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Results for “Bone Conduction”

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At least 19 recordsLinked to original sources

PubMed1977

Calibration force levels for bone conduction vibrators.

Two bone conduction vibrators (Radioear B71 and B72) and a headband (Radioear P-3333) have been developed to meet specifications of both the International Electrotechnical Commission and the American National Standard Institute. Pure-tone thresholds for air conduction and bone conduction were obtained from 24 normal-hearing young adults at audiometric frequencies between 250 and 4000 Hz. Results of this study are in good agreement with the standard air conduction threshold sound pressure levels (ANSI) and with bone conduction threshold force levels reported in the literature.

Adult↗

PubMed1989

[Evaluation of hearing in patients with otospongiosis based on direct measurement of bone conduction].

The conventional bone conduction audiometry does not allow an objective assessment of hearing in patients with otospongiosis. We evaluated a new method of direct bone conduction audiometry with the stimulator applied to the promontory intraoperatively. A comparison of conventional and direct bone conduction audiometry thresholds was made in 100 patients in various stages of otospongiosis before stapedectomy. A significant correlation between hearing thresholds obtained by both methods was observed for all frequencies tested (500, 1000, 2000 and 4000 Hz). The direct bone conduction method was at least 30 dB more sensitive for all frequencies. Interestingly, the average direct bone conduction threshold curve did not exhibit a Carhart notch at 2000 Hz compared to the conventional method. We concluded that our bone conduction technique enabled a better assessment of cochlear reserve in patients with otospongiosis.

Adult↗

PubMed1978

Audiometric bone conduction.

Audiometric bone conduction test data are obtained with a unit that permits comparison with a recognized standard because the unit can be calibrated to operate within specified limits. Proper calibration of the unit is necessary if the equipment is to be accurate. Two procedures can be helpful in determining the need for calibration: the average loss method and the input voltage measurement method. Neither should supplant calibration, but each offers a means of checking the output of the unit. Confidence in auditory test data is increased when there is a high degree of consistency among the various tests; the availability of several different tests in the audiometric series can be used to an advantage then in a determination of consistency. An additional opportunity to ascertain the existence of consistency is present when tuning fork tests are employed as part of the total evaluation. The use of a masking stimulus in the nontest ear simultaneously with the presentation of the test tone to the test ear can be extremely useful in defining the type as well as the extent of the hearing loss. Presentation of the test tone and the masking stimulus in controlled discrete steps is the key to the interpretation of masking results.

Acoustic Stimulation↗

PubMed1991

High-frequency air-conduction and electric bone-conduction audiometry. Comparison of two methods.

Threshold values for 147 subjects (9-43 years old) were measured with a high-frequency (HF) air-conduction (AC) (Interacoustics AS 10 HF) and an electric bone-conduction (EBC) (Audimax 500) audiometer. In addition, the reproducibility of these methods was studied in another group of 24 subjects. The results confirmed the previous findings of Okstad et al. (1988) that the electric current (i) used as a stimulus in the Audimax 500 audiometer can be converted into decibels with a correction factor of 40 log (i) re 1 mA as Tonndorf & Kurman (1984) have proposed. However, an additive frequency-dependent correction is needed to obtain similar loudness sensation increases with these audiometers. Reproducibility with the EBC audiometer was better than with the AC audiometer, especially in the HF range.

Adult↗

PubMed1991

High-frequency air-conduction and electric bone-conduction audiometry. Age and sex variations.

208 subjects representing both sexes and five age groups (15-70 years) were examined to obtain age-related threshold values for high-frequency (HF) electric bone-conduction (EBC) audiometry. The measurements also included conventional pure-tone audiometry and air-conduction (AC) HF (8-18 kHz) audiometry. The measured EBC thresholds were comparable to the values obtained with AC audiometers, and were equal to ISO standards at the frequencies of 0.5-6 kHz. The 15- and 20-year-old groups' EBC thresholds at 8 kHz were equivalent to thresholds of 15-year-old people from a cross-sectional material in Northern Finland. Thresholds deteriorated as a function of age, particularly in the HF range. The males had poorer thresholds than the females, especially in the age groups of 40 and 60 years. This could be attributed mainly to their greater noise exposure. The EBC method is quite practical and reliable for routine clinical measurements, but the dynamic range of the audiometer limits its use to relatively young subjects.

Adolescent↗

PubMed1979

Auditory brain stem evoked responses to bone-conducted signals.

Auditory brain stem evoked responses to air-conducted and bone-conducted signals were recorded in subjects with normal hearing and in subjects with conductive hearing loss. In normal subjects, the latency to wave V for bone-conducted signals was approximately 0.5 ms longer than the latency for air-conducted signals delivered at the same sensation level. In conductive hearing loss, the separation of the latency-intensity functions for air conduction and bone conduction (corrected for the 0.5-ms delay) provided a valid estimate of the behavioral air-bone gap in the 1,000- to 4,000-Hz region.

Audiometry, Evoked Response↗

PubMed1992

High-frequency audiometry. Masking of air- and bone-conduction signals.

Interaural attenuation has been investigated for both air-conduction and bone-conduction signals in the frequency ranges 0.25-18 and 0.25-16 kHz respectively. Ear canal occlusion is recommended when using the Koss HV/1A earphone for BC masking, as acoustic transmission occurs through the headset in the high-frequency range. Minimum masking levels for 1/3-octave filtered white noise were established for bone-conduction signals in the frequency range 8-16 kHz. Central masking of bone-conduction signals proved to be of the same order of magnitude in the conventional- and high-frequency ranges, while the cross-masking level was approximately 10-15 dB lower above 6 kHz. Recommendations are made for a masking procedure in the high frequency range.

Acoustic Stimulation↗

PubMed1991

[Otoacoustic emission cochleogram evoked by bone conducted stimulation].

As bone conducted stimulation, tone bursts of different frequencies were applied through the forehead in 7 normal-hearing subjects. Binaural evoked otoacoustic emissions (EOAE) were then recorded simultaneously, which saved one half of the time required for conventional monaural recording. Analysed with autoregressive modeling, the main echo of EOAE was a narrow-band sound with a stimulus dependent central frequency. It was suggested that the generation site of EOAE was near to that cochlear portion stimulated by the corresponding frequency. The latency of EOAE, although independent of the stimulus intensity, tended to be shorter at higher stimulus frequencies. This was possibly due to the differences in the distances from the generation sites of the otoacoustic emissions to the tympanic membrane. Recordable otoacoustic emissions were evoked by tone bursts of 1.0, 2.0, 3.0 and 4.0 kHz in all the 14 normal ears except one at 4.0 kHz, and 10 and 7 ears by tone bursts of 0.5 and 6.0 kHz, respectively. Emission cochleogram was obtained when the means of EOAE detection thresholds were plotted in an audiogram format. The lowest threshold was found at 1.0 kHz. This might be related to the middle ear resonance frequency of 1100 +/- 230 Hz. The technique of simultaneous recording of binaural EOAE and plotting of emission cochleogram described in this paper is clinically useful as a means of objective evaluation of hearing.

Adult↗

PubMed1990

The British experience of an implantable, subcutaneous bone conduction hearing aid (Xomed Audiant).

Implantable bone conduction aids are potentially an important advance for those with a conductive hearing impairment. One system (Xomed Audiant bone conductor), which uses electromagnetic induction to vibrate a subcutaneous implanted skull magnet, has now been implanted in sufficient patients in the United Kingdom, for enough time, for its indications to be evaluated. Seventeen of the total of 18 patients that have been implanted, satisfied the average threshold criterion for suitability for implantation (average bone conduction over 0.5, 1 and 2 kHz of 25 dB HL or better) yet only 10 of the 17 (59 per cent) currently use their Audiant aid. This was not because of technical reasons but was mainly influenced by the previous type of amplification. Current usage of a body level processor was 100 per cent) (6 of 6) in those that previously could only use a conventional bone conduction aid because of bilateral congenital or acquired atresia of their external auditory canals. In comparison, usage was only 36 per cent (4 of 11) in those that could potentially use a conventional ear level aid albeit with problems such as the discharge from active chronic otitis media. This relative non-use was considered due to a lack of power of the ear level processor and the general unwillingness of patients to change from an ear level to a body level device.

Adolescent↗

PubMed1976

Early bone conduction hearing aid devices.

The concept of bone conduction hearing is old. By the 16th century the conduction of sound by a rod or the staff of a spear was reported by a number of writers; however, these writers considered these phenomena as a curiosity rather than having practical value. In the 17th century, John Bulwer and George Sibscota, both interested in the deaf and their education, applied the bone conduction phenomenon as an aid to defective hearing. Soon, independent reports from Germany, France, and Italy also described bone conduction rod devices as aids to impaired hearing. In 1879, the Audiphone, a hearing fan that operated by bone conduction, was patented. The invention of the Audiphone triggered the development and sale of a number of similar devices that had considerable popularity until the invention of the carbon-electric hearing aid in the early 1900s.

Bone Conduction↗

PubMed1992

Bone conduction implants: transcutaneous vs. percutaneous.

Clinical experience with transcutaneous bone conduction implants has demonstrated that they are most beneficial for patients with purely conductive hearing loss in at least one ear. Percutaneous bone conduction implants, however, have been reported to provide adequate benefit for patients with mixed hearing loss with bone conduction pure-tone averages up to 45 dB HL (Tjellstrom, 1989). The results of 24 Xomed Audiant osseointegrated bone conduction hearing devices (including a clinical trial on two patients using a new, larger magnet [Neodynium Iron Boron]), plus the results of eleven patients implanted and fitted with the percutaneous bone-anchored hearing aid are reported. Aided results with these devices will be presented. In addition, general comparisons of benefit obtained with the two devices will be made for patients who exhibit similar hearing losses. Finally, a direct comparison will be made on two patients who have undergone both implant procedures.

Adolescent↗

PubMed1992

Frequency-specific auditory brainstem responses to bone-conducted stimuli.

The feasibility of recording bone-conducted auditory brainstem responses (ABRs) to 500-Hz and 2000-Hz tone bursts and clicks was investigated in normal-hearing adults. For all 3 stimuli, responses were detectable in all subjects at 30 dB nHL. At 20 dB nHL, the tone burst responses were detectable in 80-87% of the subjects, demonstrating that even the responses to 500-Hz tone bursts were relatively robust. Latencies and amplitudes of the responses were related to the stimuli. The cochlear locations contributing to the responses were investigated using high-pass masking. Derived-band analysis indicated reasonably good frequency specificity for the tone burst responses and a broad representation for the bone-conducted click, despite its lower frequency spectrum. The results of this study support the use of bone-conducted tone burst ABR for demonstrating frequency-specific normal cochlear sensitivity.

Acoustic Stimulation↗

PubMed1991

Masked high-frequency bone-conduction audiometry: test reliability.

The present study examines the reliability of masked high-frequency bone-conduction threshold measurements in 95 normal-hearing subjects. High-frequency pure-tone air-and bone-conduction thresholds were measured with a dedicated laboratory high-frequency auditory evaluation system using matched, modified Koss Pro/4X Plus earphones, and the Pracitronic KH 70/5 bone vibrator. A 400-Hz wide band masking noise centered at the frequency of the test tone was used to mask the nontest ear. Monaural masked bone-conduction threshold measurements were obtained at the ipsilateral mastoid of the ear with better high-frequency hearing. Two measurements were performed in each session, and each subject participated in two sessions. In several comparisons for test-retest consistency, high-frequency bone-conduction threshold measurements were as repeatable as air-conduction thresholds of identical frequency, or bone-conduction thresholds for frequencies of 4 kHz and less. High-frequency bone-conduction threshold measurement appears to be a sufficiently reliable tool for diagnosis of auditory disorders.

Adolescent↗

PubMed1989

[Prognostic value of the study of direct bone conduction in patients with otospongiosis].

The actual "early" improvement of hearing thresholds following stapedectomy were measured in 100 patients with otospongiosis by use of direct (intraoperative promontory bone stimulation) and conventional bone conduction audiometry prior to surgery. The direct bone conduction technique was usually more predictive in hearing improvement following stapedectomy than conventional bone conduction audiometry. The direct bone conduction seems to be a superior method for assessing hearing in patients with severe otospongiosis compared with conventional bone conduction which does not reflect actual cochlear reserve.

Audiometry, Pure-Tone↗

PubMed1976

Binaural masking effects in bone-conducted noise.

When pure tones are masked by bone-conducted noise presented at the midline of the forehead, it is possible that binaural unmasking may occur due to the interaural phase relations of the noise. To study this possibility, the amount of masking produced in bone-conducted noise, in correlated air-conducted noise, and in monaural noise was determined using narrow bands of noise centered at 240, 500, 910, and 1900 Hz as markers and a block up-down two-interval forced choice procedure. The subjects were four women under 30 years of age with 10 dB HTL or better (ANSI, 1969) for the frequencies tested. The amount of unmasking (the masking-level difference) was determined by subtracting the masking levels obtained under each noise condition at each frequency from those obtained in the comparable monaural noise-monaural signal condition. Levels of binaural unmasking obtained in correlated air-conducted noise agreed with those in previously reported experiments. Comparable binaural unmasking effects were demonstrated for midline presentation of bone-conducted noise. Some clinical implications of the findings are discussed.

Acoustic Stimulation↗

PubMed1990

Audiologic management of bilateral external auditory canal atresia with the bone conducting implantable hearing device.

The hearing impairment associated with congenital external auditory canal atresia has been managed with early bone conduction hearing aid placement and surgical reconstruction in selected patients. However, many patients do not wear a bone conduction hearing aid because of physical or social considerations and surgical reconstruction of the external auditory canal and middle ear may be difficult or contraindicated. This report details the use of implantable bone conducting hearing devices in five children with bilateral external auditory canal atresia. Each patient had bilateral conductive hearing impairment with normal bone conduction thresholds. Four of the five patients had associated craniofacial anomalies including three cases of microtia. The average preoperative sound field speech reception threshold improved from 63 dB to 13 dB with the implant. Patients experienced a definite preference for the implanted hearing device over the bone conduction hearing aid.

Adolescent↗

PubMed1992

Alterations of bone conducted hearing in cases of modified middle ear mechanics. Conclusions from an electrical model.

In clinical diagnosis bone conduction thresholds can be used to assess impaired hearing caused by pathological function of the inner ear. The effects of changed mechanical properties of the middle ear on bone conduction are usually not considered in patients who simultaneously suffer from middle ear and inner ear diseases. This procedure is only partially correct. An exact determination of the effects of altered middle ear mechanics on bone conduction in patients with otosclerosis or after middle ear operations is rather difficult, but such determinations can improve diagnostic validity. Therefore, a special electrical model was constructed to simulate the oscillation pattern of the basilar membrane for bone conduction and variable middle ear impedance. Results from the model and possible conclusions on bone conducted hearing in vivo are discussed. Further steps to ensure measurements of inner ear function in cases with modified middle ear mechanics are proposed.

Basilar Membrane↗

PubMed1989

Skull simulator for direct bone conduction hearing devices.

The Bone-Anchored Hearing Aid (BAHA) is a direct bone conduction hearing device which has given patients with various middle ear disorders a significantly improved quality of life. As the BAHA has gained acceptance as a valuable contribution to the Swedish hearing aid rehabilitation program, the need for equipment which can perform objective frequency response measurements has grown. Such equipment is indispensable for carrying out quality assurance, service, and fitting evaluation. To meet the above-mentioned demands, the skull simulator TU-1000 has been developed. The dynamic behaviour of the skull simulator TU-1000 can be characterized as that of a rigid mass body with a weight significantly exceeding the weight corresponding to the dynamic mass of the transducer incorporated in the BAHA. The motions of the mass body are measured by an accelerometer the output signal of which is amplified by a precalibrated amplifier. The output signal is proportional to the output force level from the BAHA. The skull simulator TU-1000 is capable of measuring the output force level from the BAHA with high reliability for frequencies ranging from 100 Hz to 10 kHz.

Biomechanical Phenomena↗