Interaural Phase and the Release from Masking

In previous presentations to this congress we have reported an increase in intelligibility of isolated words at poor signal-to-noise ratios when the phase angle differences between the ears were adjusted to certain values. Question has arisen as to whether this phenomenon is one of a peculiar property of speech or one of that kind usually called release from masking. Therefore, a study was done to compare normal voiced speech with whispered speech at a signal-to-noise ratio of 0 dB and subject to various phase angle differences between the ears. Data are presented which suggest that the apparent release from masking may be due in part to properties of voice, but not entirely so.     

The Effects of White Noise on PB Score of Normal and Hearing-Impaired Listeners

There is increasing awareness among clinical audiologists of the inability of current speech discrimination tests to provide diagnostically significant data. In fact the most commonly used test of speech discrimination, the CID auditory test W–22 does not, according to Carhart [1965], separate persons with normal hearing from those with various types and degrees of hearing impairments. Although there has been discussion in the literature of mixing speech with noise to increase the diagnostic value of PB tests, very little data has been reported to date.

In the present study 10 persons with normal hearing, 10 persons with high-frequency hearing loss, and 10 persons with relatively flat hearing loss were used as experimental listeners. All listeners yielded PB score in quiet of 92% or better, i.e. a hearing impairment was not reflected in the PB score obtained in quiet.

CID auditory test W–22 words lists 1 and 2 were presented to these listeners at 40 dB SL or the sensation level necessary for PB Max. The words were presented in quiet and also in the presence of white noise. Three signal-to-noise (S/N) ratios were used; +8, 0, and –8 dB S/N. As the noise interference level increased the PB scores of all listeners deteriorated. The PB score of normal hearing listeners deteriorated approximately 52% from the quiet to the –8 dB S/N ratio, listeners with high-frequency hearing loss deteriorated approximately 57%, and listeners with flat hearing loss approximately 67%.

The PB scores of groups at the –8 dB S/N condition were significantly different at the 1.0% level of confidence. The data indicate certain directions for further research in order to arrive at a more useful speech discrimination test.     

Masking Level Difference: Another Tool for the Evaluation of Peripheral and Cortical Defects

Masking level difference (MLD) due to binaural unmasking was measured for speech signals (5-word meaningful sentences) masked by broad-band noise.

Tests were carried out in a group of patients with unilateral cerebral lesions of vascular origin and apparently normal pure-tone audiograms (CNS patients), in a control group (normally hearing young adults) and in 5 other groups of patients (conductive symmetrical hearing loss, conductive asymmetrical hearing loss, bilateral presbyacusis, unilateral sudden deafness, Menière's disease). Testing pattern implied three or more S/N ratios in the listening conditions, of S_mN_m, SΔtN_o and S_mN_u (noise correlated), and the speech signal intensity was 70 dB SPL re 20 μPa for the control group, whilst for the pathological cases, speech level intensities were established by means of alternate binaural loudness balance and simultaneous balancing median-plane localization procedures to assess subjective suprathreshold sound image localization at the midline. The results obtained in the control group and in the patients are discussed. With specific reference to the CNS patients, a statistically significant tendency was evident for the binaural condition to produce more MLD when the ear leading in time was ipsilateral to the normal hemisphere. The importance of this and of sensitized speech testing methods in CNS disorders is discussed on the basis of the results obtained in the CNS patients.     

The masking noise and its effect upon the human cortical evokes potential

Using both while noise and narrow-band noise as monaural stimuli, the human cortical evoked potential was recorded with different intensties of stimuli. With such stimuli, the N₁ peak of the response was prolonged in comparison to the response to the onset of a pure tone.

The effect of simultaneously stimulating one ear with a burst of pure tone and the other with noise such as might be used for masking the contralateral ear was also studied. In this situation the N₁ peak in response to the tone usually showed the amplitude that was to be expected if only the pure tone had been given without contralateral masking. The response to pure tones of various intensity levels in the presence of contralateral noise at a steady intensity was also measured.     

The Use of Masking in Evoked Response Audiometry

The authors studied the influence of white noise on acoustically evoked potetials. In evoked reponse audiometry (ERA), the rules of masking in common use in subjective audiometry must be applied. Bone conduction caused an evoked potential from the opposite ear even for 0-5 dB. To avoid cross-hearing, masking of the opposite ear is required. A noise level below 50 dB had only little effect on the evoked potentials of the contralateral ear

For contralateral noise levels exceeding 60 dB or monaural stimulation with white noise and tones, the threshold was displaced by the amount of the masking noise level, and the steepness of the input-output curve was increased. In 16 patients with inner ear deafness, this masking effect showed a different behaviour. Thus an additional diagnosis on inner ear deafness is possible in ERA     

Masking level difference: A measure of auditory processing capability

MLDs are evidence of the superiority of the binaural auditory system. Cochlear lesions do not necessarily impair the MLD and persons with cortical lesions are also able to produce normal MLDs. The evidence for intermediate level auditory pathway lesions is more equivocal. The MLD is not the only measure of binaural hearing and binaural hearing is itself only one measure of a number of complex auditory processes. In this experiment measures of MLDs, localization, temporal integration, central masking and difference limen for intensity were made on 11 persons with normal hearing. Correlational analyses including factor analysis indicated that the MLD is a fairly independent measure but that central masking, brief tone audiometry and difference limen for intensity represent related auditory tasks. The relationship of localization tasks in this picture is unclear.     

Masking Level Difference in Normal and Pathological Ears

The masking level difference (MLD) was studied in 9 normal subjects, in 15 patients with conductive hearing losses, in 9 subjects suffering from Menière's disease, and in 8 subjects with sensorineural hearing losses

Results showed that MLD's size not depend on the conductive impairement but it may be affected by the degree of the deafness both in Menière's disease and in sensorineural lesions     

新生儿耳聋多因素logistic回归分析

目的探讨新生儿耳聋的发病情况和听力筛查结果多因素分析。方法回顾性分析2002年6月～2004年12月我院出生的有条件进行TEOAE筛查的4666例新生儿并使用筛查登记表收集病例资料中的相关信息,对收集到的资料进行单因素与多因素logistic回归分析。结果新生儿TEOAE第一次筛查通过率80.5%,第二次筛查通过率91.5%,第三次筛查通过率53.3%。对3次筛查不通过的46人行ABR测试,其中14人双耳通过,16人双耳不通过,16人单耳不通过,新生儿耳聋患病率6.9‰(32/4666)。单因素分析发现多胎、外耳畸形、窒息病史、低体重、高胆红素血症、早产、阿氏评分<7分等因素与新生儿TEOAE筛查通过率相关。多因素logistic回归分析确定外耳畸形、窒息病史、低体重、高胆红素血症等为危险因素。结论外耳畸形、窒息病史、低体重、高胆红素血症等因素的是新生儿耳聋高危因素,应对新生儿围产期高危影响因素积极预防和治疗,减少耳聋发病率。     

The protective effect of adrenocorticotropic hormone treatment against noise-induced hearing loss

Objective

NIHL is a common problem, and steroids are the most effective treatment option. In this study, we aimed to evaluate the protective effects of the synthetic adrenocorticotropic hormone (ACTH) analogues, which induce endogenous steroid secretion, against noise-induced hearing loss (NIHL) and to compare their effectiveness with that of steroid treatment.

Auditory Threshold Impairment And Everyday Speech Reception

The effect of auditory threshold impairment on the reception, in quiet and in noise, of lists of sentences designed to represent everyday speech was investigated in war vetarans, the majority of whom had sensorineural hearing loss. It was found that reception of the sentences by the subjects could be predicted with reasonable accuracy by means of the articulation index, which proved to be a better predicted than the three-frequency average hearing level. The results indicate that everyday speech reception by listeners with impaired hearing is very largely determined by degree of threshold impairment and not by impairment of maximum speech discrimination, and that threshold impairment at frequencies above 2000 Hz has an adverse effect on speech reception in some noisy situations.     

The effect of a hearing aid noise reduction algorithm on the acquisition of novel speech contrasts

Audiologists are reluctant to prescribe digital hearing aids with active digital noise reduction (DNR) to pre-verbal children due to their potential for an adverse effect on the acquisition of language. The present study investigated the relation between DNR and language acquisition by modeling pre-verbal language acquisition using adult listeners presented with a non-native speech contrast. Two groups of normal-hearing, monolingual Anglophone subjects were trained over four testing sessions to discriminate novel, difficult to discriminate, non-native Hindi speech contrasts in continuous noise, where one group listened to both speech items and noise processed with DNR, and where the other group listened to unprocessed speech in noise. Results did not reveal a significant difference in performance between groups across testing sessions. A significant learning effect was noted for both groups between the first and second testing sessions only. Overall, DNR does not appear to enhance or impair the acquisition of novel speech contrasts by adult listeners.     

氨甲喋呤在KLH诱导的豚鼠内耳炎症模型中的作用

目的 探讨使用免疫抑制methotrexate(MTX)直接进行内耳灌注是否可以减轻或抑制免疫反应介导的内耳炎症。方法 选健康Hartley豚鼠35只,随机分为4组,以钥孔戚血蓝素(Keyhole limpet hemocyanin,KLH)作抗原(0.5mg/0.5ml)经皮下注射进行基础免疫。手术显微镜下进行乳突根治术,暴露耳蜗,选蜗底鼓阶做微孔(直径≤30μm),灌注KLH制作内耳迷路炎模型。实验耳灌注KLH,或MTX,或二者之混合物,对照耳灌注PBS。随机选11只豚鼠进行血清抗KLH抗体的ELISA检测。借助听脑干反应(auditory brainstem response,ABR)和内耳的组织形态学改变观察MTX肌肉注射与内耳灌注对KLH诱导的豚鼠内耳炎症模型的听力保护作用。结果 ABR及内耳组织学均支持KLH诱导的豚鼠内耳迷路炎模型;血清抗KLH抗体ELISA检测显示KLH免疫后血清相应的抗体升高;肌肉注射或内耳局部灌注MTX,均不能阻止或减轻KLH诱导的豚鼠内耳炎症。结论 本研究不支持免疫抑制剂MTX可减轻或阻止豚鼠内耳炎症。     

The psychological and social consequences of single-sided deafness in adulthood

Objectives: This study examined the subjective psychological and social effects of highly asymmetric hearing loss (single-sided deafness [SSD]) in adults. Design: Three group interviews were conducted using the critical incident technique and analysed using an inductive thematic analysis. Study sample: Eight adults with a clinical diagnosis of a moderately severe hearing loss or greater in one ear and normal or near-normal hearing in the other ear. Results: A range of functional hearing difficulties associated with SSD including impaired speech in background noise and reduced spatial awareness were reported to affect social and psychological well-being. Social consequences of SSD resulted from activity limitations and participation restrictions including withdrawal from and within situations. Participants reported psychological effects including worrying about losing the hearing in their other ear, embarrassment related to the social stigma attached to hearing loss and reduced confidence and belief in their abilities to participate. Conclusions: Single-sided deafness can be associated with many negative consequences. Counselling may help overcome the psychological consequences of hearing loss regardless of whether technological support such as a hearing aid is prescribed. The audiological management of these individuals should support the development of listening strategies and set appropriate expectations for participation in everyday listening situations.     

Aided cortical auditory evoked potentials in response to changes in hearing aid gain

Abstract

Objective: There is interest in using cortical auditory evoked potentials (CAEPs) to evaluate hearing aid fittings and experience-related plasticity associated with amplification; however, little is known about hearing aid signal processing effects on these responses. The purpose of this study was to determine the effect of clinically relevant hearing aid gain settings, and the resulting in-the-canal signal-to-noise ratios (SNRs), on the latency and amplitude of P1, N1, and P2 waves. Design & Sample: Evoked potentials and in-the-canal acoustic measures were recorded in nine normal-hearing adults in unaided and aided conditions. In the aided condition, a 40-dB signal was delivered to a hearing aid programmed to provide four levels of gain (0, 10, 20, and 30 dB). As a control, unaided stimulus levels were matched to aided condition outputs (i.e. 40, 50, 60, and 70 dB) for comparison purposes. Results: When signal levels are defined in terms of output level, aided CAEPs were surprisingly smaller and delayed relative to unaided CAEPs, probably resulting from increases to noise levels caused by the hearing aid. Discussion: These results reinforce the notion that hearing aids modify stimulus characteristics such as SNR, which in turn affects the CAEP in a way that does not reliably reflect hearing aid gain.

Sumario

Objetivo: Existe interés en el uso de los potenciales evocados auditivos corticales (CAEP) para evaluar la adaptación de auxiliares auditivos y la plasticidad relacionada con la experiencia, asociada a la amplificación; no obstante, se sabe poco sobre los efectos del procesamiento de las señales de los auxiliares auditivos sobre esas respuestas. El propósito de esta investigación fue determinar el efecto clínicamente relevante de los ajustes de ganancia de auxiliares auditivos y las relaciones señal/ruido (SNR) resultantes en el conducto auditivo, sobre la latencia y la amplitud de las ondas P1, N1 y P2. Diseño y muestra: Se registraron en nueve adultos normoyentes los potenciales evocados y las mediciones acústicas en el conducto auditivo externo en condiciones de amplificación o sin ella. En la primera condicion, se envió una señal de 40-dB al auxiliar auditivo programado para proveer cuatro niveles de ganancia (0, 10, 20 y 30 dB). Como control, se parearon niveles de estímulos sin amplificación con las salidas de los estímulos amplificados (p.ej., 40, 50, 60 y 70 dB) para efectos comparativos. Resultados: Cuando los niveles de la señal están definidos en términos de niveles de salida, los CAEP con amplificación fueron sorprendentemente menores y tardíos que los CAEP sin amplificación, probablemente como resultado de los incrementos en los niveles de ruido, causados por el auxiliar auditivo. Discusion: Estos resultados refuerzan la idea de que los auxiliares auditivos modifican las características de los estímulos como la SNR, la cual a su vez afecta los CAEP en una forma que no refleja confiablemente la ganancia del auxiliar auditivo.     

两种不同长度的人工耳蜗电极对不同频率残余听力的影响

目的探讨植入两种不同长度的人工耳蜗电极对患者不同频率残余听力的影响。方法以中耳、内耳无明显异常的15例单侧植入Nucleus 24型人工耳蜗(A组,电极长度17mm)患儿与15例单侧植入Medel C40+15型(B组,电极长度29.2mm)人工耳蜗患儿为对象,两组对象于手术前后分别进行听性稳态反应(ASSR)测试,比较不同长度的人工耳蜗电极植入对不同频率听力的影响。结果①人工耳蜗植入后一月开机经耳蜗电刺激后,有51.67%患者植入耳保留残余听力;②手术前0.5、1、2、4kHz ASSR反应阈A组分别为98.93±6.28、107.80±8.16、104.07±8.83及104.73±5.93dB HL,B组分别为99.67±4.20、110.87±8.17、109.93±7.51及106.93±4.35dB HL;手术后一月上述各频率ASSR反应阈A组分别为101.60±4.64、112.60±6.11、106.13±5.19及106.60±6.25dB HL;B组分别为101.40±3.96、116.33±2.58、113.13±3.84及108.46±3.76dB HL;③术后B组0.5、1kHz的残余听力损伤明显,2、4kHz处残余听力损伤程度与A组差异无统计学意义;④A组术后残余听力损失以1kHz最显著,B组术后残余听力损失以500Hz最显著。结论人工耳蜗植入及耳蜗电极电刺激对植入耳的残余听力并非完全破坏,电极长短对不同频率残余听力会造成不同程度的损害,植入电极越长,植入耳蜗的部位越深,对低频残余听力损伤越明显。     

The effect of non-native and non-regional speech testing on a multi-lingual population

Objective: This study was conducted to evaluate the speech perception of Malaysian Chinese adults using the Taiwanese Mandarin HINT (MHINT-T) and the Malay HINT (MyHINT). Design: The MHINT-T and the MyHINT were presented in quiet and noise (front, right and left) conditions under headphones. Results for the two tests were compared with each other and with the norms for each test. Study sample: Malaysian Chinese native speakers of Mandarin (N?=?58), 18–31 years of age with normal hearing. Results: On average, subjects demonstrated poorer speech perception ability than the normative samples for these tests. Repeated measures ANOVA showed that speech reception thresholds (SRTs) were slightly poorer on the MHINT-T than on the MyHINT for all test conditions. However, normalized SRTs were poorer by 0.6 standard deviations for MyHINT as compared with MHINT-T. Conclusions: MyHINT and MHINT-T can be used as norm-referenced speech perception measures for Mandarin-speaking Chinese in Malaysia.     

The effect of EMG magnitude on the masseter vestibular evoked myogenic potential (mVEMP)

IntroductionThe masseter vestibular evoked myogenic potential (mVEMP) is a bilaterally generated, electromyographically (EMG)-mediated response innervated by the trigeminal nerve. The purpose of the present investigation was to 1) determine whether subjects could accurately achieve and maintain a range of EMG target levels, 2) to examine the effects of varied EMG levels on the latencies and amplitudes of the mVEMP, and 3) to investigate the degree of side-to-side asymmetry and any effects of EMG activation.MethodsSubjects were nine neurologically and otologically normal young adults. A high-intensity tone burst was presented monaurally while subjects were seated upright and asked to match a range of EMG target levels by clenching their teeth. Recordings were made from the ipsilateral and contralateral masseter muscles referenced to the ear being monaurally stimulated.ResultsWe found that the tonic EMG target had no effect on mVEMP latency. Additionally, although mVEMP amplitudes “scaled” to the EMG target, there was a tendency for the subjects’ EMG level to “undershoot” the EMG target levels greater than 50 μV. While some individuals did generate differences in EMG activation between sides, there were no significant differences on average EMG activation between sides. Further, while average corrected amplitude asymmetry was similar across EMG targets, some individuals demonstrated large, corrected amplitude asymmetry ratios.ConclusionsThe results of this investigation suggest that, as with cVEMP recordings, the underlying EMG activation may vary between subjects and could impact mVEMP amplitudes, yet could be mitigated by amplitude correction techniques. Further it is important to be aware that even young normal subjects have difficulty maintaining large, tonic EMG activity during the mVEMP recording.     

代谢综合征患者听皮层区磁共振氢质子波谱分析

目的：探讨磁共振氢质子波谱（1 H magnetic resonance spectroscopy ,1 H －MRS）技术对代谢综合征患者听皮层神经细胞损伤的早期预警作用。方法随机抽取确诊的代谢综合征患者142例,根据纯音听阈将其分为代谢综合征并双侧耳聋组（23例）、代谢综合征并单侧耳聋组（20例）、单纯代谢综合征组（99例）,以健康志愿者15例为正常对照组,各组行双侧颞横回听皮层1 H －MRS检测,根据听皮层神经代谢产物峰下面积计算 N －乙酰天门冬氨酸／肌酸（NAA／Cr）、胆碱／肌酸（Cho／Cr）、肌醇／肌酸（mI／Cr）、N －乙酰天门冬氨酸／胆碱（NAA／Cho）值,比较各组间上述各项指标的差异;根据ROC曲线下面积判定上述各指标诊断早期代谢综合征并感音神经性听力损失的敏感性及特异性。结果与正常对照组对应侧相比,单纯代谢综合征组听皮层神经代谢产物NAA／Cho降低,Cho／Cr升高（P＜0．05）;代谢综合征合并双侧耳聋组与单纯代谢综合征组比较 NAA／Cho 降低,Cho／Cr 升高（P＜0．05）;代谢综合征合并单侧耳聋组患侧和健侧NAA／Cho均下降,且患侧NAA／Cho较健侧降低更显著（P＜0．05）。代谢综合征患者颞横回NAA／Cho的ROC曲线下面积为81％时准确性较高,且当NAA／Cho为1．82时可以作为总体代谢综合征患者与代谢综合征合并感音神经性聋的分界指标,其余神经代谢产物ROC 曲线下面积均＜50％。结论听皮层磁共振氢质子波谱分析听皮层神经代谢产物NAA／Cho 有可能作为判定代谢综合征人群发生感音神经性聋的早期预警指标。     

The effect of longitudinal noise exposure on behavioral audiograms and transient-evoked otoacoustic emissions

The ear vulnerability of a group of combat soldiers was tested. The study initially included 84 soldiers and lasted two years. The soldiers were exposed to the noise of small-arms fire. Measurements included transient-evoked otoacoustic emissions (TEOAE) and pure-tone audiometry. Measurements, initially performed prior to the soldiers’ basic training, were repeated several times during the study. In general, TEOAE levels (E_m) decreased over time. About 57% of the ears developed a slight hearing loss (SHL) after two years of noise exposure. We define SHL as a threshold shift of 10 dB or greater, in at least at one of the audiometric frequencies 1000, 2000, 3000, 4000, or 6000 Hz. About 63% of the tested ears that had medium TEOAE level (1<E_m<8 dB SPL) prior to the noise exposure, developed SHL. On the other hand, among the ears whose E_m were either very low (E_m≤1 dB SPL) or very high (E_m≥8 dB SPL), less than 30% developed SHL. We suggest a prediction for ear vulnerability on the basis of E_m prior to noise exposure.     

The development and evaluation of the Finnish digit triplet test

Objectives: The aim of the study was to develop a reliable and easily accessible screening test for primary detection of hearing impairment.

Methods: Digits 0–9 were used to form quasirandom digit triplets. First, digit specific intelligibility functions and speech recognition thresholds (SRTs) were determined. To homogenize the test material digits with steep intelligibility function slopes were chosen and level correction up to ±2?dB were applied to the digits as needed. Evaluation measurements were performed to check for systematic differences in intelligibility between the test lists and to obtain normative reference function for normal-hearing listeners.

Results: The mean SRT and the final slope of the test lists were ?10.8?±?0.1?dB signal-to-noise ratio (SNR) and 21.7?±?1.8%/dB, respectively (measurements at constant level; inter-list variability). The mean SRT and slope of the test subjects were ?10.8?±?0.5?dB SNR and 23.4?±?5.2%/dB (measurements at constant level; inter-subject variability). The mean SRT for normal-hearing young adults for a single adaptive measurement is ?9.8?±?0.9?dB SNR.

Conclusion: The Finnish digit triplet test is the first self-screening hearing test in the Finnish language. It was developed according to current standards, and it provides reliable and internationally comparable speech intelligibility measurements.