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PubMed1993

Auditory brain stem responses to air- and bone-conducted clicks in the audiological assessment of at-risk infants.

Auditory brain stem responses (ABRs) to air- and bone-conducted clicks were used to assess the auditory status of 170 at-risk neonates. During the perinatal period, 20.6% (35/170 cases) of the at-risk infants failed ABRs to air-conducted clicks at 30 dB nHL in at least one ear. Ear-specific results indicated an initial failure rate of 15.0% (51/340 ears). Approximately two-thirds (32/51 ears) of these initial failures showed purely conductive deficits, whereas the remaining one-third (19/51 ears) involved suspected sensorineural components. Follow-up audiological evaluations were performed for 87.1% (148 cases) of these at-risk infants at 4 mo and/or 1 yr corrected age. Based on the initial tests and follow-up assessments, the tentative operating characteristics of ABRs to both air- and bone-conducted clicks for identification of sensorineural deficits in at-risk neonates were calculated. It was found that the ABR to bone-conducted clicks yielded better specificity, predictive value of positive results, and overall efficiency. It is suggested that the ABR to bone-conducted stimuli should be viewed as a valuable addition in the assessment of cochlear reserve in infants who fail a newborn auditory screening to air-conducted stimuli.

Acoustic Stimulation↗
PubMed1992

[Masking in bone-conduction testing--proposal of ABC method].

A new strategic masking technique, namely the ABC method, has been developed. In performing this method of measuring thresholds of bone-conduction, the vibrator is placed at the forehead with both ears occluded by air-conduction earphones. One of the earphones is for masking noise and the other is a dummy which balances out the occlusive effect of the test ear against the nontest ear. The ABC method is based on the ABC rule that, in bone-conduction testing, the effective masking noise level necessary to block out the nontest ear can be calculated by a simple equation: right AC (A) + left AC (B)--unmasked BCu (C) under the assumption that the BCu belongs to the nontest ear. In some cases of hearing loss, the above noise level might produce overmasking, then an additive safety noise level, BCu + Interaural Attenuation, is employed. This method offers testers step by step directions which consist of indications of the noise level and a criterion for determining whether the measured bone-conduction is free from cross hearing and overmasking for the given configuration of air-conduction of both ears, BCu, and the masking noise level. Compared to the well known Plato method, in which measurements of thresholds are repeated at several masking noise levels in order to find a single bone-conduction threshold, the ABC method can essentially find the threshold at only one masking noise level. Therefore the ABC method makes it possible to save a great deal of time in performing bone conduction testing.

Audiometry↗
PubMed2002

Soft tissue movement and stress shielding do not affect bone ingrowth in the bone conduction chamber.

A variety of bone chambers are used in orthopedic research to study bone and tissue ingrowth in small and large animals. If different bone chambers are placed in one species, differences in bone ingrowth are observed. For instance, bone ingrowth in the bone conduction chamber (BCC) is high, but is low or absent in the repeated sampling bone chamber (RSBC). This difference may be explained by the design and fixation of these chambers. It is known that stress shielding and micromovement can influence bone formation. The objective of the study reported here was to determine whether stress shielding or soft tissue movement affected bone ingrowth in the BCC in the goat. Two types of caps were made, with fixation similar to that of the fixation plate of the RSBC. By placing the caps over the BCCs and fixating the caps directly to the tibial bone, the effect of stress shielding was studied. One cap was in direct contact with the bone chamber underneath, the other cap did not touch the chamber. This difference was used to observe whether movement of the soft tissue on top of the chamber and cap would affect bone ingrowth. Each limb received one control chamber without a cap and a chamber with a cap, either with or without contacting the BCC, yielding four implants per goat. After 12 weeks, bone and total tissue ingrowths were measured. Bone ingrowth was seen in 38 of 40 chambers. Total tissue and bone ingrowths were comparable between control chambers and BCCs with a cap, irrespective of type. Neither stress shielding, nor lack of movement of soft tissue affected bone ingrowth. Other factors in the design of the chambers were responsible for the difference in bone ingrowth between the BCC and the RSBC.

Animals↗
PubMedDate not supplied

Confirmation of G. von Békésy's theory of paradoxical wave propagation along the cochlear partition by means of bone-conducted auditory brainstem responses.

In order to investigate the propagation time of the traveling wave in the cochlea after bone-conduction stimulation of the inner ear, bone-conducted auditory brainstem responses (ABRs) were recorded in 6 normally hearing subjects after masking the basal cochlear region using high-pass filtered noise. As in air-conducted ABRs, Jewett V wave latency is delayed corresponding to the propagation time of the traveling wave front traversing the desynchronized hair cell region. These results support the theory of paradoxical wave propagation proposed by von Békésy in 1952, who postulated that wave motion always starts from the stiffest part of the basilar membrane, independent of the location of the vibrating force. In addition, we also found a latency delay of the Jewett V wave of bone-conducted ABRs in 8 patients with high-frequency hearing loss which corresponded to the severity of their hearing impairment.

Adolescent↗
PubMed1982

Reliability of bone-conducted electrocochleography. A clinical study.

The correlation between pure-tone bone conduction thresholds (BC) and thresholds obtained by electrocochleography with bone conducted stimulation (BC-ECoG) for 1, 2, 4 and 8 kHz was studied in 26 ears due for ear surgery. The correlations proved to be statistically highly significant and the results lend support to the conclusion that BC-ECoG can be considered to be well adapted for clinical use in cases where conventional audiometry has failed to reveal the capacity of the cochlea.

Audiometry↗
PubMed1998

Air- and bone-conduction brainstem auditory evoked potentials and flash visual evoked potentials in cats.

OBJECTIVE: To document normal values for air- and bone-conducted brainstem auditory evoked potentials (BAEP) and for flash visual evoked potentials (VEP) in cats. ANIMALS: 10 mixed-breed cats (5 males) with normal physical, neurologic, otoscopic, and funduscopic examination results. PROCEDURE: BAEP in response to air- and bone-conducted click stimuli and VEP in response to flash stimuli were recorded to document species normative data. Mean and SD values were calculated for amplitudes and latencies of 4 peaks in the BAEP in response to air- and bone-conducted stimuli, and for latencies to 5 peaks and the 4 associated peak-to-peak amplitudes in the VEP. RESULTS: BAEP peak latencies increased and peak amplitudes decreased with decreasing stimulus intensity. Latencies were shorter for bone-conducted stimuli owing to the shorter transit time to the cochlea through bone, compared with air, but there were no differences for interpeak latencies. The BAEP and VEP recordings were similar to those reported for cats in other reports and were similar to those seen in other species. CLINICAL RELEVANCE: Normative data will permit performance of noninvasive electrodiagnostic evaluation of feline auditory and visual systems.

Acoustic Stimulation↗
PubMed1977

[Bone conduction changes in secretory otitis media (author's transl)].

In serous and secretory otitis media a reduction of bone conduction frequently exists besides the loss of air conduction. In 304 audiograms of ears with serous and viscous fluid in the middle ear there was a depression of the bone conduction between 15 and 40 dB in 40%. This bone conduction loss was reversible after the aeration of the tympanic cavity. That means that we deal with a false nerve deafness in many of these cases.

Bone Conduction↗
PubMed1992

High-frequency audiometry. Masking in electric bone-conduction audiometry.

Recently, the 'electric bone-conduction' (EBC) audiometer (Audimax 500) has been used to measure high-frequency (HF) hearing. With this audiometer stimulation is binaural. No commercial masking method was available. In this study, white noise from a Madsen OB822 audiometer and presented via Sony MDR-V4 dynamic earphones, was used for masking. The masking and cross-hearing effect was measured in 8 unilaterally deaf subjects and the masking procedure was tested with 104 young normal-hearing subjects. The results showed that the EBC signals can be masked with air-conduction signals, and thus, the EBC measurements reflect monaural thresholds. The minimum masking level was 50-60 dB SPL in the HF range. There were no cross-hearing problems in the HF range with the earphones used. At the frequencies 0.5-14 kHz, the better ear's masked EBC thresholds were on the average 2.6 dB (range 0-4.5 dB) poorer, compared with the binaural EBC thresholds, indicating a binaural summation effect.

Acoustic Stimulation↗
PubMed1989

Validity of bone conduction stimulated ABR, MLR and otoacoustic emissions.

The present study considers the validity of objective auditory investigation via bone conduction. Auditory Brainstem Responses (ABR) and Middle Latency Responses (MLR) were recorded in response to a bone vibrator stimulation with or without continuous bilateral air white noise masking. In all cases, such masking was found to result in an absence of recorded evoked potentials. It shows that under bone-conducted stimulation the evoked potential recorded is purely auditory, with no additional mechanical somatosensory component. In a further study, the feasibility of oto-acoustic emissions (OAEs) via bone conduction is demonstrated. These OAEs are, for a given subject, comparable to those found for air-transmission stimulation.

Adolescent↗
PubMedDate not supplied

A comparative study of alternative bone-conduction calibration methods.

The accepted instrument for calibrating the bone-conduction section of an audiometer is the artificial mastoid. For a variety of reasons, alternative calibration methods are in general use. Three common methods are: (1) the input voltage method; (2) the real-ear threshold method using normal-hearing listeners; and (3) the real-ear threshold method using subjects with sensorineural hearing loss. The present investigation compared these methods for both accuracy and efficiency. There were no significant differences in accuracy found among the three calibration methods. Substantial differences in efficiency were noted, however. When accuracy and efficiency are considered, the input voltage method appears to be the best alternative method for calibrating the bone-conduction system of an audiometer.

Adolescent↗
PubMed2002

Effect of stimulus duration for bone-conducted ultrasound on N1m in man.

Ultrasound can be heard by bone conduction in man. However, there has been no consensus about the perception mechanism of bone-conducted ultrasound (BCU). In the current study, to clarify the central auditory system of BCU, the effects of stimulus duration for 30 kHz BCU on N1m were compared with those for air-conducted 1 kHz tone bursts by magnetoencephalography. As a result, the growth of N1m amplitude for both stimuli saturated at the duration of 40 ms, which suggest that the temporal integration system of BCU is similar to that of audible sound. However, significant differences in the growth were observed below the saturation points. The results indicate a possibility that there are some differences in the central auditory system between BCU and audible sound.

Acoustic Stimulation↗
PubMed2002

Sound stimulation via bone conduction for tinnitus relief: a pilot study.

For some patients suffering from tinnitus, an external sound stimulator can offer some mitigation. Based on our positive experience with the bone-anchored hearing aid (BAHA), it seems possible to transmit a masking or habituating sound via bone conduction. A potential advantage of bone-conducted sound is that it is transmitted to the cochlea without affecting the normal hearing via the external and middle ear. The present pilot study, on patients who use a conventional BAHA and who experience mild-to-moderate tinnitus, shows that bone-conducted sound has the potential to relieve tinnitus in the same way as air-conducted sound. It was also found that these patients, having a significant conduction hearing loss, required conventional sound amplification via a BAHA simultaneously with the stimulus provided by the bone-anchored sound stimulator (BASS). Further studies on patients with more severe tinnitus must be conducted in order to justify the use of a BASS for tinnitus relief.

Acoustic Stimulation↗
PubMedDate not supplied

Bone-conduction masking for threshold assessment in auditory brain stem response testing.

The viability of applying Sensorineural Acuity Level (SAL) audiometry to auditory brain stem response (ABR) testing was investigated using 38 subjects with normal hearing, conductive, sensorineural, and mixed hearing losses. The stimuli were clicks, 4000, 2000, and 1000 Hz tone-pips. After ABR thresholds (ABRt) were obtained, bone-conducted noise was used to mask the response to a stimulus 5 dB above ABR threshold (ABRt + 5). Estimates of behavioral bone-conduction thresholds were made by observing the amount of noise needed to mask ABRt + 5. Estimates of behavioral air-conduction thresholds were based upon ABRt. Results indicated that ABRt was within +/- 10 dB of behavioral air-conduction threshold across subject groups at least 74% of the time for all tone-pip stimuli. ABRt was within +/- 15 dB of the pure-tone average of 1000, 2000, and 4000 Hz 75% of the time when click stimuli were used. Derived bone-conduction thresholds were within +/- 10 dB of the actual bone-conduction threshold at least 73% of the time for all stimuli. It was concluded that, when used in a conservative manner, the application of SAL audiometry to ABR testing may increase the reliability and confidence with which decisions are made concerning the type and degree of hearing loss in difficult-to-test patients.

Adult↗
PubMed1978

Physical and physiological constraints on the use of bone-conduction speech audiometry.

Several authors have recommended the use of bone-conduction speech audiometry, and the literature supports the clinical value of this procedure. It has been claimed that bone-conduction output for speech can be increased to 110-dB HL with the Radioear B-70-A vibrator through supplementary amplification, but this claim is unsubstantiated by objective measurements. Available technical data indicate that the maximum output level attainable with this virbator without incurring serious distortion is 65- to 70-dB HL at midfrequencies and substantially less at lower frequencies. Both behavioral and electromechanical data are presented which show, not only that 70-dB HL is the absolute maximum hearing level for speech attainable through the B-70-A vibrator without serious deterioration of speech-discrimination scores in normal listeners, but also that this appears to be very close to the maximum vibratory level that human observers can comfortably tolerate.

Audiometry↗
PubMed1986

The use of acoustical test fixtures for the measurement of hearing protector attenuation. Part II: Modeling the external ear, simulating bone conduction, and comparing test fixture and real-ear data.

This paper investigates two main features of the human head which influence the measured attenuation of circumaural and intraaural hearing protection devices (HPDs): the external ear and the different pathways of bone conduction. A theoretical model for the external ear shows that its influence on the insertion loss of HPDs, on the sensitivity level of headphones or earphones, and on the insertion gain of hearing aids, all can be described by one equation. While it is not necessary to simulate the eardrum impedance in order to measure the insertion loss of earmuffs and the sensitivity level of headphones with acoustical test fixtures (ATFs), the required accuracy of an ear simulator is more stringent when the same measurements are performed on intraaural devices. For the evaluation of HPDs, bone conduction plays an important role. We have developed a model to estimate HPD-dependent bone conduction effects. The model includes two bone conduction sources: one in the external ear and one in the middle ear. The model explains, for example, the occlusion effect of HPDs and the masking error at low frequencies due to physiological noise that arises when real-ear attenuation at threshold (REAT) measurements are made. Consequently, objectively measured insertion loss can now be used to predict REAT with improved accuracy. ATF and REAT data are compared using nine earmuffs and nine earplugs. In the majority of cases, the two sets of data agree well. Discrepancies are discussed.

Auditory Threshold↗
PubMedDate not supplied

The middle ear inertial component of bone-conduction hearing in man.

The middle ear inertial component of bone-conduction hearing was studied in 8 normal-hearing young adults. The inertial component was eliminated to varying degrees by introducing various positive and negative air pressures into the ear canal. Sweep-frequency Békésy tracings were obtained from 100 through 5 000 Hz for bone-conducted pure tone stimuli while the air pressure of the test ear was varied and the nontest ear was masked. Air pressures of +/- 100, +/- 300, and +/- 500 mm H2O were utilized. Results revealed maximal shift in the mid frequencies (750 Hz) and an increase in effect with increase in pressure. A second prominent region of threshold shift emerged at 2 000 Hz for the +/- 500 mm H2O air pressure conditions. Considerable variability in the magnitude of threshold shift and in the frequency region of maximum shift was observed.

Acoustic Stimulation↗
PubMed1994

Myringoplasty. A conventional and extended high-frequency, air- and bone-conduction audiometric study.

Comparison of the pre- and postoperative air- and bone-conduction thresholds in 22 subjects in whom successful myringoplasty was performed has been made in the conventional and extended high-frequency ranges. Air-conduction thresholds improved through 4 kHz, but were elevated postoperatively for the frequencies 6 through 18 kHz. Postoperative bone-conduction thresholds were elevated at 0.25 and 0.5 kHz, were lower by 2-8 dB for 1 through 3 kHz and not significantly altered in the extended high-frequency range of 8 through 16 kHz. The extended high-frequency air-conduction threshold loss following myringoplasty in this study is, therefore, due to changes in middle ear transmission and is not indicative of iatrogenic cochlear damage.

Acoustic Stimulation↗
PubMed1992

Hearing with the bone-anchored hearing aid (BAHA, HC 200) compared to a conventional bone-conduction hearing aid.

Sixteen patients have been fitted with a standard bone-anchored hearing aid (HC 200), to replace their conventional bone-conduction aid. The average pure tone threshold at 0.5, 1 and 2 kHz varied from 35 to 75 dB HL, with a sensorineural component varying from 0 to 30 dB HL. The patients' performance with the bone-anchored aid was compared to that with the conventional bone-conduction aid in an acoustic-free field. The maximum phoneme score in quiet was 100% in most patients; in 6 patients, the score with the bone-anchored aid was better (range from 5 to 10%). The speech-in-noise ratio was significantly better in 11 patients (range from -1.4 to -8 dB). None of the patients had poorer results on either test with the bone-anchored aid. The improved speech recognition was ascribed to better performance of the hearing aid in the higher frequency range (above 2 kHz) and to relatively less distortion.

Adolescent↗