Routine Audiometry Research Articles

Transient Evoked Otoacoustic Emissions Pattern as a Prognostic Indicator for Hearing Preservation in Acoustic Neuroma Surgery

To determine whether pre-operative transient otoacoustic emission (TEOAE) patterns are predictive of successful hearing preservation in acoustic neuroma surgery. Retrospective observational study. Tertiary referral medical center. A convenience sample was identified in whom pre-operative TEOAE data were available in patients undergoing acoustic neuroma surgery from 1993-2004. Ninety-three patients were identified who met this inclusion criterion. Subjects underwent attempted hearing preservation surgery via middle cranial fossa or retrosigmoid approaches. Routine audiometry, ABR, and TEOAE. Pre- and post-operative pure tone and speech results were categorized into hearing classes A, B, C, and D as described in the American Academy of Otolaryngology guidelines (1995). Hearing preservation was defined by maintenance of the pre-operative hearing class or downgrade to within one hearing class post-op. Pre-operative TEOAE results were divided into five frequency bands and described as positive in each band if there was a response above the noise floor with >50% reproducibility. Hearing was preserved in 51 patients (55%). Of these, 11 (22%) had positive TEOAE response in all five frequency bands measured (1, 1.5, 2, 3, 4 kHz), whereas 40 (78%) had TEOAE responses ranging from 0 to 4 frequency bands. 42 patients failed to preserve their hearing. Of these, only three (7%) had positive TEOAE in all five frequency bands, and 39 (93%) had TEOAE responses ranging from 0 to 4 frequency bands (p<0.05). Other variables of prognostic significance to hearing preservation in our series included smaller tumor size, tumor location within the IAC, better pre-operative hearing, and shorter latencies on ABR. Logistic regression was then used to compare the prognostic value of TEOAE against these variables. In our series, ABR latencies and 5 frequency band response on TEOAE showed the highest significant correlation to hearing preservation (p<0.05). A robust pre-operative TEOAE frequency band pattern may be used as a favorable prognostic indicator for potential hearing preservation in acoustic neuroma surgery. The prognostic value may be enhanced when combined with other prognostic factors such as tumor size, tumor location, pre-operative ABR and audiometric results.

Measures of auditory processing in aphasia: Behavioural and electrophysiological analysis

Background: Lesions resulting in aphasia frequently involve areas associated with auditory processing. Investigations using psychoacoustics and/or electrophysiology to examine the auditory processing abilities of aphasic as well as non-brain-damaged individuals have revealed the influence of several variables on findings, including age, type of stimuli, task difficulty/instructions, response modality, and lesion site/size. It is unclear whether both methods of testing are examining similar components of auditory processing and furthermore, if the variables identified as affecting findings for the two testing methodologies influence results in a similar manner. An electrophysiological approach to auditory processing may assist in the objective evaluation of patients who have difficulty consistently providing accurate responses. Aims: The purpose of this investigation was to explore behavioural and electrophysiological CAP abilities of several aphasic individuals using a set of divided attention tasks and to investigate whether electrophysiological results were congruent with those obtained from behavioural testing. Methods and Procedures: Participants were two females and five males, age range 33-73, all suffering left cerebrovascular accidents, resulting in aphasia. Experimental testing included: speech-language evaluation via administration of the Western Aphasia Battery and the Token Test ; hearing evaluation using routine pure-tone audiometry, speech audiometry, and middle ear measurements; behavioural central auditory processing assessment using Pitch Pattern Sequence and Dichotic Digits ; and electrophysiology testing, consisting of evaluation of late auditory evoked potentials (N100, P200, P300) with and without distraction using an oddball paradigm. Outcomes and Results: Results are presented individually for each patient. Overall, patients showed unique results relative to ear advantage pattern and congruence between electrophysiological and behavioural testing. One patient showed inconclusive findings due to a hearing loss; one patient showed no clear ear advantage pattern on either behavioural or electrophysiological testing; one patient showed no ear advantage on dichotic testing but showed a clear pattern on electrophysiology; and one patient showed incongruence in ear advantage pattern between electrophysiological and behavioural testing. Three patients showed congruent ear advantage patterns across both behavioural and electrophysiological testing; however, one showed a right ear advantage and two showed a left ear advantage. Conclusions: Based on these findings, it is evident that the direct and/or statistical relationship between behavioural CAP and electrophysiological findings requires more in-depth exploration. The testing of additional patients is imperative prior to making decisions regarding the utility and value of such a statistical approach. Thus, the use of these and other CAP measures bears additional investigation as clinical and experimental tools in evaluating auditory processing capabilities of the aphasic patient.

Carhart's notch: a finding in otitis media with effusion

Introduction: Carhart's notch (CN) is a false depression of bone conduction (BC) thresholds at 2–4 kHz initially described in cases of stapes fixation. This study was designed to estimate the incidence and assess the clinical significance of CN in cases of otitis media with effusion (OME) in children. Patients and methods: Clinical records of 50 patients of OME that showed CN were analysed, retrospectively. First 24 were identified as seen in outpatients and 26 were found out of 100 consecutive cases of OME. The criteria of CN were a minimum 10 dB depression in BC at any frequency 500–4000 Hz. Results: Fifty patients showed CN, with mean age of 8.8 years. All had myringotomies with or without insertion of grommets. The CN ranged from 10 to 20 dB in the majority and up to 30 dB in few cases. In 85 ears studied, the affected frequencies comprised of 2000 Hz in 80 (94%), 4000 Hz in 4 and 1000 Hz in one ear. Pre-operative tympanograms were of type B in 68 (80%), type C in 16 (18.8%) and type A in one ear. Middle ear fluid was thick glue in 57 (67%), serous in 5 (5.8%), and no fluid found in 23 (27%) cases. Oedematous, granular or polypoidal appearances of middle ear mucosa were noted in 57 (67%) of the ears. A normal mucosa was seen in 17 (20%), and no details were available in 11 (13%) ears. Post-operative audiograms showed improvements of BC thresholds in 72 (84.7%) of the ears. Conclusion: Our results show 26% incidence of CN in paediatric cases of OME, with evidence of thick fluid and abnormal middle ear mucosa in about two-thirds of cases. This suggests that CN may be of prognostic value for myringotomy outcomes. Statistically there is a significant correlation between presence of fluid on myringotomy and CN, and type of tympanogram and post-operative BC threshold improvement. There is no predictive value of CN in terms of character of the middle ear fluid. Studies with larger numbers may be required to determine this with more certainty. It can help clinically, however, in pre-operative assessment of these cases. It is our opinion that BC should be an essential part of routine audiometry in all cases of OME.

The effects of a connexin 26 mutation – 35delG – on oto-acoustic emissions and brainstem evoked potentials: homozygotes and carriers

The purpose of this study was to examine whether outer hair cells (OHCs), inner hair cells and the brainstem auditory pathway are impaired due to a mutation in a gap junction protein, connexin 26 (Cx26), 35delG. Fifty-six individuals, from a village with widespread consanguinity and profound, non-syndromic congenital deafness, due to 35delG mutation, were selected among relatives of deaf people. The individuals were either non-carriers ( n=20), heterozygous ( n=20) or homozygous ( n=16) for the mutation. Distortion product oto-acoustic emissions (DPOAEs) and auditory brainstem evoked potentials (ABEPs) in mutation non-carriers, in heterozygotes (carriers) and in subjects homozygous for the mutation were compared in addition to audiometric evaluation. Most deaf homozygotes had no DPOAEs, except some sporadic responses at 1000, 8000 and 10 000 Hz. This was also observed in audiometry which showed profound hearing loss in most cases. Two cases were unique: one had moderate to severe hearing loss and the other had severe to profound hearing loss. A significant difference was found between non-carriers and carriers of 35delG: non-carriers had larger DPOAE responses than heterozygotes at all frequencies. The prevalence of responses got lower with higher frequencies in both groups, but between 6000 and 10 000 Hz 50–70% of the carriers had no DPOAE responses, compared to 30–60% of non-carriers. In both groups responses diminished with age, but no significant interaction was found between age and the genetic group. ABEPs among homozygotes were variable: in most homozygotes ABEPs were absent or partial (waves III, V) with prolonged latencies, but two subjects had ABEPs within normal limits, in one ear. ABEPs were normal with no differences between carriers and non-carriers. We suggest that OHC function is affected by the 35delG mutation in Cx26. In addition, the hearing of carriers of this mutation may be impaired at very high frequencies (8000–10 000 Hz), which are not assessed in routine audiometry or ABEP testing.

Morphometric analysis of age-related changes in the human basilar membrane.

The histopathologic correlates of presbycusis suggest several categories, including degeneration of sensory cells, neurons, or the stria vascularis. Lack of clear-cut histopathologic changes in some cases has suggested an "indeterminate category"; however, several studies have suggested that a disorder of the basilar membrane (BM) may underlie indeterminate presbycusis. The objective of the present study was to quantify age-related changes in the human BM and correlate them with audiometric patterns. Under high-resolution light microscopy, BM thickness was calculated, and the number of tympanic mesothelial cells (TMCs) lining the BM was counted, at 4 cochlear locations in 92 temporal bones. The control group (n = 80) included subjects from 10 decades of age with normal hearing and/or histopathologic findings. The indeterminate group (n = 12) consisted of elderly patients (ages 64 to 91 years) with hearing loss and no apparent histopathologic changes. Age-related BM thickening was seen in both groups, but only in the most basal cochlear region. The BM thickness in the indeterminate group was not significantly different from that of age-matched controls. Counts of TMCs showed age-related decreases in all cochlear regions in both groups; however, TMC counts in the indeterminate group were not different from those of age-matched controls. The results suggest that BM histopathology is not a common cause of presbycusis. Although age-related BM thickening, seen in both groups, could contribute to hearing loss, the extreme basal region, to which the thickening was confined, is not tested in routine audiometry.

IFCN recommended standards for brain-stem auditory evoked potentials. Report of an IFCN committee

Electroencephalography and clinical Neurophysiology , 91 (1994) 12-17 © 1994 Elsevier Science Ireland Ltd. 0013-4694/94/$07.00 EEG 00007 IFCN recommended standards for brain-stem auditory evoked potentials. Report of an IFCN committee Marc R. Nuwer (Chairman) ( Los Angeles, CA, USA), Michael Aminoff (San Francisco, CA, USA), Douglas Goodin (San Francisco, CA, USA), Shigeaki Matsuoka ( Kitakyushu, Japan), Francois Maugui~re (Lyon, France), Arnold Starr ( Irvine, CA, USA) and Jean-Francois Vibert (Paris, France) (Received for publication: 14 February 1994) Introduction Brain-stem auditory and evoked potentials (BAEPs) have come into widespread use for assessment of the clinical state of the middle portion of the brain-stem and for assessment for hearing, particularly in the screening of infants at risk for hearing loss. They have found their way into routine hearing screening for infants. They have proven themselves as objective, re- producible, sensitive indicators of many types of brain- stem disturbances. The pathway tested by BAEPs include the acoustic conduction through the ear and the electrical transmis- sion from cochlea along th.e eighth nerve into lower pons, continuing rostrally through pons and up each lateral lemniscus into the midbrain. A series of 5 or more peaks are usually recorded from the ears and scalp vertex. The B A E P test can be easily recorded in most patients, including comatose or sedated patients in whom routine audiometry cannot be done. In fact, the best quality BAEP is often obtained with sleep or sedation. B A E P can be obtained in the presence of mild or moderate hearing impairment, but the main 5 peaks usually cannot be obtained in the presence of severe hearing impairment. Stimulation BAEPs are produced by a brief click stimulus. This is usually a square-wave electrical pulse 100/zsec Correspondence to: Marc R. Nuwer, M.D., Ph.D., Department of Clinical Neurophysiology, Reed Neurological Research Center, Uni- versity of California Los Angeles, 710 Westwood Plaza, Room 1194, Los Angeles, CA 90024 (USA). Fax: (310) 206-8461. SSDI 0013-4694(94)00045-M long. This brief pulse can move the earphone di- a p h r a g m either toward or away from the patient's ear. E a r p h o n e movement toward the ear is called an acous- tic condensation phase stimulus, whereas earphone movement away from the patient's ear is a rarefac- tion stimulus. Occasionally the two types of phase are concatenated, which is referred to as an alternating phase stimulus. The latter can be useful in reducing stimulus artifact seen with very loud stimulus intensi- ties. In clinical neurophysiology the rarefaction phase is usually chosen. Clicks are usually presented 10-70 t i m e s / s e e . At fast rates, data can be collected more quickly, but the peaks are more poorly defined. As a result, slower or intermediate rates are often chosen. The rates 11 and 3 1 / s e e are most commonly chosen. Rates are usually not exact factors divisible into 50 or 60 Hz, because such rates would predispose to line noise. Stimuli are often delivered at about 70 dB intensity. There are several different decibel scales in common clinical use. It is important to understand the differ- ence between these intensity scales. (1) Hearing level (dB NHL, dB HL, dB nHL): this scale refers to the n u m b e r of decibels of intensity c o m p a r e d to the threshold of hearing in a group of average normal subjects. Z e r o on this scale is defined as the threshold at which an average normal subject can just perceive the stimulus 50% of the time. (2) Sensory level (dB SL): this is the scale on which zero is defined as the point at which the individual patient can barely appreciate the stimulus. This may be very different from 0 dB HL. Patients with hearing loss may have their personal 0 dB SL found at very high intensities such as 70 dB NHL. (3) The physical definition (dB peSPL, peak equiva- lent sound pressure level): physical m e a s u r e m e n t of sound pressure levels use as the 0 dB reference level a

An Audiological Survey of Aircrew

AbstractA cross sectional survey of Royal Naval aircrew was performed to measure the prevalence of noise-induced hearing loss and assess its relationship to flying experience. The quality of routine audiometry undertaken at annual aircrew medical examinations was assessed and the requirement for further hearing conservation measures amongst Fleet Air Arm personnel considered.Analysis of the results indicated that 3.8% of aircrew had possible noise induced hearing loss, in 1.6% this was probably due to flying and none of these cases had less than 2,000 hours flying experience.Further surveys should concentrate on experienced aviators and on aircraft maintainers and handlers.As noise-induced hearing loss does not appear to be affecting aircrew with less than 10 years flying experience there is a potential saving in time and expense by ceasing to do routine audiometry on this group.

The validity of routine audiometry in industry : House, R.A.Occupational Health in Ontario, 1985, 6.2, 56–74

The validity of routine audiometry in industry : House, R.A.Occupational Health in Ontario, 1985, 6.2, 56–74

A three-frequency audiogram for use in industry.

Some form of audiometric screening forms part of any comprehensive hearing conservation programme, but because of the large numbers of workers exposed to noise, it is suggested that routine audiometry using an 8-frequency test preceded by history and examination makes undue demands on limited resources. It is proposed that a simple 3-frequency test without prior preparation of subjects is adequate for the purposes of industrial audiometry. Men whose hearing threshold was worse than 20 dB at 1, 2, or 4 kHz were considered to have failed the 3-frequency test and 150 such cases were randomly selected and subjected to a full 8-frequency audiogram. The results were then assessed for numerical accuracy and diagnostic reliability. The results of the 3-frequency test were marginally worse than the 8-frequency audiogram by 2.33 to 4.98 dB, and the comparison of the two tests as a diagnostic tool gave a concordance rate of 79%-80% (p = 0.00001) between the two physicians who examined the results and a level of interpersonal agreement of 87% for the 3-frequency test and 89% for the full audiogram. If audiometric screening is to be offered to the whole population at risk it should be simple, rapid, and accurate enough to detect hearing loss before disability develops so that those individuals may be counselled. It is suggested that the 3-frequency test fulfils this purpose, demonstrates the "reasonably practicable" approach of recent legislation, and does not unnecessarily divert resources from other key tasks in the practice of occupational medicine.

Mechanical explanation of the on-off effect (diphasic impedance change) in otospongiosis.

Impedancemetry gives important information in otospongiosis, both for relative compliance and impedance audiometry. The detection of the stapedius reflex is facilitated by recruitment in some audiometric types of otospongiosis and enables us to solve many of the masking problems which are particularly difficult in this disease due to the very important cross-hearing (or cross-over). Diphasic impedance changes (on-off effect) once detected must be systematically investigated since they allow us to detect otospongiosis early on. This sign is absolutely characteristic of the onset of a stapediovestibular involvement and is of primary interest in this disease because of its early appearance - before any classical audiometric change and any air-bone gap, i.e. before deafness. Diphasic impedance changes must thus be systematically investigated in case of so-called unilateral otospongiosis, in the audiometrically normal ear, and for the detection of otospongiosis in otospongiotic families. It is also helpful in confirming the otospongiotic origin of sensorineural losses before an air-bone gap appears. Our experience with routine stapedectomies and impedance audiometry measurements have led us to a purely mechanical explanation of the on-off effect, i.e. the response of an elastic system to a deformation with a different mechanism of the two inverse peaks, with a different mass and thus a different inertia. This mechanical explanation fits perfectly with anatomical findings. Everything occurs as if the evolutive stages of the onset of the stapediovestibular involvement were defined in impedancemetry, starting from the normal stapedius reflex, first by mixed forms, then by a pure on-off effect, finally by the disappearance of the stapedius reflex.

The role of electro-physiological tests in the diagnosis of non-organic hearing loss.

Today it is possible, by the use of newly developed tests, to diagnose cases of non-organic hearing loss with reasonable certainty. Having once decided that there may be non-organic elements, it is useful to supplement routine pure-tone and speech audiometry with a neurophysiological test like an ERA by means of which the auditory threshold can be established without the patients subjective judgement. A hearing loss which is apparent by routine pure-tone audiometry, but which is not evident after ERA is almost certainly non-organic, although confirmation of this state of affairs by other reliable tests is advisable. Measurement of the acoustic reflex thresholds and delayed speech feedback tests are both useful in this respect and rarely cause any confusion, except in some cases of true hearing loss in strongly recruiting ears.

An averaged electroencephalic audiometric sensitivity (AEA-S) procedure.

An averaged electronencephalic audiometric sensitivity (AEA-S) procedure is described, and its clinical utilization for gaining estimates of auditory sensitivity with children and adults who will not or cannot reliably respond during routine behavioral audiometry is demonstrated. Several precautions that clinicians who administer AEA procedures in the clinic should take are offered.

Precision audiometry.

Repeat within ear threshold variance can be considered to be made up of variables associated with the sensory system and those associated with the criterion adopted by the subject as to what is his threshold. Conventional audiometry is not able to separate out the effects of these different sources. Signal detection theory as applied to psychophysics would seem to offer a possible method of measuring the effects of the sensory and criterial variables separately. The variance in the measures of each of these terms for normal ears should be smaller than the variance of conventional threshold determinations. Hence the behaviour of normal ears can be more precisely specified and so departures from normality should be detected earlier than is at present possible. The problems which must be overcome if signal detection theory is to be successfully adapted for use in routine audiometry are discussed.

DIFFERENTIAL DIAGNOSIS OF PERCEPTIVE DEAFNESS POSSIBLE ONLY THROUGH A COMBINATION OF PURE TONE THRESHOLD TESTS

The author attempted to develop a new testing method to diagnose affected parts in perceptive deafness easily, quickly, and accurately in the course of daily clinic.The author found, as a result, that the diagnosis affected parts is possible by combining three test methods, namely the conventional audiometry (air and bone-conduction threshold test), a threshold test using an interrupted tone and a continuaus tone which are self-recorded, and a threshold difference test based on the masking level difference phenomenon of pure tones.This report describes the principles of diagnosis the scope of application of each test method.1. The conventional audiometry; This method should be considered to be threshold test designed to screen perceptive deafness out of various hearing disturbances. It should be noted that this routine audiometry, when employed for screening purposes, in subject to the following three restrictions: 1) the limit of the out-put level of bone conduction, 2) cases where the measurement of bone conduction threshold is impossible, and 3) cases where some types of perceptiv deafness fail to be screened.This problem can be solved by devising a test method which would enable screening of perceptive deafness without measuring bone conduction thresholds. As a method to suit this purpose, I have introduced - combination of an air conduction threshold test and an intensity difference limen using superimposed pip test developed by the author.2. Diagnosis by self-recording method; This is a new testing method developed by the author and his collaborators with a view to classify perceptive deafness into inner ear disturbances and retro-cochlear disturbances.In diagnosis, the author used the threshold difference between the threshold obtained by the interrupted tone (duration 200msec; rise and fall time 25msec ; repetition time 400 msec) ascending method and the threshold obtained through the continuous tone descending method (after exposing the ear to the level of 85dB on the hearing loss dial for thirty seconds). The case may be regarded as inner ear deafness, if this threshold difference is within 20dB, and as retro-cochlear deafness if the value is over 20dB.3. Diagnosis by Masking Level Difference Test (MLD-Test, EBIHARA'S) ; This method is employed to classify retrocochlear disturbances into those located in peripheral region and those located in central region of the tertiary neuron in auditory passway.This principle employs the difference in pure tone threshold caused when the sound images of a pure tone and of a noise are fused or separated artificially in binaural hearing. With the 1000cps, tone used for the MLD-Test, there is no distur. bance if this threshold difference is above 5dB, and if the value is under 4dB, the central region of the tertiary neurons in central auditory passway will be considered affected

Collapse of the ear canal during routine audiometry.

Collapse of the ear canal during routine audiometry.

A MOBILE UNIT FOR THE ASSESSMENT OF HEARING.

The report of the Wilson Committee on Noise has brought into prominence the subject of routine audiometry in industry. When measuring the hearing thresholds of employees subjected to high level noise, industrial concerns frequently find difficulty in providing a suitable acoustic environment. A simple, economic, mobile audiometric unit mounted on a two-wheeled trailer chassis is described. The design and construction details are given, together with the attenuation of the Unit in two different noise fields.

Collapse of the Ear Canal During Audiometry: A Further Report

The report by Ventry, Chaiklin, and Boyle of 2 cases of collapse of the external auditory canal during audiometry¹serves to emphasize a previously more or less neglected phenomenon and also to underline the importance of close professional interaction between otologist and audiologist. We began an investigation of the phenomenon of ear canal collapse during August, 1960. We were prompted to an investigation of this phenomenon more by observed and unexplained discrepancies between tuning fork observations and audiometric test results than by the inconsistencies in test results referred to by the previous writers. The possibility of ear canal collapse during audiometry was first suggested to us by a number of cases in which air-conduction bone-conduction gaps indicated by routine audiometry exceeded 20 db. but were not accompanied by negative Rinne responses when tuning forks were used. When a plastic stopple of the type used in preliminary hearing-aid evaluations was

Speech audiometry in persons with brain damage.

One hundred patients suffering from brain atrophy were subjected to pure tone, routine and special speech audiometry. No more than 35 met the criteria set for the study. Routine speech audiometry showed no great abnormality. By high-tone cut-offs, however, their scores were decidedly subnormal. Authors stress the importance of this finding for the evaluation of compensation cases.

Triplet Audiometry: An Analysis of Band Discrimination in Speech Reception

The great redundancy of normal speech under favourable conditions, e.g. in the way it is proffered to a patient in routine speech audiometry, opens the possibility of determining a person's discrimination skill in a discrete band of frequencies. By the use of fdtered speech consisting of components that cover only that discrete frequency band we can measure in the normal way the articulation score in that particular part of the pitch range.