Comparative study between the normally hearing child and the hard of hearing child, by acoustic impedance measurements of the ear

In the first part, the author makes a comparative study of the tympanometric results obtained from the normally hearing child and the hard of hearing child. The frequency of serous otitis media is statistically higher in the deaf child. The author compares such results of tympanometry as obtained from the child, considers the contribution of this technique to the field of pediatric audiology and suggests a classification of tympanograms in terms of the probe-tone frequency of the impedancemeter. The second part concerns the acoustico-facial reflex. This study compares the recording of the stapedius reflex obtained by pure tone and Narrow-Band noise acoustic stimulation, thanks to Madsen electro-acoustic bridge, in two groups of children, the one consisting of normal hearing children and the other of children suffering from severe perception hearing loss. The study of the stapedius reflex threshold makes it possible to analyse the dynamics of the field of perception in both groups. After an analysis of the results, the author outlines the importance attributable to the study of the stapedius reflex in the child as a means of objectively examining the auditive function and a means of differential diagnosis in cases of sensorineural impairment of the hearing function.     

The influence of sound stimulus parameters on the acoustic reflex waveform

Summary The transient increase in admittance seen at the beginning of the acoustic reflex response in man was investigated with a view to reaching a better understanding of its possible mechanisms. The sound stimulus intensity, its duration and its off-time were varied to investigate their effects on the morphology of the admittance waveform. The results found suggest that the transient increase may not be due to a temporary partial decoupling of the ossicular chain during the initial stages of stapedial contraction, but rather that it may be caused by a slight improvement in the coupling between the middle ear components.Offprint requests to: S. Freeman     

The effects of childhood otitis media on the acoustic reflex threshold at age 15

Previous research has found that childhood otitis media leads to elevated adulthood acoustic reflex thresholds because of worsened audiometric thresholds in the stimulation ear, and abnormality of the tympanic membrane in the ear from which acoustic reflexes were measured. To confirm and expand this finding, our research utilized longitudinal data from 631 general-population-sampled children assessed between ages 5 and 15. Otitis media was assessed to age 9, audiometric thresholds were measured at age 11, and otoscopy and acoustic reflex thresholds testing were performed at age 15. Our findings support the earlier research, in that acoustic reflex threshold was higher in those with the worst experience of childhood otitis media. However, this was directly mediated not by audiometric threshold in the ear to which the stimulus was delivered, but by the amount of tympanic membrane abnormality in both the stimulus and probe ears. This appeared to have an effect independent of audiometric threshold. Furthermore, only those who suffered the worst, persistent, binaural childhood otitis media showed raised acoustic reflex thresholds.     

Voluntary increase of acoustic middle ear impedances with simultaneous sound attenuation associated with mild hyperacusis (VIMH)

Background: Acoustic impedances, as measured with tympanometers, change with the pressure in the middle ears, or reflexively as a response to a range of stimuli. A few persons are able to influence their acoustic impedances voluntarily.

Aims/objectives: To describe this phenomenon and its clinical consequences.

Material and methods: Presentation of five case reports with measurements of the acoustic impedances, hearing thresholds, and otoacoustic emissions (TEOAE) in the relaxed state and while the change in acoustic impedance was invoked.

Results: All five subjects were able to voluntarily increase the acoustic impedance of their ears for short periods of time. While the change was active, TEOAE levels decreased by 0.8–9.7?dB and a mild transient conductive hearing loss in the low frequencies occurred. Four out of the five subjects reported a mild hyperacusis when the voluntary change was not invoked and showed unusual features in their acoustically evoked reflex.

Conclusions and significance: Subjects who can control their acoustic impedances voluntarily seem to have an increased prevalence of mild hyperacusis. Our results suggest interference of the voluntary control with the acoustic stapes reflex as a mechanism and we propose to name this phenomenon ‘Voluntary Impedance increase with Mild Hyperacusis’, or VIMH.     

Stapedius reflexes to electrical stimulation in the rabbit for the assessment of hearing

Summary The possibility of using electrically induced stapedius reflexes as a means of objective hearing evaluation was investigated in the rabbit as an animal model. The contralateral stapedius reflex to acoustic and electrical stimulation was measured in anesthetized rabbits. For electrical stimulation, the middle ear was opened surgically and stimulation was applied by a monopolar electrode placed at or into the round window. Contraction of the middle ear muscle was monitored by digital sampling and averaging of the impedance changes in the contralateral ear. Acoustically evoked reflexes were recorded within expected limits despite anesthesia. The level of the electrical stimulus was raised until mass reflexes of the neck muscles were observed. A contralateral stapedius reflex to electrical stimulation could not be demonstrated. In our experiment, monopolar electrical stimulation at the round window could not elicit contralateral stapedius reflexes.     

Concomitant changes in the acoustic impedance and the cochlear microphonic potentials during twitch contractions of the middle ear muscles in cats

Summary The effect of twitch contractions of the middle ear muscles in cats on sound transmission through the middle ear (as measured by the cochlear microphonic potential of the inner ear) was compared with the simultaneous changes in the acoustic input impedance of the middle ear at the same frequency. It was found that decreases in impedance were related to an increase in the amplitude of the cochlear microphonics and vice versa. This may imply that decreases in impedance measured during the initial phase of the acoustic reflex in man are true decreases and are not due to transient decoupling of the ossicular chain at any point.Supported in part by a grant from the Robert Szold Institute for Applied Sciences. Part of a Ph.D. thesis submitted by S. Freeman to the Senate of the Hebrew University, Jerusalem     

Middle ear influence on otoacoustic emissions. I: noninvasive investigation of the human transmission apparatus and comparison with model results

Evoked otoacoustic emissions (EOAEs) are generated within the cochlea in response to external sounds, and they can be acoustically detected in the external auditory meatus after backward propagation through the middle ear. In addition to being used to probe the cochlear mechanisms, they are expected to be sensitive to minute changes in middle ear impedance. Systematic measurements of the changes in the vectorial components of EOAEs were carried out after various manipulations of the human middle ear in order to characterize the influence of stiffness and inertia of the stapes and tympanic-membrane systems. For this purpose, stapedius muscle contractions were elicited by high-level contralateral sound, controlled changes in middle ear pressure (range ±100 daPa) were produced and the tympanic membrane was loaded with water droplets. A computer model of the middle ear network was implemented using a standard lumped-element electric analog of the middle ear (Zwislocki’s model). Forward and backward transmission changes were simulated and model predictions were compared to experimental data. Apart from the case of positive middle ear pressures, a close qualitative correspondence was found between model and real-ear results. Each of the effects was characterized by a unique pattern of phase and magnitude changes as a function of frequency, in relation to the mechanical characteristics of the involved subsystem (i.e. stapes stiffness, tympanic-membrane stiffness or mass) and its resonance properties. Owing to their high sensitivity, EOAEs could be helpful for an accurate individual multifrequency analysis of middle ear impedance by comparisons under rest and test conditions.     

Management of acoustic neuroma in the only hearing ear

Patients with acoustic neuroma in their only hearing ear are not frequently seen in clinical practice. Managing this group of patients is a challenge to both the patient and surgeon. In this study we report on five cases of acoustic neuroma in an only hearing ear. Our decision for conservative management of those patients with regular follow-up using auditory brain stem response and magnetic resonance imaging is discussed. Other management options currently available are reviewed as well.     

Comparison between hearing threshold measurements made with and without the aid of an ear speculum

The hearing threshold levels of a small group of shipyard workers having differing degrees of hearing impairment were measured five times using the following audiometric techniques: fixed-tone Békésy audiometry with MX 41/AR cushions, fixed-tone Békésy audiometry with an ear speculum, and sweep-frequency Békésy audiometry with an ear speculum. From these data the mean standard deviations of the hearing threshold levels for the frequencies 0.5, 1, 2, 3, 4, 5, 6, 7 and 8 kHz were calculated, thus giving a measure of the accuracy of each method. The hearing threshold levels obtained by the three methods are compared, and the merits of data handling, expressing hearing threshold levels in pascals rather than decibels, are also discussed.     

Wideband acoustic immittance in children with Down syndrome: prediction of middle-ear dysfunction,conductive hearing loss and patent PE tubes

Objective: The purpose of this study was to evaluate pressurised wideband acoustic immittance (WAI) tests in children with Down syndrome (DS) and in typically developing children (TD) for prediction of conductive hearing loss (CHL) and patency of pressure equalising tubes (PETs). Design: Audiologic diagnosis was determined by audiometry in combination with distortion-product otoacoustic emissions, 0.226?kHz tympanometry and otoscopy. WAI results were compared for ears within diagnostic categories (Normal, CHL and PET) and between groups (TD and DS). Study sample: Children with DS (n?=?40; mean age 6.4 years), and TD children (n?=?48; mean age 5.1 years) were included. Results: Wideband absorbance was significantly lower at 1–4?kHz in ears with CHL compared to NH for both TD and DS groups. In ears with patent PETs, wideband absorbance and group delay (GD) were larger than in ears without PETs between 0.25 and 1.5?kHz. Wideband absorbance tests were performed similarly for prediction of CHL and patent PETs in TD and DS groups. Conclusions: Wideband absorbance and GD revealed specific patterns in both TD children and those with DS that can assist in detection of the presence of significant CHL, assess the patency of PETs, and provide frequency-specific information in the audiometric range.     

The definition of acoustic impedance and its application to the human hearing organ

Acoustic impedance measurement at the point of entry into the external auditory meatus provides a rapid means to detect malfunctions of the middle ear in the region of the tympanic membrane, without having recourse to perforating the tympanic membrane. In this article we define acoustic impedance and provide a brief reminder of its physical properties. In the last part, we review the possibilities offered by measurement of the impedance to acoustic stimuli, not only for clinical diagnosis, but also in the understanding ot the physical phenomena occurring within the hearing organ.     

The importance of acoustic impedance measurements in middle ear pathology during acute viral respiratory illness in the first year of life

The very high incidence of ME pathology in epidemic bronchiolitis prompted the systematic use of impedance measurement tests in a study of the otitic process. Data were assembled of 44 children admitted to the Paediatric Clinic with acute viral respiratory infection (in the last years). On account of the high incidence (97%), the precocity of occurrence (1–12 months), the slow rehabilitation and the frequency of relapses, the ME pathology in these children indicates the importance of a correct approach to the problems of relapsing otitis in infants. Patients were treated with aerosol therapy (mucolytic substance), nasal drops (with vasoconstrictors), and only in very serious cases with antibiotics. For the latter, cortisonic therapy is inadvisable, while it is absolutely necessary to follow up with periodic controls until the tympanogram becomes normal. The impedance findings (prevalent type B curves, with inability to evoke the stapedius reflex, over periods of several months) and their resolution in type AC or C curves led us to consider not only the organic problem, but also the functional hearing problem during the first year of life, and the possible long-term repercussion.     

中耳肌肉生理及病理

中耳肌肉是耳部“降噪系统”中最为关键的部分,其在持续监测声学输入和动态调节听觉灵敏度方面发挥着重要的保护作用。当中耳肌肉收缩时, 它们将镫骨推入卵圆窗, 并增加内耳膜迷路内液体的压力。如果中耳肌肉失去调节内耳压力的能力, 如强直、痉挛或肌张力障碍, 产生的异常压力将对内耳压力产生影响, 并导致许多问题, 如耳鸣、梅尼埃病和感音神经性听力损失等。综述中耳肌肉的生理构造及各自所起的作用,讨论中耳肌肉功能紊乱与耳部疾病的联系。     

Intracochlear acoustic pressure measurements: transfer functions of the middle ear and cochlear mechanics

Direct intracochlear acoustic pressure recordings (from 20 to 20,000 Hz) are used to measure the middle-ear transfer functions (forward and reverse) and to better understand the cochlear mechanics in the guinea pig. In the forward direction, the middle-ear transfer function is strongly dependent on the frequency and presents a maximum of +30 dB at 1,000 Hz (bulla open). In the reverse direction, the middle-ear transfer function looks like an ideal reverse middle-ear pressure transformer with -35 dB gain and 0 degrees phase lag from 20 to 8,000 Hz (bulla open, closed ear canal). Passive cochlear mechanics is studied with the help of intracochlear pressure measurements and differential cochlear microphonic potential recordings in the different turns.     

重症监护病房与母婴同室新生儿听力筛查比较

目的 探讨新生儿重症监护病房患儿听力筛查情况并与母婴同室新生儿听力筛查情况进行比较。方法 对927例新生儿重症监护病房患儿和16353例母婴同室新生儿采用瞬态诱发耳声发射进行初筛和复筛,并对筛查阳性者进行诊断性听力学检测。结果 927例新生儿重症监护病房患儿中,通过筛查发现感音神经性听力障碍28例,其中高胆红素血症11例,极低体重儿9例,缺血缺氧性脑病6例,脑膜炎2例,检出率为3.02%（28/927）;母婴同室听力筛查新生儿16353例中,发现感音神经性听力障碍50例,检出率为0.31%（50/16353）,其中有宫内感染史23例,高胆红素血症12例,有耳聋家族史10例,脑膜炎病史3例,母亲孕期耳毒性药物使用史2例,二者差异有统计学意义（P＜0.05）。结论 新生儿重症监护病房患儿感音神经性听力障碍的检出率明显高于母婴同室新生儿;高胆红素血症、极低体重儿和缺氧缺血性脑病是新生儿重症监护病房患儿感音神经性听力障碍发生的主要高危因素;宫内感染、高胆红素血症及耳聋家族史是母婴同室新生儿感音神经性听力障碍发生的主要高危因素,应该强化对这部分新生儿听力筛查和干预工作。     

The relationship between self‐reported difficulty withT hearing in the worse ear and the better ear

Objectives: To investigate the relationship of self‐reported hearing difficulty with hearing in the worse ear and the better ear at 1 and 4 kHz. Design: Receiver‐operating characteristic (ROC) curve analysis in community‐residing population. Settings: The Settsu City Health Center (Osaka, Japan). Participants: A total of 919 consecutive participants who were provided health check‐ups. Main outcomes measures: Comparison is based on the measurement of the area under the curve (AUC) of ROC. Results: At 1 kHz, the area under the curve (AUC) of the worse ear (0.625 ± 0.021) was significantly larger than that of the better ear (0.570 ± 0.021) (P < 0.01). At 4 kHz, the AUC of the worse ear (0.665 ± 0.019) was significantly larger than that of the better ear (0.622 ± 0.020) (P < 0.01). Excluding the subjects with noise exposure, tinnitus and ear disease, at both frequencies, the AUC of the worse ear was not significantly larger than that of the better ear at both 1 and 4 kHz. Hearing in the worse ear was significantly more related to self‐reported hearing difficulty than in the better ear without excluding those with noise exposure, tinnitus and ear disease. Conclusions: ROC curve analysis would provide a method to help us judge the difference between the worse hearing ear and the better hearing ear on the subject of hearing loss.