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High-frequency audiometry: air- and electric bone-conduction.

Normative values have been obtained for high-frequency air- and electric bone-conduction thresholds in different age groups. Reproducibility with both methods is of the same order of magnitude as with conventional audiometry. The two thresholds can be compared and the air-conduction/electric bone-conduction gap obtained by transforming the electric bone-conduction values to a dB notation by means of a formula containing a frequency-dependent constant.

Adult↗

Computerized audiometry--a facility to prevent hearing damages caused by noise.

A computerized audiometer has been developed to perform pure-tone manual or fixed-frequency Békésy audiometry. A number of statistical evaluation programs are part of the integrated audiometer. It means that even small but statistically certain changes in hearing thresholds can be revealed at an early stage.

Audiometry↗

Brainstem-evoked response audiometry: normative data from the preterm infant.

Brainstem-evoked response audiometry (BERA) was performed on 40 preterm infants who had low neonatal risk scores. Mean latencies for waves I and V were obtained from four age-groups, 33-34, 35-36, 37-38 and 39-40 weeks conceptional age. The results indicate that BERA is a valuable and reliable tool in assessment of auditory function in the preterm infant. Also for classification of abnormality it is recommended that 2 standard deviations from the mean latency of wave V be used.

Audiometry↗

Contingent negative variation audiometry in children.

The aim of the present work was to establish whether contingent negative variation audiometry (CNV-A) is applicable to children. In a group of 23 children aged 5-7 years, only 10 generated clearly recognizable CNV when tested with the method successfully used in adults. When the procedure was modified by prolonging the S1-S2 interval and by introducing attractive slides to serve as the S2 stimulus and by adopting a slower repetition rate, 9 children randomly selected from the former group generated high-amplitude CNV (10.1 +/- 4 mu V). The CNV-A measurements involving a longer auditory stimulus (S1), lasting nearly to the beginning of S2, and an even slower repetition rate were equally successful in 18 children aged 3-5 years, who generated CNV with an average amplitude of about 9 mu V (range 5-15 mu V). We believe that the basic problem of successful CNV recording in children is to attract their attention to the signals of the CNV paradigm. The child's attentiveness decreases rapidly. The mean difference and the absolute mean difference between the subjective hearing threshold for white noise and the perception threshold for white noise as determined by CNV-A were as follows: 8.8 +/- 8 dB (both values) for the older group, and 3 +/- 10.4 and 8.6 +/- 6.5 dB, respectively, for the younger group. These differences are quite comparable to those obtained in adults. We therefore believe that CNV-A, used in combination with the behavioral method, provides a most reliable estimate of the child's hearing threshold in dubious situations.

Age Factors↗

Threshold sensitivity and frequency specificity in auditory brainstem response audiometry.

Frequency-specific electric response audiometry can be performed on difficult to test young children if the child is sedated and proper choices are made of acoustic stimuli and recording parameters, although certain compromises are necessary. A very satisfactory sedative is secobarbital, administered intramuscularly in doses related to the weight of the child. As stimuli we recommend '2-1-2' tone bursts at 500, 1 000, 2 000, and 4 000 Hz: i.e., with a rise and fall of two periods and a plateau of one period of the modulated tone. A very robust and sensitive response that is not significantly modified by the sedation and is effective for all four frequencies is the P6-SN10 of the early brainstem sequence. To record this complex favorably requires a bandpass input filter of the Butterworth type with pass-band (at -3 dB) from 50 to 1 700 Hz and rejection rates of 24 dB/octave. With this combination, polarity of stimulus is unimportant and sweep time, rate of stimulation and number of responses averaged may be selected for convenience and simplicity. A routine that requires about an hour of testing time is described and the necessary correction factors are given for estimating a child's behavioral pure-tone thresholds. We believe that our threshold estimates are generally correct within 10 dB, and are sufficiently frequency-specific for proper selection of a hearing aid.

Acoustic Stimulation↗

Brainstem electric audiometry: is routine sedation necessary?

Decreased EEG and EMG waves in sedated adults might produce more sensitive and better defined brainstem electric response. This was investigated by comparing the brainstem electric response to click stimulation in 10 adult volunteers before and during sedation with chloral hydrate. The results showed that there is no increase in sensitivity of the test in cooperative and relaxed adult subjects. The definition of wave I did not improve after sedation. It is therefore concluded that routine sedation is not advantageous in brainstem electric response audiometry in cooperative subjects.

Adolescent↗

High-frequency audiometry using precision earphones: reliability under laboratory and field conditions.

New circumaural earphones were tested in the frequency range from 100 Hz to 20 kHz and compared to commonly used supra-aural earphones. The circumaural earphone HD 230 (Sennheiser) generates test stimuli at up to 20 kHz with almost constant sound pressure levels when its pos ed on an artificial ear. The reproducibility of hearing threshold mea ed with a new microprocessor-controlled Békésy audiometer using the ne was nearly as good as under free-field conditions. The practicabil diagnostic value of high-frequency audiometry have been demonstrated er field conditions. For this application, the good sound attenuation these earphones (30 dB above 1 kHz) are important. High-frequency he ds of healthy pupils and of pupils with a history of otitis media are kHz, the hearing threshold level difference between both groups reached 20 dB.

Adolescent↗

Electrical high-frequency audiometry. Preliminary medical audiologic experience.

This paper reports our clinical experiences with the electrical high frequency audiometer (EHFA)-Tonndorf, used in conjunction with conventional audiologic site of lesion testing. The EHFA is routinely used in the site of lesion hearing evaluation battery. We are reporting on the first 100 subjects, aged 6-85 years, seen in otologic/neurotologic consultation for complaint(s) of hearing loss, tinnitus, vertigo, ear blockage alone and/or in combination from 1983 to 1985. The significance of the data obtained suggests that: (1) Patient responses with EHFA are influenced by age, degree of hearing loss, degree of ear disease, site of lesion and disease, noise exposure and ototoxicity. (2) The degree of hearing loss as well as symmetry (asymmetry) of the loss affect the EHFA responses. (3) Responses to EHFA can be correlated with subject group classification. Five groups were well defined based upon degree and symmetry (asymmetry) of the hearing loss. (4) Electrical high-frequency audiograms (EHFAs) can be classified into five different patterns of response. (5) EHFA should be part of a site-of-lesion audiometry test battery.

Adolescent↗

Clinical applicability of insert earphones for audiometry.

Insert transducers for audiometry are available which may offer significant advantages over older 'standard' headphones. Clinicians have remained cautious in using such devices due to the paucity of experimental data demonstrating their comparability with more widely used devices. The purpose of this investigation was to compare and contrast pure-tone audiometric thresholds obtained using insert earphones with those measured utilizing conventional supra-aural transducers in normal and hearing-impaired subjects. A second purpose was to examine the differential effects on the hearing threshold level of two coupling systems for the insert device. There were no clinically significant differences among pure-tone thresholds measured with the three earphone/coupler arrangements for subjects with normal and impaired hearing. Advantages and limitations of insert earphones are discussed.

Acoustic Impedance Tests↗

A study of the reliability of automatic audiometry by the frequency scanning method (Audioscan).

This study was designed to evaluate the reliability of Audioscan audiometry. Repeated measurement of hearing thresholds were conducted using the frequency scanning method specific to Audioscan. These thresholds were compared to those assessed by means of the fixed-frequency Békésy method. Overall, 24 subjects participated in this study. They had to have a significant history of occupational or extra-occupational noise exposure and exhibit at least a slight hearing loss. The reliability of Audioscan proved to be comparable to the Békésy method for thresholds measured at conventional frequencies, when the sweep speed was set at 10 or 20 seconds per octave and the step size at 5 dB. The measurement error typically fell between 3.5 and 4.5 dB, a range of values that compares well with those obtained with the Békésy method under optimal conditions. The notches depicted by the Audioscan are reproducible and can be described by means of several parameters such as the frequency localization of the notch, the depth of the notch and the level of the notch.

Adolescent↗

Brain stem electric response audiometry and middle ear effusion.

Brain stem electric response audiometry has been performed in a group of 41 difficult-to-test children under the age of 8 years. All ears were examined with the pneumatic otomicroscope prior to determination of response thresholds, and middle ear effusion found in 24 (29.3%). Seven of the 14 children requiring hearing aid amplification had fluid in 12 ears (42.9%). The importance of early recognition and treatment of middle ear pathology in children with sensori-neural hearing loss is stressed, and routine otomicroscopy by the attending otologist is recommended.

Audiometry↗

High frequency audiometry. Clinical aspects.

For 2 years past a previously described quasi-free-field high frequency audiometer delivering pure tones from 4 to 20 kHz has been incorporated in the audiological test battery. By this technique it is possible to obtain reliable and reproducible thresholds above the age of 8--9 years. In several case histories it is illustrated how high frequency audiometry (HFA) contributes to a better audiological diagnostic and it is predicted that HFA is of value in research studies on presbycusis, ototoxicity, noise vulnerability, and in hereditary studies on deafness. The physiological presbycusis demands normative reference values for each age decade. Many other factors, however, can cause an impaired high frequency hearing which is a severe limitation to the diagnostic value of abnormal findings.

Adult↗

Hearing aid selection by brainstem audiometry.

Hearing aid selection and adjustment by means of brainstem audiometry was tested in 29 hearing impaired children. A projection procedure is introduced which employs normal and pathological intensity-amplitude functions. This method enables determination of some basic properties of appropriate hearing aids, such as average gain, type of compression, compression factor and onset level. Hearing aid evaluation is discussed for two examples of conductive and sensorineural impairment.

Adult↗

Stapedius reflex test, brainstem audiometry and opto-vestibular tests in diagnosis of acoustic neurinomas. A comparison of test sensitivity in patients with moderate hearing loss.

The stapedius reflex test, brainstem audiometry and the opto-vestibular tests for identifying acoustic neurinomas (AN) were evaluated and compared in a study of 21 patients with radiologically or surgically verified AN and a pure tone average not exceeding 60 dB HL. The stapedius reflex test results were interpreted according to the criteria developed at this clinic. The stimuli for the auditory brainstem response (ABR) were 2 kHz haversine waves and 4 kHz square waves. The vestibular examination consisted of a caloric test and the recording of eye-tracking and gaze nystagmus. In the cases studied the stapedius reflex test gave 1 false-negative result and ABR none. The ENG gave 3 false-negatives whereas the results of speech discrimination tests were misleading in no fewer than 1/3 of the cases. The results of the different tests were directly correlated but correlation coefficients did not exceed 0.65. Tumours larger than 15-20 mm showed a different test pattern than those below that size: stapedius reflex response, ABR and caloric response were eliminated and all of these patients had abnormal optomotor function. It is suggested that an optimal routine test procedure should consist of a pure tone audiogram, supplemented by ABR or the stapedius reflex test. Opto-vestibular tests may be of value in a preliminary estimation of tumour size.

Audiometry↗

Stimulus waveforms used in brainstem response audiometry.

Clicks and tone-bursts are the most widely used stimuli in brainstem response audiometry. The acoustic click waveform is not only dependent on electric pulse length, but also on the type of transducer, ear coupling and measuring method employed. On the other hand, acoustic tone-bursts are more precisely defined by the electric stimulus-parameters since they show less variation under the same experimental conditions. Acoustic cancellation with alternating polarity electric stimuli is also better with tone-bursts.

Acoustic Stimulation↗

A comparison of 2-dB and 5-dB step size in pure-tone audiometry.

With the purpose of comparing test-retest reliability, pure-tone audiometry with a step size of 2 and 5 dB using the ascending technique was performed on two groups of subjects. One group consisted of 10 normal-hearing subjects and the other of 10 subjects with moderate cochlear hearing loss. The statistical analysis of the overall estimation of standard deviation obtained with the different step sizes showed no significant difference in any group. However, at 3 000 and 4 000 Hz in the cochlear group a significantly lower standard deviation was obtained with the smaller step size. The number of threshold crossings required to fulfil the threshold criterion increased significantly with the smaller step size.

Adolescent↗

Clinical application of brain-stem audiometry.

Based on the examination of 249 consecutive patients, the usefulness of brain-stem response audiometry in a major audiological clinic was evaluated. Auditory brain-stem responses were performed either for hearing threshold determination (67 patients) or for assessment of retrocochlear hearing loss (182 patients). The results demonstrate that ABR is a reliable method for the estimation of hearing thresholds in non-cooperative subjects. The rate of false positives was 5% and no false negatives were found. In combination with caloric testing, ABR is considered a valuable testing procedure in the audiological clinic and it may form the basis for submission to brain imaging examination when a suspicion of retrocochlear hearing disorder is raised. Concerning the diagnosis of retrocochlear hearing disorder, no false negatives have yet been found, while a rate of 13% of false positives has been indicated.

Adolescent↗

The use of pure-tone audiometry in the assessment of gentamicin auditory toxicity.

The results of previous studies of gentamicin auditory toxicity have depended largely on the criteria set for a significant change in hearing threshold. This paper proposes a design for future studies of aminoglycoside toxicity based on an investigation of factors other than aminoglycoside therapy which may influence the measurement of hearing threshold. Audiometry can be performed reliably in a ward but a patient's condition has both temporary and permanent effects on hearing threshold. Ototoxicity cannot be detected by assessing hearing after aminoglycoside therapy. However, an audiogram taken at the start of treatment may be misleading if the patient is seriously ill. Permanent hearing loss may be due to factors other than aminoglycoside therapy so that future studies must be controlled.

Audiometry↗