自适应方向性麦克风助听模式的言语识别率均优于全向性模式。结论噪声环境下自适应方向性麦克风助听模式可显著提高患者的言语识别率。     

骨锚式助听器(BAHA)的临床应用进展

听力障碍是我国常见疾病之一,目前临床上有多种可以提高听力的技术。比如气导助听器、听力重建手术、振动声桥技术、人工耳蜗植入技术、骨桥等。每种技术均有其有限适应症及手术风险。骨锚式助听器(Bone-anchored hearing aid,BAHA),又称骨导听觉植入装置,是一种骨导助听装置,利用骨融合原理,通过骨传导将声音信号传入内耳。本文主要就BAHA的临床应用进展进行综述。     

音响校准和助听器验配:数字技术的新突破

最近，在教授助听器验配时，常常有学生对如何使用助听器验配软件附带的各种声音信号库深感困惑。在临床工作中，许多验配师也不了解声音库的作用和使用方法及验配软件对声音库信号的校准。在临床中遇见的最大问题是如何设置、校准声场的扬声器及使用这些音响设备。从技术发展上看，数字助听器已经广泛使用一些非常有效的先进技术，如自适应指向性技术、降噪、声反馈技术和多通道压缩技术等。[第一段]     

攀登听力学的高峰--来自美国(盐湖城)2004年听力学年会的报道

今年美国听力学的主题为“攀登听力学的高峰”（Audiology Rocks）。这次盛会展现了听力学的最新研究果和最先进的助听器技术，并预示了听力学在未来几年的发展方向。     

配戴助听器对老年性耳鸣的影响(附52例报告)

由耳部病变引起的耳鸣多伴有耳聋 ,耳鸣的治疗因其病因不同而方法各异。配戴助听器后老年性感音性聋在听力改善的同时 ,部分患者的耳鸣症状亦有不同程度的减轻甚至消失。现将本组 5 2例老年性神经性耳鸣患者配戴助听器对耳鸣的治疗效果报告如下。1　资料和方法1 .1 　 临床资料5 2例中 ,男 2 0例 ,女 32例 ;年龄 60～ 80岁。语言频率听力平均损失 >5 0ｄＢＨＬ ,均为感音性聋 ,耳鸣频率多在 30 0 0～ 80 0 0Ｈｚ,响度多在纯音阈上 5～ 2 0ｄＢＨＬ。耳鸣仅出现在安静环境中 (轻度 ) 1 2例 ,在普通环境中有耳鸣 ,安静环境中耳鸣更明显 (中度 …     

助听器领域的最新技术及应用

近十年来，助听器技术不断发展进步，尤其是随着数字技术的采用，实现了助听器技术的飞速发展。在方向性技术．压缩与放大．降噪以及数字反馈抑制方面都取得了不断的进步，为诸多听障人士的听力康复做出了贡献。尽管如此，调查表明，美国只有30%助听器使用者对助听器在噪声环境中的表现是非常满意的，     

Directional hearing aid benefit in listeners with severe hearing loss

The purpose of this investigation was to examine the potential for directional hearing aid benefit in listeners with severe hearing loss at multiple SNRs for both auditory only and audio-visual presentation modes. Speech recognition performance was measured using the connected speech test at six SNRs individually determined for each subject in order to avoid floor and ceiling effects. The results revealed significant directional benefit was present at all tested SNRs in the presence of visual information. For auditory only presentations, significant directional benefit was only present at the least positive SNR. The largest directional benefit was measured at the poorest tested SNR for both auditory only and audio-visual presentation modes. The results of this study generally support small but significant directional for listeners with severe hearing loss benefit in a difficult listening environment both with and without the presence of visual information.

Sumario

El objetivo de esta investigación fue examinar el beneficio potencial de los auxiliares auditivos direccionales en personas con hipoacusia severa en múltiples condiciones de señal/ruido (SNR) tanto en modo auditivo como en audio-visual. Se midió el desempeño en el reconocimiento del lenguaje mediante la prueba de lenguaje conectado a seis diferentes SNR, determinados en cada individuo para evitar el efecto de piso/techo. Los resultados revelan un beneficio direccional significativo en las seis condiciones de prueba en presencia de información visual. En la presentación exclusivamente auditiva, el beneficio sólo se presentó con la SNR menos positiva. El mayor beneficio direccional se midió con la SNR mas pobre tanto en el modo auditivo como en el audio-visual. Los resultados generales de este estudio apoyan que existe un beneficio direccional pequeño pero significativo para personas con hipoacusia severa en ambientes sonoros difíciles, con o sin información visual.     

全自动程序切换助听器技术临床应用的效果评估

目的评估全自动程序切换技术(Liaison Full Shell)助听器在临床中对听力损失患者的康复效果。方法本临床测试是通过助听器使用者的日常经历与临床客观验证来证明被测助听器的效果,采用前后对照试验法,以此保证测试结果的可靠性及客观性。本临床测试是对试验用助听器配戴前后的听力水平和言语理解度做出比较。在配戴试验用助听器前。测出受试者每个人的听力损失类型及程度．言语理解度．不舒适阈,然后听力师根据病人的情况进行验配与调试,每一位受试者配戴每一种试验用助听器不少于3周时间,其间受试者有任何的不适。都应接受听力师的调试。若调试没有效果将中止临床试验。在配戴试验用助听器后,用声场测试受试者配戴助听器后的听阈值,用2cc3耦合腔和真耳测量客观方法验证助听效果。结果在20倒中,平均听阈值提高到35dBHL,在真耳测试中全部达到目标增益和最大输出。在声场测试中。平均功能增益达到60dB HL。结论助听前和助听后的听力阈值明显改善,具有显著性意义。     

Evaluation of model-based versus non-parametric monaural noise-reduction approaches for hearing aids

Abstract

Objective: Single channel noise reduction has been well investigated and seems to have reached its limits in terms of speech intelligibility improvement, however, the quality of such schemes can still be advanced. This study tests to what extent novel model-based processing schemes might improve performance in particular for non-stationary noise conditions. Design: Two prototype model-based algorithms, a speech-model-based, and a auditory-model-based algorithm were compared to a state-of-the-art non-parametric minimum statistics algorithm. A speech intelligibility test, preference rating, and listening effort scaling were performed. Additionally, three objective quality measures for the signal, background, and overall distortions were applied. For a better comparison of all algorithms, particular attention was given to the usage of the similar Wiener-based gain rule. Study sample: The perceptual investigation was performed with fourteen hearing-impaired subjects. Results: The results revealed that the non-parametric algorithm and the auditory model-based algorithm did not affect speech intelligibility, whereas the speech-model-based algorithm slightly decreased intelligibility. In terms of subjective quality, both model-based algorithms perform better than the unprocessed condition and the reference in particular for highly non-stationary noise environments. Conclusion: Data support the hypothesis that model-based algorithms are promising for improving performance in non-stationary noise conditions.     

Advantages of Binaural Amplification to Acceptable Noise Level of Directional Hearing Aid Users

Objectives

The goal of the present study was to examine whether Acceptable Noise Levels (ANLs) would be lower (greater acceptance of noise) in binaural listening than in monaural listening condition and also whether meaningfulness of background speech noise would affect ANLs for directional microphone hearing aid users. In addition, any relationships between the individual binaural benefits on ANLs and the individuals'' demographic information were investigated.

Methods

Fourteen hearing aid users (mean age, 64 years) participated for experimental testing. For the ANL calculation, listeners'' most comfortable listening levels and background noise level were measured. Using Korean ANL material, ANLs of all participants were evaluated under monaural and binaural amplification with a counterbalanced order. The ANLs were also compared across five types of competing speech noises, consisting of 1- through 8-talker background speech maskers. Seven young normal-hearing listeners (mean age, 27 years) participated for the same measurements as a pilot testing.

Results

The results demonstrated that directional hearing aid users accepted more noise (lower ANLs) with binaural amplification than with monaural amplification, regardless of the type of competing speech. When the background speech noise became more meaningful, hearing-impaired listeners accepted less amount of noise (higher ANLs), revealing that ANL is dependent on the intelligibility of the competing speech. The individuals'' binaural advantages in ANLs were significantly greater for the listeners with longer experience of hearing aids, yet not related to their age or hearing thresholds.

Conclusion

Binaural directional microphone processing allowed hearing aid users to accept a greater amount of background noise, which may in turn improve listeners'' hearing aid success. Informational masking substantially influenced background noise acceptance. Given a significant association between ANLs and duration of hearing aid usage, ANL measurement can be useful for clinical counseling of binaural hearing aid candidates or unsuccessful users.     

Disturbance caused by varying propagation delay in non-occluding hearing aid fittings

The disturbance caused by various short propagation delays to the perception of external sounds and own voice for a non-occluding hearing aid was investigated. Ten normal-hearing and 10 mildly hearing-impaired individuals listened to external sounds and their own voice while wearing non-occluding devices providing 10dB of linear gain. Participants rated the disturbance caused by delays of 2, 4 and 10ms to music, running speech, and their own voices. The results indicated greater disturbance for the longest delay for both subject groups when judging own voice, with the ratings of the hearing-impaired participants being lowest. Normal-hearing participants also judged the 10-ms delay as more disturbing for the external sounds. Owing to the listening conditions with constant gain from 800Hz and above, the results apply directly only to this experiment. Disturbance ratings for all delays were low, which suggests that any of those tested would be acceptable for this application.     

Clinical Results of Hearing Aid with Noise-Level-Controlled Selective Amplification

We have developed a hearing aid which reduces the low-frequency energy of the input sound according to the input noise level and the spectrum of the environmental noise. The results of speech discrimination tests using speech in noise in 70 hearing-impaired subjects showed improvement in word discrimination scores in noise of over 15% for 50 of 53 subjects with sensorineural hearing loss. This group of hearing-impaired patients was subdivided into categories according to (a) audiogram type [flat, sloping (i.e. gradual high-frequency loss) and abruptly falling (steep high-frequency slope)]; (b) degree of hearing loss (less than or more than 50 dB average loss) and (c) etiology (familial deafness, presbyacusis). Results on 17 subjects with conductive or mixed hearing impairments showed no improvement, but expressed a preference for this system. The subject reported that the sound was more natural and quiet compared with the conventional AGC hearing aids.     

Rehabilitation of the hearing impaired adult in Denmark

An outline is given of the rehabilitation of the hearing impaired adult in Denmark. Emphasis is put on the comprehensiveness and the professionalism of the services provided.     

陡降型听力曲线者助听器选配效果观察

目的 为陡降型听力曲线的听障者选配助听器，使其能听清楚高频的声音。方法 听障者配戴助听器前和配戴普通线性放大助听器、多通道全数字电脑编程助听器后进行助听听阈、声源觉察率测试，并分别进行比较。结果 听障者配戴普通线性放大助听器与没有配戴助听器时助听效果没有明显差异；配戴多通道全数字电脑编程助听器和配戴普通线性放大助听器助听听阈在高频区有显著性差异，在对低频的正常耐受下大幅度补偿高频，从而助听听阈接近正常。结论 陡降型听力曲线听障者配戴多通道全数字电脑编程助听器，经过多次调整，对高频部分的听敏度有大幅度的提高。     

A Contemporary Review of Hearing Aids

A contemporary review of hearing aids is provided with a focus on current styles of amplification devices, the goals of a hearing aid fitting and the signal processing schemes that allow the clinician to meet these goals, and the need to couple outside devices to hearing aids. A variety of new features available on hearing aids that improve the listener's experience with amplification are described. Some future challenges in hearing aid design and hearing evaluation are presented.