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At least 73 records · Page 4Linked to original sources
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↗
PubMed1998

Distortion product otoacoustic emissions stimulated through bone conduction.

OBJECTIVE: To demonstrate the viability of bone conduction as a novel method for stimulation of distortion product otoacoustic emissions (DPOAEs). DESIGN: DPOAEs were recorded from a single ear of 23 normally hearing adults using bone and air conduction for the delivery of stimulus tones. Exploration of the input-output function was performed by varying stimulus frequency and magnitude. RESULTS: Bone-stimulated emissions demonstrated similar characteristics to those obtained through standard air transmission techniques. Characteristic nonlinear DPOAE growth was found as the magnitude of the higher frequency stimulus tone, L2, was increased monotonically with other parameters fixed. Bilateral stimulation due to using bone conduction did not saturate the mechanisms of emission suppression. Emission magnitude was not altered substantially by occlusion of the ear canal. CONCLUSION: Bone conduction can be used successfully to elicit DPOAEs. Absolute comparison of air- and bone-stimulated DPOAEs was difficult because of imprecise calibration of the bone conductors for each individual and particular placement. Properties unique to bone conduction, such as simultaneous bilateral stimulation and reduction of stimulus magnitude in the ear canal, may make bone conduction attractive for clinical measurement of DPOAEs.

Acoustic Stimulation↗
PubMed2005

Bone-conduction hearing and the occlusion effect in otosclerosis and normal controls.

OBJECTIVE: The goal of this study was to better understand bone-conduction hearing in subjects with normal hearing and in those with otosclerosis through the occlusion effect. With this study, the authors hope to lend credence to commonly accepted theories of bone-conduction hearing and the effect of lateralization during the Weber tuning fork test. BACKGROUND: There are three accepted theories defining bone-conduction hearing: compressional bone conduction describes an auditory percept produced by the compression and expansion of the cochlea leading to basilar membrane vibration; inertial bone conduction describes the inertia of the ossicular chain as a result of skull vibration during bone conduction testing; whereas skull vibration may also be transmitted to the external auditory canal, surrounding soft tissues, and para-auditory structures to illicit tympanic membrane vibration known as osseotympanic bone conduction. METHODS: Twenty normal volunteers and 17 unilateral otosclerosis patients underwent external canal sound pressure level measurement during bone-conduction testing using a standardized bone oscillator placement and stimulation paradigm. Sound was detected with a probe microphone placed in the external auditory canal in nonoccluded and occluded conditions after a 50-dB hearing level bone-conduction stimulus. RESULTS: There was no significant difference in sound pressure level between otosclerosis and normal subjects when the external auditory canals were nonoccluded. With occlusion, sound pressure level increased in both groups, but at a statistically significantly higher level for the otosclerosis group. CONCLUSION: Sound measured in the external canal likely represents energy lost to the environment transmitted through the middle and external ear systems, aided by the effect of both inertial and osseotympanic bone conduction. Occluding the ear leads to sound trapping and amplification. Also, the pressure exerted against the tympanic membrane reduces middle ear compliance and increases the impedance mismatch between air and the middle ear system, reflecting sound back into the external canal. This effect is further enhanced by stapes fixation to explain our data in both groups of subjects. The final common pathway in "lateralization" is probably a product of higher than normal impedance mismatch at the oval window.

Auditory Threshold↗
PubMedDate not supplied

[Bone conduction auditory brainstem responses in normal hearing individuals].

BACKGROUND: bone conduction auditory brainstem responses (ABR) in normal hearing individuals. AIM: to evaluate the clinical applicability of bone conduction ABR, characterizing normality and determining an assessment protocol. METHOD: participants of this study were 22 individuals with normal hearing (20dB NA), with ages between 20 and 30 years, 14 female and 8 male. All individuals were assessed using air and bone (vibrator positioned on the forehead and mastoid) conduction ABR. EP25 equipment, Interacoustic; 3A insertion phone; B-71 bone vibrator; click stimulus. RESULTS: it was possible to evaluate the bone conduction ABR in all individuals. The results demonstrate that the electrophysiological threshold obtained when the vibrator was positioned on the forehead (32.69+/-5.63 and 32.5+/-7.07dB nHL) was higher than that obtained when the vibrator was positioned on the mastoid (25.00+/-7.33 and 30.00+/-5.34dB nHL) for both genders respectively. For this reason the vibrator was positioned on the mastoid. The electrophysiological threshold obtained by bone conduction was higher than that obtained by air conduction for both genders and also when all individuals were grouped together. Thus it is necessary to use a correction factor, according to the results, of 10dB nHL. The latency-intensity values of the V wave in the ipsilateral and contralateral recordings differed statistically according to gender, and should be considered separately. The value of 26.81+/-6.99dB nHL was adopted as being the normal threshold for bone conduction ABR. CONCLUSION: it is possible to evaluate bone conduction ABR in the clinical environment. These results, when considered along with the air conduction ABR, increase the chances of a more precise diagnosis regarding the type of hearing loss.

Adult↗
PubMed2007

Effects of bone oscillator coupling method, placement location, and occlusion on bone-conduction auditory steady-state responses in infants.

OBJECTIVE: The aim of these experiments was to investigate procedures used when estimating bone-conduction thresholds in infants. The objectives were: (i) to investigate the variability in force applied using two common bone-oscillator coupling methods and to determine whether coupling method affects threshold estimation, (ii) to examine effects of bone-oscillator placement on bone-conduction ASSR thresholds, and (iii) to determine whether the occlusion effect is present in infants by comparing bone-conduction ASSR thresholds for unoccluded and occluded ears. DESIGN: Experiment 1A: The variability in the amount of force applied to the bone oscillator by trained assistants (n = 4) for elastic-band and hand-held coupling methods was measured. Experiment 1B: Bone-conduction behavioral thresholds in 10 adults were compared for two coupling methods. Experiment 1C: ASSR thresholds and amplitudes to multiple bone-conduction stimuli were compared in 10 infants (mean age: 17 wk) using two coupling methods. Experiment 2: Bone-conduction ASSR thresholds and amplitudes were compared for temporal, mastoid and forehead oscillator placements in 15 preterm infants (mean age: 35 wk postconceptual age (PCA)). Experiment 3: Bone-conduction ASSR thresholds, amplitudes and phase delays were compared in 13 infants (mean age: 15 wk) for an unoccluded and occluded test ear. All infants that participated had passed a hearing screening test. RESULTS: Experiment 1A: Coupling method did not significantly affect the variability in force applied to the oscillator. Experiment 1B: There were no differences in adult bone-conduction behavioural thresholds between coupling methods. Experiment 1C: There was no significant difference between oscillator coupling method or significant frequency x coupling method interaction for ASSR thresholds or amplitudes in the young infants tested. However, there was a nonsignificant 9-dB better threshold at 4000 Hz for the elastic-band method. Experiment 2: Mean bone-conduction ASSR thresholds for the preterm infants were not significantly different for the temporal and mastoid placements. Mean ASSR thresholds for the forehead placement were significantly higher compared to the other two placements (12-18 dB higher on average). Mean ASSR amplitudes were significantly larger for the temporal and mastoid placements compared to the forehead placement. Experiment 3: There was no difference in mean ASSR thresholds, amplitudes or phase delays for the unoccluded versus occluded conditions. CONCLUSIONS: Trained assistants can apply an appropriate amount of force to the bone oscillator using either the elastic-band or hand-held method. Coupling method has no significant effect on estimation of bone-conduction thresholds; therefore, either may be used clinically provided assistants are appropriately trained. For preterm infants, there are no differences in ASSRs when the oscillator is positioned at the temporal or mastoid placement. However, thresholds are higher and amplitudes are smaller for the forehead placement, consequently, a forehead placement should be avoided for clinical testing. There does not appear to be a significant occlusion effect in young infants; therefore, it may be possible to do bone-conduction testing with ears unoccluded or occluded without applying a correction factor, although further research is needed to confirm this finding.

Acoustic Stimulation↗
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↗
PubMed2005

Multiple auditory steady-state responses to bone-conduction stimuli in adults with normal hearing.

ASSR thresholds to bone-conduction stimuli were determined in 10 adults with normal hearing using mastoid placement of the bone oscillator. ASSRs to 0-50 dB HL bone-conduction stimuli and to 30-60 dB HL air-conduction stimuli were compared. The effect of alternating stimulus polarity on air- and bone-conduction ASSRs was also investigated. Stimuli were bone- and air-conduction amplitude-modulated tones (500-4000 Hz carrier frequencies, modulated at 77-101 Hz). ASSRs were recorded using the Rotman MASTER research system. Mean (1SD) bone-conduction ASSR thresholds were 22(11), 26(13), 18(8), and 18(11) dB HL for 500, 1000, 2000, and 4000 Hz, respectively. Except for a steeper slope at 500 Hz, ASSR intensity-amplitude functions for binaural bone- and air-conduction stimuli showed the same slopes; intensity-phase-delay functions were steeper at 1000 Hz for ASSRs to bone-conduction stimuli. ASSR amplitudes and phases did not differ for single- versus alternated-stimulus polarities for both bone- and air-conduction stimuli. The steeper amplitude slope for ASSRs to 500 Hz stimuli may reflect a nonauditory contribution to the ASSR.

Adult↗
PubMed1994

Carhart notch and electric bone-conduction audiometry.

The Carhart notch is a depression in the bone-conduction audiogram of patients with clinical otosclerosis. The middle frequencies from 0.5 to 2 kHz, which correspond to the resonance frequency of the middle ear, can be substantially improved following successful stapes surgery. Twenty-nine consecutive patients with clinical otosclerosis were tested 2 weeks before and 7 months after stapes surgery with conventional air-conduction (AC) and bone-conduction (BC) audiometry and electric bone-conduction (EBC) audiometry using an Audimax 500 audiometer. The BC thresholds improved at 0.5-2.0 kHz corresponding to the Carhart notch. On average, the EBC thresholds remained more stable, showing no Carhart phenomenon, which supports the concept that EBC stimulation is not entirely equivalent to conventional BC audiometry, but has a different mode of action on the inner ear.

Adult↗
PubMedDate not supplied

Lateralization of bone-conducted sounds.

Lateralization of bilaterally applied bone-conducted signals could be accomplished by variation of time (delta t) or intensity (delta I) differences between signals. The task was relatively easy with clicks and with tone pips with short rise times. When rise times were made longer than 1 msec the ability to localize deteriorated, indicating that it depended, within limits, on the steepness of the signal wavefront. Consequently, localization of continuous, pure-tone signals was much more difficult. It improved, with training, after subjects noticed small loudness increments on the side of the leading signal as soon as the phase between signals (delta phi) deviated from zero. Thus, localization of pure-tone signals was aided both by delta phi and delta I. The loudness increments were found to be caused by mechanical interference of ipsi- and contralateral signals at each cochlea, a type of interference peculiar to bone-conducted signals. There were also indications of slight degrees of neural interaction (mutual masking) so long as delta t between short-lasting signals was near zero. The tactile input at the point of contact between vibrators and skin did not significantly contribute to lateralization of bone-conducted signals.

Audiometry, Pure-Tone↗
PubMed1987

Repeatability of high-frequency bone conduction thresholds.

The purpose of this study was to determine the repeatability of high-frequency, bone conduction thresholds and to increase the data base concerning high-frequency, bone conduction threshold levels. Bone conduction thresholds were obtained on 30 subjects having normal, low, and mid frequency (0.25 to 8 kHz) hearing thresholds within and across five test sessions using a Pracitronic KH 70 bone vibrator referenced to a Brüel and Kjaer 4930 mechanical coupler at 1, 4, 8, 10, 12, 14, and 16 kHz. Within and across sessions, the bone conduction thresholds were not significantly (p greater than 0.05) different at each frequency indicating that repeated testing without replacing the bone vibrator (within session) and with replacing the bone vibrator (across session) did not influence the threshold measurements. Clinical implications concerning high-frequency, bone conduction audiometry are discussed.

Adult↗
PubMed2000

Bone conduction experiments in animals - evidence for a non-osseous mechanism.

Bone conducted stimuli are used to differentiate between conductive and sensori-neural hearing loss. It has been thought that the main route for the transfer of vibratory energy from the point of application of the bone vibrator on the skull to the inner ear is completely osseous. An additional mechanism may play a prominent role. In rats, a bone vibrator was applied to the skull and also directly on the brain, after removing bone (a craniotomy), exposing the brain. Auditory nerve-brainstem evoked response (ABR) could be elicited not only with the vibrator on bone, but also with the vibrator directly on the brain. Similar results were obtained in guinea-pigs and fat sand rats. Noise masked this ABR. Extensive removal of skull bone did not alter the ABR to bone-conducted stimuli delivered to the exposed brain. Experimental elimination of the ossicular chain inertial mechanism and of the occlusion effect did not greatly alter the bone conduction response. A reduction in the fluid volume of the cranial cavity induced threshold elevations of the bone conducted ABR but not of the air conducted ABR. These findings can be interpreted as evidence that the 'classical' bone conduction mechanisms should be modified to include a major pathway for cochlear excitation which is non-osseous: when a bone vibrator is applied to the skull, the bone vibrations may induce audio-frequency sound pressures in the skull contents (brain and cerebro-spinal fluid) which are then communicated by fluid channels to the fluids of the inner ear.

Animals↗
PubMed2002

Air versus bone conduction: an equal loudness investigation.

Air conduction (AC) versus bone conduction (BC) loudness balance testing was conducted at frequencies of 0.25, 0.5, 0.75, 1, 2, and 4 kHz for two groups: 23 normal hearing subjects and eight subjects with a mild to moderate pure sensorineural hearing loss. Narrow-band noise was presented interchangeably between earphones and a bone transducer fitted to the subjects. Loudness matching was carried out at each frequency and at the levels 30-80 dB hearing level (HL) (10 dB steps) in the following manner: the sound pressure from the earphones was fixed and the subject adjusted the output level of the bone transducer for equal loudness by bracketing the standard. The results revealed somewhat different loudness functions for AC and BC sound with a 6-10 dB difference in the AC and BC loudness functions for the normal hearing group over the dynamic range 30-80 dB HL at the frequencies 250-750 Hz. At the higher frequencies, 1-4 kHz, the difference was only 4-5 dB over the same dynamic range. Similar results were obtained for the sensorineural hearing-impaired group. The difference between the AC and the BC loudness functions may originate from changes with level of the AC sound path, e.g. contraction of the stapedius muscle, but also distortion from the bone transducer and tactile stimulation could have contributed to the results seen.

Acoustic Stimulation↗
PubMed1988

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↗
PubMed1993

Auditory brainstem response thresholds to air and bone conducted clicks in neonates and adults.

Auditory brainstem response (ABR) thresholds to air and bone conducted clicks were investigated in 20 full-term neonates and 20 normal-hearing young adults. Results showed mean ABR thresholds to air and bone conducted clicks for neonates to be 3.75 dB nHL (40.75 peak SPL) and 1.25 dB nHL (36.25 dB peak re: 1 microN), respectively, and for adults 3.75 dB nHL (40.75 peak SPL) and 18.75 dB nHL (53.75 peak re: 1 microN), respectively. A significant difference was observed in mean ABR thresholds to bone conducted stimuli between neonates and adults (p < 0.0001) and among mean adult ABR thresholds to air and bone conducted stimuli (p < 0.0001). Nonsignificant differences were observed in mean ABR thresholds to air and bone conducted stimuli among neonates (p > 0.05) and in mean ABR thresholds to air conducted stimuli between neonates and adults (p = 1.00). It is speculated that the dissimilarity in the relationship of thresholds to air and bone conducted stimuli between neonates and adults reflects, in part, a difference in efficiency of signal delivery to the cochlea.

Acoustic Stimulation↗
PubMed1995

Assessment of bone conduction prosthesis in situ.

Conventional and bone anchored bone conduction hearing aids can be tested with skull simulating devices and the individual adjustment rely on time consuming psychoacoustic audiometry in free-field which can be quite demanding for the patient. A method is presented in which the hearing aid induced skull vibrations are collected with an acceleromotor and recorded on a digital audio tape. The recordings are analysed with Fast Fourier 'Transformation (FFT) by using a signal processor. The free-field test signal can be either narrow-band or white noise. Changes in frequency characteristics can be easily monitored with white noise as signal, harmonic distortion and dynamic response can be analysed reliably by using pure tones. The inter-individual comparisons can be made when calibration is based on skull vibrations at the individual bone-conduction hearing thresholds. Two case reports are presented and discussed.

Adult↗
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↗
PubMedDate not supplied

Air and bone conduction brain stem responses in adults and infants.

Air and bone conduction brain stem responses were recorded in 20 adults and 20 infants (16-20 months postconceptional age) with normal hearing. The stimuli were administered using a shielded TDH-39 headphone and a standard B-70A vibrator. Our results show that adults and infants have similar air and bone conduction brain stem thresholds. The comparison of input latency functions obtained with air and bone conduction clicks indicates that the acoustic stimulus generated by the bone vibrator excites more apical regions than that stimulated by the air conduction transient. This is related to the spectrum of the bone conduction click which has an energy peak at 1-2 kHz. Furthermore we found that the difference in latency between adults and infants for air-conducted clicks decreases along with the stimulus intensity and the latencies tend to overlap near the threshold.

Adult↗