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Hearing surveillance is a mandatory requirement of new EC Regulations. Dr Stephen Karmy believes that audiometry has an important part to play in a company's hearing protection policy and aids compliance with new legislation.
The importance of noise types, which are used in audiometry, is pointed out and theory of noise is discussed. Besides practical examples of noise are compared with theoretical considerations. Comparison shows that exact theoretical definitions are mostly not fulfilled. In general, however, common types of noise are of satisfactory quality.
Observations on the ultrasonic perception of noise-impaired persons gave rise to use the high frequency audiometry described by Fletcher for the early recognition of noise-induced damages. Using commercial equipment we found that the earpiece was not adapted to high frequency conditions. The adaptation problem and ways of modification are described in detail. After having improved the coupling features reproducible hearing curves were obtained. Examinations were carried out on workers, whose noise exposure exceeded the critical intensity by only a few dB. The following 3 categories of impairment were found: 1. Normal hearing between 125 and 8,000 Hz as well as in the high frequency region. 2. Unsignificant noise-induced impairments between 125 and 8,000 Hz; no high frequency hearing. 3. Acoustic hearing; no high frequency hearing. The results are discussed. It is supposed that high frequency hearing losses due to noise and chemical noxious exposure (streptomycin) are valuable in diagnostics and prognostics. Accordingly persons are to be assessed as noise sensitive, when there is no more high frequency hearing before practising noise work.
A case of nonorganic hearing loss combined with noise-induced hearing loss and the necessity of differentiating them by Electric Response Audiometry in legal assessment is described. A second example deals with monaural functional hearing loss induced by ill-treatment. Finally is reported on a bilateral neurinoma of the acoustical nerve with an extrem auditory fatique and the impossibility to detect evoked potentials.
Many studies have established high-frequency audiometry norms. Unfortunately the majority presents different averages for each decade, sex and frequency together with standard deviations. In order to solve these problems we established our norms on a widespread audiometer for each sex based on a strictly normal hearing sample. We calculated the linear regression between age and hearing loss for each frequency. We propose a set of equations to predict the "normal" threshold of a subject in function of age and sex.
The auditory apparatus of two strains of mices with normal audition is compared to that of two substrains with genetic auditory impairment. Audiometry by auditory evoked potentials at the inferior collicular level indicates complete deafness for one substrain and a 40-48 dB S.P.L. hearing loss at all frequencies for the other. Scanning and transmission electron microscopy demonstrate hair impairment of the external hair cells and degeneration of the chondriosome for the two deaf substrains.
OBJECTIVE: To obtain the residual hearing by using multi-frequency steady-state response test in a group of deaf children and to compare the results with that of ABR. METHOD: Both sides of ears of 278 deaf children had been tested while they were asleep. RESULT: Positive incidences of MFSSR at 0.5, 1, 2, 4 kHz are 33.09%, 70.50%, 44.96%, 19.42% (left ears) and 33.81%, 66.91%, 41.07%, 17.63% (right ears) respectively. Except 4 kHz, the ratios at the other three frequencies are significant higher than that of ABR. CONCLUSION: MFSSR is a promising objective audiometry, this kind of test could provide frequency-specific information for hearing diagnosis.
A total of 251 men at the age of 23 to 50 have been examined with the use of audiometry and dynamic impedance metry who had obtained various doses of radiation connected with the work at the Chernobyl Power Plant. It was established that in 57.8% of the cases the audition was within the physiological norm and in 42.2% various forms of audition derangements were diagnosed.
Auditory steady-state response (ASSR) audiometry is a commercially available tool that is used to predict behavioral auditory threshold levels. Its particular value stems from the technology's ability to measure frequency-specific responses in the background electroencephalogram to auditory stimuli presented across a broad range of frequencies and sound pressure levels. It is clearly of benefit when used to assess threshold levels in infants and children with severe-to-profound hearing impairment (i.e., cochlear implant candidates). Although numerous authors have provided evidence of the usefulness of ASSR testing, their reports have concerned patients whose middle ear impedance measures were normal. We report the cases of 2 patients who, following improvement of abnormal middle ear impedance values, experienced a marked improvement in measurable thresholds by ASSR testing.
Fifty-eight cases with a presumptive clinical diagnosis of perilymphatic fistula (PLF) are described with the results of a positional audiometric test designed to detect the presence of air in the cochlea. All patients underwent tympanotomy and observations of the middle ear are recorded together with the results of treatment. A definite leak was found in 33 cases and none in 25, but grafting of the round and oval window was performed in all but 10 cases. Pure-tone audiometry was performed before and after a 30-minute period of positioning the patient horizontally with the affected ear uppermost. A change in audiometric thresholds was noted in the group where a presumptive diagnosis of PLF was made, including some of those not found to have leaks at operation. However these changes were not observed in the positional tests of a group of 22 patients with hearing losses attributable to other causes. Also, an abnormal air-bone gap was noted in the PLF group compared with the other group. Although the original two-frequency criteria of earlier studies applied to the positional test did not predict the operative findings (leak or no leak), new data on frequency specific changes are presented. It is possible that fistulas at the oval window may be associated with positional threshold change at 500 Hz, and those at the round window with changes at 8 kHz.
OBJECTIVE: To edit the sentence list for mandarin speech test materials (MSTM) and to test their equivalence in order to use the list as routine clinical speech tests for evaluation of cochlear implants and hearing aids in different stages of the intervention and rehabilitation. METHODS: Firstly, two groups of professionals were set up: one for establishing the principles of the edit, another for experiments. The criteria to guide the selection of spoken sentences were as following: (1) suitable for everyday speech audiometry, esp. clinically usage; (2) a normal sampling of everyday spoken sentences in mandarin. Totally, 300 sentences were selected in 30 lists for the experiment. The record cassette was used by a male speaker. The college students (54 persons,54 ears) with normal hearing participated in the equivalence test. Two statistic methods were used for equivalence analysis. RESULTS Through speech tests and statistic analysis, 2 sets with 29 lists (290 sentences) were selected as our equivalent lists for further evaluation and clinical trial. CONCLUSIONS: By setting up the strict criteria of selecting sentences, speech test method and statistic analysis, 2 sets of 29 lists (290) sentences were chosen as our speech evaluation materials, but it was necessary for further analysis in different laboratories and clinics. The sentence lists should also get used for hearing impaired subjects, hearing aid users and cochlear implant recipients.
Behavioral audiometry is based on observation of overt responses to controlled auditory stimuli, as contrasted with electrophysiologic procedures, which involve electrophysiologic monitoring or direct recording of the bioelectric correlates of the original signal. When reinforcement is added to the behavioral procedures, the infant or young child provides highly reliable responses, and it is possible to test most infants 6 months of age and older with these procedures. The combination of both behavioral and electrophysiologic procedures can resolve most clinical questions regarding the auditory function of young infants and children.
The own experiences with the computer microsystem for hearing evaluation "Audiocomp" were presented. The air and bone conduction thresholds as well as the others suprathreshold testing were performed by computer. The reproducibility of results were better than in standard audiometry. The influence of the examined person is lowered making the testing more objective.
The use of microcomputer for the Brain-Stem Response Audiometry was discussed. The obtained results using the computer system, the methodology and technique of hearing examination were presented. Special attention was called to modelling aspects of the components of the registered signal and the instability of generators in the neuronal structures of the acoustic pathway.
The following findings have been obtained as a result of investigating the patients with TM disorder before and after correction of the mandibular repositioning as it was considered that, if the sound transmitting middle ear hearing system which undergoes change along with the morbidity in progress shows reversible changing aspect in response to the ebb and flow of the morbidity, it would serve as quantitative diagnostic criteria regarding the repositioning by means of bite-plane therapy. Changes were observed between before and after repositioning in 3 item measurement. The values of static compliance, impedance and pressure of middle ear were reduced to the level of those in healthy subjects. Consequently, the following conclusions were reached: Impedance audiometry serves as quantitative judging criteria regarding the repositioning of the mandible by means of bite-plane therapy.
Data obtained from electrophysiology are insufficient both for the audioprosthetist and for the speech therapist. In order to meet the requirements for the increasingly early equipping and training of deaf children, we have developed in the Bordeaux Audiology Laboratory an audiometric strategy making it possible to obtain, as early as 5 to 6 months old, bone curves on the vibrator, and air curves on the head-set. In addition to the auditive information that can be obtained, the test described forms, by its design, the starting point of early training and parental guidance. Its success is based on the relationship that is established between the child and the investigator. Early audiometry is possible. It is essential prior to any therapeutic approach.
We carried out a transnasal insufflation test according to Blom and Singer on 27 laryngectomy patients as well as a speech communications test with the help of reverse speech audiometry, i.e. the post laryngectomy telephone test according to Zenner and Pfrang. The combined evaluation of both tests provided basic information on the quality of the esophagus voice and functionability of the speech organs. Both tests can be carried out quickly and easily and allow a differentiated statement to be made on the application possibilities of a esophagus voice, electronic speech aids and voice prothesis. Three groups could be identified from our results: 1. Insufflation test and reverse speech test provided conformable good or very good results. The esophagus voice was well understood. 2. Complete failure in the insufflation and telephone tests calls for further examinations to exclude any spasm, stricture, divertical and scarred membrane stenosis as well as tumor relapse in the region of the pharyngo-esophageal segments. 3. Organic causes must be looked for in the area of the nozzle as well as cranial nerve failure and social-determined causes in the case of normal insufflation and considerably reduced speech communication in the telephone test.
Click-evoked oto-acoustic emissions (EOEs) and speech audiometry were recorded in a group of normally hearing subjects (n = 56 ears), and a group of patients demonstrating sensorineural hearing loss due to presbycusis (n = 39 ears). Correlations were made between detection-threshold of EOEs, speech reception threshold (i.e., lowest hearing level at which the subject can repeat 50% of a message), and discrimination score (i.e., discrimination score determined 35 dB above the speech reception threshold). EOEs have never been observed when speech reception threshold was equal to or greater than 35 dB HL. EOEs were always found when speech reception threshold was equal to or lower than 25 dB HL. Moreover, the detection-threshold of EOEs increased when increasing speech reception threshold. On the other side, there was not a good correlation between the discrimination score and the detection-threshold of EOEs. Thus, complementary information on outer hair cell degenerative changes in presbycusis could be deduced from these data.