Audiogram Shape Research Articles

Pure-tone and speech audiometry in patients with Menière's disease.

The aim of this study was to reinvestigate many of the claims in the literature about hearing loss in patients with Menière's disease. We carried this out on a well-defined group of patients under well-controlled circumstances. Thus, we were able to find support for some claims and none for many others. As part of a diagnostic protocol, pure-tone and speech audiometry was performed on 111 patients with Menière's disease according to the 'Definition Menière Groningen'. This was a prospective clinical cohort study. Affected ears of patients suffering from Menière's disease show reduced hearing, both in pure-tone and in speech audiometry. A classification method was devised to determine audiogram shape in an objective manner. The results of this method indicate that affected ears more frequently show 'low' or 'low + high' hearing losses (P = 0.006). The shape of the hearing loss does not depend on the duration of the affection of the disease. In combination with the fact that the average hearing loss does not correlate with the duration of the disease, this leads to the conclusion that, if a classification of the hearing loss in Menière's disease is possible, such a classification cannot be connected to the duration. This conclusion is further supported by the fact that no relationship is found between the duration of the disease and the classification of the hearing loss over the 3 months before hospital admission, as given by the patients in a questionnaire. A relationship between the (objective) audiometric data and the (subjective) classification of the hearing loss by the patient seems to be present, but is not very strong. Correlations between pure-tone and speech audiometry are present as in non-Menière ears (r = 0.899, P < 0.001), and no indications are found of reduced speech discrimination relative to the expectation based on pure-tone loss. The audiogram shape does not appear to play any additional role in speech discrimination (in addition to the influence of the average pure-tone loss).

A study of the effects of cochlear loss on the auditory brainstem response (ABR) specificity and false positive rate in retrocochlear assessment.

The auditory brainstem response (ABR) test is widely used as a screen for retrocochlear dysfunction in individuals suffering idiopathic auditory and vestibular disturbance. Although its sensitivity for lesions of the lower brainstem is well established, hearing loss is known to have significant effects upon the test's specificity and false positive rate. This study analysed the effects of aspects of cochlear hearing loss including level, slope and general audiogram shape on these properties of the ABR test in a large clinical group. The study comprised 306 patients (153 male, 153 female) referred for ABR screening to exclude retrocochlear dysfunction. Of 566 ears meeting the inclusion criteria, 85 (15 per cent) failed the test. On follow-up eight ears (3 per cent) were confirmed to have some form of retrocochlear abnormality, seven of which were pathological. All had abnormal ABR results. No cases of retrocochlear abnormality were found in the ABR pass group. In those patients diagnosed as free of retrocochlear problems, the importance of the I-V interval as a primary index of function was confirmed. It displayed a high specificity (>90 per cent) which was largely independent of the level or slope of high-frequency hearing loss. In contrast wave V specificity decreased with increasing loss and increasing slope. Its value as a functional index was limited with losses greater than 70 dB HL in whom specificity fell below 70 per cent. The study concluded that, despite reducing interval availability above 60 dB HL, wave V latency cannot be used as an alternative index because it displays weakening specificity over this range of loss. With the problems inherent in applying latency corrections, the author advocates the use of improved procedures for wave I identification in these cases.

Anomalous screening outcomes from click-evoked otoacoustic emissions and auditory brainstem response tests.

Transiently evoked otoacoustic emissions (TEOAE) and auditory brainstem response (ABR) tests were used in parallel to screen 862 neonates with risk factors for hearing loss. Seven neonates (0.81%) passed on TEOAE screen yet failed on ABR in one ear (six neonates) or both ears (one neonate). This combination of results has been termed 'anomalous'. Examination of audiometric results obtained on follow-up shows that in one ear of one neonate the result was consistent with the later confirmed audiogram shape. The explanation for the anomalous results in the remaining ears is unclear although neural maturation and the effects of hyperbilirubinaemia are possibilities. There were no instances of progressive or retrocochlear hearing loss identified. None of the seven neonates had better ear hearing loss of > or = 40 dB on long term follow-up.

Distortion product otoacoustic emissions for the assessment of auditory sensitivity

Distortion product otoacoustic emissions (DPOAEs) were evaluated in 494 normal and 506 cochlear-impaired human ears, to determine whether DPOAEs depend on factors such as background noise, the shape of the pure tone audiogram, sex and aging, and whether a DPOAE test can perform well in distinguishing normal-hearing from hearing-impaired ears. The amplitudes of DPOAEs were measured at the frequency of 2f1-f2 (f1 < f2, f2/f1 = 1.22, f2 at 1, 2 and 4 kHz) using as stimuli two pure tones at level of 70 dB from an ILO92 Otoacoustic Emission Analyzer. The correlation coefficients between the DPOAE level and the auditory threshold decreased as the background noise levels at 1 kHz and 2 kHz increased. Therefore, it appeared that ears with large background noise levels would be inadequate for the study of DPOAEs predicting the hearing state. The sensitivity (normal-hearing ears identified as normal hearing) and the specificity (hearing-impaired ears identified as hearing impaired) at the equal-sensitivity-specificity condition were 80.7-86.7% at 1, 2 and 4 kHz, and the areas under the receiver operating characteristic (ROC) curves, which were used to estimate the test performance, were 0.88 for 1 kHz, 0.91 for 2 kHz and 0.92 for 4 kHz. Since these results suggest that a DPOAE can be used as a reliable technique for objective auditory tests, it is thought that actual values (DPOAE level: 4.3 dB at 1 kHz, 5.0 dB at 2 kHz and 2.9 dB at 4 kHz) of false-positive (hearing-impaired ears identified as normal hearing) rates corresponding to 5% can be used in clinical evaluation to separate normal hearing from hearing-impaired ears. There was, however, a significant age effect at 4 kHz on DPOAEs in the ears with the same pure tone hearing thresholds, and the areas of the ROC curves in subjects ranging from 10 to 29 years old were larger than in subjects over 50 years (1 kHz: 0.88 to 0.94 versus 0.83 to 0.84, 2 kHz: 0.95 versus 0.89, 4 kHz: 0.95 to 0.96 versus 0.88 to 0.89). Therefore, it is thought that age-adjusted norms may be necessary for the accurate interpretation of DPOAE results.

Effect of inner ear hearing loss on delayed otoacoustic emissions (TEOAE) and distortion products (DPOAE)

The assessment of inner ear hearing loss by means of evoked otoacoustic emissions (EOAE) is already established in practice. Nevertheless, empirical data on the relations between emission and audiologic parameters are required. EOAEs werde measured and analysed in 240 ears with sensorineural hearing loss (excluding cases with conductive and retrocochlear disorders) of 120 patients using ILO88/92 equipment with standard test conditions. Audiologic examination consisted of pure tone audiogram, tympanometry and auditory brainstem responses. The results of TEOAE (Transitory Evoked Otoacoustic Emissions), measured with clicks at 80 dB SPL, and DPOAE (Distortion Product Otoacoustic Emissions), measured with frequencies ranging from f2 = 1 kHz to 4 kHz at 70 dB SPL (L2 = L1, f2 = 1.2 f1), were compared to each other and to the hearing thresholds determined by subjective pure tone audiometry. A significant negative correlation is found between the amplitude of TEOAEs and the average hearing loss in the range of 0.5 to 4 kHz. Similarly, the amplitude of DPOAEs is significantly correlated to the hearing threshold encountered at the higher of the two stimulus frequencies. Nevertheless, the prediction of hearing loss from the response amplitude is not possible because of its large amplitude variations between individuals. The analysis of the relation between incidence of EOAEs and hearing loss shows that in ears exceeding a hearing loss of 34 +/- 4 dB (minimal value of subjective thresholds in the range 0.5 to 4 kHz) no TEOAEs can be registered. For DPOAEs, the responses disappear if the hearing loss at the higher stimulus frequency exceeds 47 +/- 3 dB (limits for 50% OAE incidence are given in both cases). In conclusion, the hearing thresholds of ears exhibiting DPOAEs but no TEOAEs are located between approximately 30 and 50 dB HL. The sharpness of the transition between clear responses and absent responses decreases with increasing age. Therefore, the combination of TEOAE and DPOAE recording with the purpose of hearing threshold assessment is especially useful in young patients. Further evaluation shows that male and female patients do not differ in the hearing loss dependent prevalence of otoacoustic emissions. On he other hand, a systematic but not significant influence of the audiogram shape on the parameters of the discrimination function can be observed: steep audiograms are described with a discrimination function, which drops to zero at higher levels of hearing loss and with a larger slope than shallow audiograms. The comparison of right and left ear emissions of the same patient shows that large amplitude differences occur even in cases of comparable subjective thresholds; missing emissions in one ear are observed if and only if the interaural threshold difference exceeds 30 dB.

Hearing in the FM-bat Phyllostomus discolor: a behavioral audiogram.

Absolute auditory thresholds of six adult lesser spear-nosed bats Phyllostomus discolor (Chiroptera, Phyllostomidae) were determined in a two-alternative forced-choice procedure. Behavioral response to pure tone stimuli could be elicited throughout the tested frequency range of 5-142 kHz. The shape of the average audiogram is characterized by two sensitivity peaks and a pronounced increase of thresholds around 55 kHz, and towards the limits of the tested frequency range. The spectral extent of both sensitivity peaks shows a close relation to the bandwidth of two types of species-specific vocalizations. The first low threshold area (> 10 and < 55 kHz) of the audiogram seems perfectly adapted to the directive call used for intraspecifc communication, whereas the second sensitivity peak, centered around 85 kHz, covers most of the bandwidth of the species' echolocation calls.

Nonsyndromic hearing loss: an analysis of audiograms.

We examined features of the audiograms of 136 individuals, from 28 families, affected by nonsyndromic genetic hearing loss. There were 83 (12 families) with autosomal dominant (AD) loss, 50 (15 families) with autosomal recessive (AR) loss, and 3 (1 family) with X-linked recessive loss. The main audiogram shapes found were sloping (50.3%), residual (26.5%), and flat (21.0%). Specific shapes (ascending and U-shaped) only occurred in 3.7% of AD cases. Audiogram shapes were found to be significantly different between AD and AR families, and showed intrafamilial and interfamilial variability. In the AR group, the main shapes were residual and sharply sloping, and in the AD group, sharply sloping, flat, and gently sloping. There was a significant difference in the degree of hearing loss between AD and AR types, with AD being milder than AR. It has been shown that there is more marked intrafamilial variation in the degree of hearing loss in AD families than in AR ones. The results suggest that the audiograms of nonsyndromic hearing loss are usually nonspecific and that counseling of family members would be better based on the specific family's condition rather than on group information.

ABR Amplitude and Dispersion Variables:Relation to Audiogram Shape and Click Polarity

ABR amplitude behaviour to condensation (C) and rarefaction (R) clicks was investigated in normal ears, ears affected by Ménière's disease and ears with high-frequency hearing loss (HF ears). The wave IV-V amplitude-intensity function was steeper in ABRs evoked by R than by C clicks. This may suggest that two different cochlear generator components, one intensity-dependent as well as one polarity-dependent, contribute to click-evoked ABRs. Wave IV-V amplitude was significantly higher in Ménière ears compared to HF ears in spite of comparable 2-4 kHz hearing loss in the two groups. Hence, audiometric steepness (which is lower in Ménière ears than in HF ears) seems to predict the wave IV-V amplitude decline more precisely than the 2-4 kHz perception threshold. The wave IV-V dispersion variable (SR IV-V) was close to normal in Ménière ears, while wave IV-V was more dispersed in HF ears. In general, C click ABRs were less affected than R click ABRs by 'peripheral' factors (i.e. intensity and audiometric steepness).

BAEP amplitude and dispersion variables: relation to audiogram shape and click polarity

BAEP amplitude and dispersion variables: relation to audiogram shape and click polarity

Progressing cases from low tone sudden deafness to Menière's disease--cochlear impairment in the so-called pre-Menière's disease period

Among 80 patients with low tone sudden deafness (LTSD) who visited our department over the past 15 years, there were 6 cases (7.5%) who subsequently progressed to Menière's disease. The clinical and audiological processes of the 6 patients were studied in detail and the following results were obtained. (1) In these 6 patients, the time between onset of LTSD and the diagnosis of Menière's disease ranged from 4 months at the shortest to 6 years and 8 months at the longest, 2 years and 9 months on average. (2) Two pattern types were seen in the change from LTSD to Menière's disease: changing within a short period of time after recurrence of an LTSD-like attack, and changing after more than one year without recurrent attack. (3) The monoattack-nonrecovered type of LTSD and the recurrent type of LTSD within three months after the onset (short-term prognosis) frequently progressed to Menière's disease. (4) There were no close relationships between subjective symptoms and audiological features in the pre-Menière's disease period (from the onset of LTSD to the recurrence of vertigo with cochlear symptoms). (5) The 6 patients showed various audiogram shapes at the time of progression to Meniere's disease; 3 cases with the slightly rising type, 1 with the high frequency-impaired type, and 2 with the moderate, gradual and flat type. (6) Of the 6 patients, 3 had good hearing during long term observation. At least 2 patients seemed to have the mild type of Menière's disease.(ABSTRACT TRUNCATED AT 250 WORDS)

Noise and vibration interactions: effects on hearing.

There is the suggestion in the literature that vibration may potentiate the effects of noise and may thus increase the risk of hearing loss in a variety of exposure situations. However, in human experimental studies, which, by necessity, are limited to low levels of exposure, the effects measured are relatively small. A very limited number of animal studies have also shown an enhanced noise-induced hearing loss in the presence of vibration, but the scope of these studies is limited. The animal studies (chinchilla) that form the basis of this report were performed using a 30-Hz, 3g rms and a 20-Hz, 1.3g rms cage vibration separately and in combination with continuous noise (95-dB, 0.5-kHz octave band) and impact noise (113, 119, or 125 dB peak SPL) exposure paradigms. All exposures lasted for 5 days. The impact noise exposures were designed to have approximately equal total energy. Temporary and permanent threshold shifts were measured using evoked potentials, and sensory cell loss was measured using surface preparation histology. The results obtained from some of the noise/vibration paradigms showed that such exposures can alter some of the dependent measures of hearing. This effect was statistically significant only for the stronger vibration exposure conditions and was evident primarily in the extent of the outer hair cell losses and in the shape of the PTS audiogram.

Functional hearing loss in children

This report reviewed 39 school-age children diagnosed as having a functional hearing loss utilizing auditory brainstem response (ABR) audiometry during the past 5 years at the Department of Otolaryngology, Kyushu University Hospital in Japan. Twenty-seven cases were females and 12 were males. Seven cases had a hearing loss unilaterally and 32 bilaterally. Although pure-tone audiometry revealed a variety of audiogram shapes, two-thirds of the cases had a flat or saucer-shaped audiogram with a mild to moderately severe hearing loss. ABR audiometry for the frequencies of 1, 2 and 4 kHz indicated a normal hearing threshold in 65 ears of 35 patients, and mild threshold elevations of at least one frequency in the remaining 6 ears of 4 patients. Three illustrative cases were demonstrated, and a discussion was held regarding the features in audiometric tests, and environmental factors surrounding the children with this condition. We emphasized that the physiological hearing measurement such as ABR audiometry should be performed when any discrepancy was noted between the patient's history and results of pure-tone audiometry, because of not infrequent occurrence of functional hearing loss.

Progressive sensorineural hearing loss in childhood

Examination was made of the records of school-aged children with a bilateral sensorineural hearing loss who were seen for audiological assessment in the period 1984 to 1986. These records formed the basis of an investigation, reported in this paper, into the prevalence of progressive sensorineural hearing loss, the causes of hearing impairment in these children, the ages at which deterioriation occurs and the patterns of progression in terms of audiogram shape and symmetry. A figure of 9% was found for prevalence, but arguments are put forward to show that this is probably a minimum figure and that most studies are likely to under-estimate the number of children with progressive sensorineural hearing loss. There is a tendency for the deterioration to be greater in the better ear. The implications of this when assessing the role of hearing aids in causing deterioration is discussed.

Masking of tinnitus compared to masking of pure tones.

In 10 subjects with sensorineural tinnitus (associated with a sensorineural hearing loss and no apparent source for a tinnitus originating elsewhere), the minimum level required to mask the tinnitus was determined for tonal maskers at several masker frequencies. This tinnitus masking pattern was compared to a psychoacoustical tuning curve (PTC) in which the signal frequency and level were determined from tinnitus pitch and loudness matching. Different patterns emerged. One subject showed a near-normal PTC but required high-level maskers across the frequency range to mask the tinnitus. Another subject showed some frequency resolution in the PTC but required low-level maskers across the frequency range to mask the tinnitus. For the remaining eight subjects, the masker levels required to mask the tone were generally higher than those levels required to mask the tinnitus. In addition, it was noted that the tinnitus pitch-match frequency was sometimes associated with an increase or a decrease in threshold sensitivity, or it was found at the low-frequency edge of a steep high-frequency threshold loss. In other subjects there was no apparent relationship between the tinnitus pitch and the audiogram shape.

Survey of attempts to use auditory evoked potentials to obtain an audiogram. Review article.

Click stimuli have been used to elicit ABR in auditory diagnosis but the ABR response is dominated by the activity of high-frequency nerve fibres and it is therefore impossible to deduce hearing at lower frequencies from ABR to clicks. Short tone pips or filtered clicks are also inadequate since the response is still dominated by basal turn, high-frequency nerve fibres. In order to attempt to obtain an audiogram by means of ABR, various noise-masking techniques have been used to restrict the response to more specific regions along the basilar membrane. These included presenting click or filtered click stimuli together with either different high-pass noises in order to obtain a derived ABR or notched noise. Though these techniques have been tested on small groups of normal subjects, they have not been adequately clinically validated on sufficient numbers of hearing-loss patients with various audiogram shapes. When tested on patients with low-frequency hearing loss, inappropriate thresholds have been obtained indicating problems with lower frequencies. Alternatively, other types of auditory evoked responses based on less synchronous neural activity have been studied including the SN10 response and the 40 Hz-MLR. These responses have not been adequately clinically tested. In conclusion the evoked potential techniques have not been completely tested in the clinical situation and several studies have indicated problems with the evaluation of lower frequencies.

Human auditory nerve action potentials and brain stem evoked responses: effects of audiogram shape and lesion location.

• Simultaneously recorded auditory nerve action potentials (APs) and brain stem auditory-evoked responses (BSERs) were correlated with audiogram shape and with location of pathologic condition. High frequency (4 to 8 kHz) hearing loss (1) prolongs AP and BSER latency, (2) shortens the interval between the first AP peak (N1) and the fifth BSER peak (V), and (3) creates relatively large latency differences between condensation and rarefaction responses (thus bringing into question the common practice of combining condensation and rarefaction responses). Ears with retrocochlear deficits in the subjects in the study were detected reliably by prolonged N1to V interval and increased BSER peak V latency. The reliability of these retrocochlear signs was further increased by allowing for the effects of audiogram shape. Another retrocochlear sign, termed inappropriate AP preservation, was positive in 40% to 50% of the retrocochlear ears. (Arch Otolaryngol103:605-622, 1977)

Clinical Findings And Diagnostic Problems In Sensorineural Low Frequency Hearing Loss

The otological and audiological findings in 39 patients with sensorineural low frequency hearing loss are reported. This type of perceptive hearing loss is difficult to distinguish from true conductive hearing losses due to the air conduction audiogram shape and the invalidity of bone conduction determinations showing a false “air-bone gap”. This may lead to surgical treatment of a perceptive hearing loss, as reported in the four case histories. By various audiological tests, contradictory information may be obtained. In our material, Bing's test and absent acoustic reflexes indicated a conductive disorder in 25% of the ears. The final differentiation may require cochleography. The hearing loss may be diagnosed as Meniere's disease. In our material only 17% complained of tinnitus and no patients had vertigo. Consequently, we find sensorineural low frequency hearing loss to differ from Meniere's disease. Our material comprises different etiological types of perceptive low frequency hearing loss. One type was inherited as an autoso-mal dominant trait, another type due to cochlear malformation probably also inherited. and a third group showing diverse audiological results. When the diagnosis is established, the patients may be treated successfully by specially constructed hearing aids.

Human Auditory Nerve Action Potentials and Brain Stem Evoked Responses: Effects of Audiogram Shape and Lesion Location

Simultaneously recorded auditory nerve action potentials (APs) and brain stem auditory-evoked responses (BSERs) were correlated with audiogram shape and with location of patholgoic condition. High frequency (4 to 8 kHz) hearing loss (1) prolongs AP and BSER latency, (2) shortens the interval between the first AP peak (N1) and the fifth BSER peak (V), and (3) creates relatively large latency differences between condensation and rarefaction responses (thus bringing into question the common practice of combining condensation and rarefaction responses). Ears with retrocochlear deficits in the subjects in the study were detected reliably by prolonged N1 to V interval and increased BSER peak V latency. The reliability of these retrocochlear signs was further increased by allowing for the effects of audiogram shape. Another retrocochlear sign, termed "inappropriate AP preservation," was positive in 40% to 50% of the retrocochlear ears.

Noise-Induced Hearing Losses in Cats: Effects of Bandwidth, Intensity, and Exposure Duration

The cat's auditory threshold was determined with behavioral methods before and at intervals after exposure to intense thermal noise. Using two bands of noise with different upper cutoffs (500–504 and 500–508 kHz) and two intensity levels, exposure duration was gradually increased (three exposures at each D) until PTS occurred for each cat. The shapes of the postexposure audiograms were determined, and recovery curves were traced. The shapes of the postexposure audiograms were found to differ significantly as a function of the upper cutoff limits, the intensity levels, and the different exposure durations. For example, the frequency showing the greatest loss was not invariable across all conditions. In addition, there were significant individual differences in both the amount of TTS and the shape of the postexposure audiogram. The relationship between individual susceptibility to TTS and PTS was also determined and will be reported.

Audiogram-Average Methods and SRT Scores

Pure-tone audiograms and SRT scores on 535 audiology patients were utilized. Binaural percent hearing loss and audiogram summary or average according to several methods were computed for each subject. Each subject had an SRT score obtained with a common clinical test. Product-moment correlations were computed between each pure-tone audiogram percent or summary method and SRT scores, with subjects categorized according to SRT test given and audiogram shape. Most between-test correlations were over 0.70 and many were over 0.85. In general, the AMA and the Fowler methods had less high correlations with SRT than the other methods. The two-frequency average had a general superiority over other methods and may be considered the method of choice for relating pure-tone audiograms to SRT. However, the differences among methods, including the Fowler and AMA percent methods, were small.