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PubMed2001

Carhart notch effect in otosclerotic ears measured by electric bone-conduction audiometry.

The Carhart notch is an elevation in the middle-frequency bone-conduction threshold of an ear with clinical otosclerosis. The study population consisted of 138 patients with clinical otosclerosis. Conventional air-conduction (AC) and bone-conduction (BC) and electric bone-conduction (EBC, with Audimax 500 audiometer) thresholds were measured 2 weeks before and 7 months after stapes surgery. The EBC thresholds were converted from mA values to dB SPL to compare the results obtained with the different methods. The mean differences in the BC thresholds before and after the operation were 3.2 dB (95% CI 1.9-4.6) at 1 kHz and 7.6 dB (95% CI 6.1-9.1) at 2 kHz. The mean differences in the EBC thresholds were 5.4 dB (95% CI 3.8-6.9) at 1 kHz and 5.3 dB (95% CI 3.4-7.1) at 2 kHz. Thus, both methods showed a distinct Carhart notch effect.

Audiometry, Pure-Tone↗
PubMed1995

Objective real ear measurements of bone-conduction hearing aid performance.

Conventional bone-conduction and bone-anchored hearing aids are tested with skull simulator devices; individual adjustments are reliant on psychoacoustic free-field audiometry, which can be quite demanding for the patient. A method is presented in which the induced skull vibrations are measured with an accelerometer and then analysed with Fast Fourier Transformation (FFT). With this method, frequency characteristics, harmonic distortion and dynamic response can be analysed.

Bone Conduction↗
PubMed2003

Vestibular activation by bone conducted sound.

OBJECTIVE: To examine the properties and potential clinical uses of myogenic potentials to bone conducted sound. METHODS: Myogenic potentials were recorded from normal volunteers, using bone conducted tone bursts of 7 ms duration and 250-2000 Hz frequencies delivered over the mastoid processes by a B 71 clinical bone vibrator. Biphasic positive-negative (p1n1) responses were recorded from both sternocleidomastoid (SCM) muscles using averaged unrectified EMG. The best location for stimulus delivery, optimum stimulus frequency, stimulus thresholds, and the effect of aging on evoked response amplitudes and thresholds were systematically examined. Subjects with specific lesions were studied. Vestibular evoked myogenic potentials (VEMP) to air conducted 0.1 ms clicks, 7 ms/250-2000 Hz tones, and forehead taps were measured for comparison. RESULTS: Bone conducted sound evoked short latency p1n1 responses in both SCM muscles. Ipsilateral responses occurred earlier and were usually larger. Mean (SD) p1 and n1 latencies were 13.6 (1.8) and 22.3 (1.2) ms ipsilaterally and 14.9 (2.1) and 23.7 (2.7) ms contralaterally. Stimuli of 250 Hz delivered over the mastoid process, posterosuperior to the external acoustic meatus, yielded the largest amplitude responses. Like VEMP in response to air conducted clicks and tones, p1n1 responses were absent ipsilaterally in subjects with selective vestibular neurectomy and preserved in those with severe sensorineural hearing loss. However, p1n1 responses were preserved in conductive hearing loss, whereas VEMP to air conducted sound were abolished or attenuated. Bone conducted response thresholds were 97.5 (3.9) dB SPL/30.5 dB HL, significantly lower than thresholds to air conducted clicks (131.7 (4.9) dB SPL/86.7 dB HL) and tones (114.0 (5.3) dB SPL/106 dB HL). CONCLUSIONS: Bone conducted sound evokes p1n1 responses (bone conducted VEMP) which are a useful measure of vestibular function, especially in the presence of conductive hearing loss. For a given perceptual intensity, bone conducted sound activates the vestibular apparatus more effectively than air conducted sound.

Adult↗
PubMed1987

Bone conduction masking for brainstem auditory-evoked potentials (BAEP) in pediatric audiological evaluations. Validation of the test.

A brainstem auditory-evoked potential (BAEP) protocol for testing pediatric patients at risk for conductive hearing impairment was evaluated. The protocol used was: air-conducted click stimuli masked by bone-conducted wide-band noise. The specificity and sensitivity values for the test were determined by means of a blind cross-sectional trial including an active group of patients with an aural malformation and an age-matched control group with a sensorineural impairment. The bone-conducted masking of air-conducted BAEP showed high specificity and sensitivity and was easily administered despite pediatric difficulty. It was useful in differentiating sensorineural from conductive impairment and provided a rough estimate of the cochlear reserve in presumptive conductive hearing loss as great as 60 dB hearing loss. It is concluded that the bone-conducted masking procedure appears to be a great help in the binary decision whether middle ear surgery should be performed in patients at risk for conductive hearing loss, specially children with aural malformations.

Adolescent↗
PubMed1997

[Bone conduction hearing aids with fluid medium].

In patients with chronic otorrhoea or middle ear pathology, traditional hearing aids which depend on air conduction are of little use. In these situations a bone conduction hearing aid is preferable. Such devices by-pass the middle ear cleft and ossicular chain by conducting sound waves through bone to the cochlea. To date, bone conduction hearing aids have transmitted sound via a vibrating transducer applied either to skin (transcutaneous) or to bone (percutaneous). Unfortunately, these hearing aids possess a number of disadvantages, which include: cost, aesthetic appeal, a general anaesthetic for percutaneous aids, and most notably pressure discomfort to the side of the head. To overcome some of these problems a new bone conducting hearing aid is being developed which differs from conventional aids in that sound transmission is through a liquid medium. This has been tentatively named the "Hydro-Hearing Aid" and a prototype is now being tested.

Adult↗
PubMed2002

Bone conduction hearing on the teeth of the lower jaw.

Bone conduction stimulation of the teeth of the lower jaw initiates auditory sensations. However the lower jaw is only loosely coupled to the skull by the temporo-mandibular joint. Therefore the 'classical' bone conduction pathway involving skull vibration transmission entirely along bone to the temporal-petrous bone requires further consideration. Bone conduction hearing thresholds to stimulation at the forehead and at the teeth of the upper and lower jaw were determined in human subjects. Thresholds on the teeth were better than those on the forehead and there was no difference between the thresholds measured following stimulation of the upper and lower teeth. Experiments in guinea-pigs provided evidence that vibration of the teeth leads to transmission of the audio-frequency vibrations by means of soft tissue, through skull foramina, into the skull cavity (brain and CSF) and from there by fluid channels directly into inner ear fluids, exciting the cochlea.

Acoustic Stimulation↗
PubMed1988

Elevation of bone conduction threshold in children with middle ear effusion.

A retrospective study of children having otitis media with effusion revealed fluctuations in bone conduction thresholds as well as in air conduction thresholds. Previous investigations in this area presented both low- and high-tone bone conduction hearing loss which were reversible. We conducted a detailed study including complete otologic, audiologic and tympanometric evaluation of 27 (41 ears) children who had fluctuating bone conduction hearing loss. From these audiologic examinations, 3 types of bone conduction hearing loss could be classified: high-tone, low-tone and flat-type bone conduction hearing loss. We observed the shift of bone conduction thresholds in children after removal of middle-ear fluids by the appropriate medical management.

Audiometry↗
PubMedDate not supplied

Gender effects in auditory brainstem responses to air- and bone-conducted clicks in neonates.

UNLABELLED: Examinations of gender differences in auditory brainstem response (ABR) wave V latencies and thresholds to air- and bone-conducted clicks were undertaken with neonates. Two hundred and two full-term neonates participated (i.e., 103 males and 99 females). Wave V latency measures for air- and bone-conducted click stimuli of 30, 45, and 60 dB nHL and 15 and 30 dB nHL, respectively, and thresholds to air- and bone-conducted clicks were determined. Female newborns displayed statistically significant shorter wave V latencies than male newborns for air-conducted click stimuli (i.e., approximately 0.2-0.3 ms; P=.0016). There were no significant gender differences in wave V latencies to bone-conducted click stimuli (P=.11). With respect to ABR thresholds, no statistically significant differences were observed for either air-conducted clicks (P=.054) or bone-conducted clicks (P=.18). EDUCATIONAL OBJECTIVES: As a result of this activity, the participant will be able to (1) describe gender differences in ABR wave V latencies and thresholds to air- and bone-conducted clicks with neonates and (2) summarize possible explanations for observed gender differences in ABR wave V latencies and thresholds to air- and bone-conducted clicks with neonates.

Auditory Threshold↗
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↗
PubMed2006

Spatial audio through a bone conduction interface.

Headphones are the standard presentation device for radio communication in the military. Although bone conduction devices possess several advantages over headphones for some military applications, they are generally considered inappropriate for inclusion in a multi-channel system. The current study tested the feasibility of a multi-channel bone conduction system by measuring the localizability of spatialized auditory stimuli presented through a pair of bone conduction vibrators. Listeners localized a Gaussian noise stimulus spatialized with individualized head-related transfer functions (HRTFs). The sounds were presented from eight virtual locations on the horizontal plane (0, +/-45, +/-90, +/-135, and 180 degrees ) through either stereo headphones or a stereo bone conduction system. Localization performance was found to be nearly identical for both audio systems, indicating that bone conduction systems can be effectively used for displaying spatial information.

Acoustic Stimulation↗
PubMed1994

Neonatal auditory brainstem response thresholds to air- and bone-conducted clicks: 0 to 96 hours postpartum.

Auditory brainstem response (ABR) thresholds to air- and bone-conducted clicks were investigated in 40 full-term neonates. Subjects were divided into two groups of 20 according to postpartum age: less than 48 hours and between 49 and 96 hours. Mean ABR thresholds to air- and bone-conducted clicks for neonates less than 48 hours postpartum were 14.5 dB nHL (51.5 dB peak SPL) and 1.8 dB nHL (36.8 peak re: 1 microN), respectively, while those for neonates between 49 and 96 hours were 3.8 dB nHL (40.8 dB peak SPL) and 1.5 dB nHL (36.5 dB peak re: 1 microN), respectively. A significant difference was found between the two group mean ABR thresholds to air-conducted stimuli (p < .0001) but not for the bone-conducted stimuli (p < .8959). A statistically significant within-group difference was found between the ABR thresholds to air- and bone-conducted stimuli for only the neonates less than 48 hours of age (p < .0001). When the data was collapsed across groups, simple linear regression analyses revealed a statistically significant relation between postpartum age and ABR threshold to air-conducted stimuli (p < .0001) and a nonsignificant relation between postpartum age and ABR threshold to bone-conducted stimuli (p < .9744). These findings support the notion that some resolution of fluids and residuals in the middle ear occurs during the first 48 hours postpartum and that air-conducted stimuli are attenuated during that period. As such, a physiologic conductive deficit among the younger neonates is suggested.

Acoustic Stimulation↗
PubMed2005

Importance of bone-conducted sound transmission on patient hearing in the MR scanner.

PURPOSE: to evaluate the influence of bone-conduction in the MR environment compared to a standardized acoustic environment. MATERIALS AND METHODS: Acoustic noise is an unwanted side effect of MRI that is commonly tackled with passive hearing protection. In an MR scanner, however, with the patient completely surrounded by the MR sounds and in close contact with the vibrating MR table and gantry, bone-conduction may increase subjective sound levels, restricting the efficacy of passive protection that reduces air-conducted noise only. A total of 10 volunteers were subjected to pure MR tones, covering the frequency range relevant for hearing and at 60 dB, generated through the MR system's gradient coils. Bone-conduction was determined for various passive damping conditions in an MR scanner and was compared to that acquired in an acoustically-calibrated environment. The contribution of mechanical vibrations to bone-conduction was determined. Also, with a microphone in the ear canal, the objective efficacy of the passive protection was measured. RESULTS: We found no difference between the bone-conduction experiments executed inside the imager and in the acoustically-controlled environment. The overall insertion loss of the passive hearing protectors was over 20 dB with strongest effects at 0.4 and 2.5 kHz. CONCLUSION: As bone-conduction is not more pronounced inside the MR scanner than outside, the previous reports on the subjective evaluation of protection devices in MRI hold their validity.

Bone Conduction↗
PubMedDate not supplied

Bone conduction impairment in uncomplicated chronic suppurative otitis media.

PURPOSE: To study the effect of uncomplicated chronic suppurative otitis media on bone conduction thresholds and its relationship to the disease type and duration. PATIENTS AND METHODS: The differences in bone conduction thresholds of diseased and contralateral ears were compared in 218 patients with unilateral uncomplicated chronic suppurative otitis media. Pure tone audiometry was carried out after successful surgery on 93 patients. RESULTS: The study showed bone conduction threshold elevations ranging in frequency from 9.2 to 14.1 dB in the diseased ears. Approximately 39% of the patients had an average difference of more than 10 dB for bone conduction, and 12% had an average difference of 20 dB or more. Significant relationships were found between threshold elevation and the disease type and its duration. Postoperative audiograms showed no significant improvement in the bone conduction thresholds in most of the tested patients. CONCLUSION: This study suggests that chronic otitis media may result in clinically significant bone conduction threshold elevations that should be considered when managing uncomplicated chronic suppurative otitis media.

Adult↗
PubMed1995

[Changes in the auditory threshold for air and bone conduction in relation to middle ear pressure in probands with normal hearing].

Under pressure in the tympanic cavity causes increased impedance of the middle ear. Gellé was the first to describe increased bone conduction levels following alteration of ear canal pressure in healthy ears. Up to now, no investigation which quantitatively describes the elevation of the hearing threshold induced by various levels of under pressure in the middle ear has been published. In a pressure chamber, we induced relative under pressure in the middle ears of 15 adults with normal hearing. We measured hearing thresholds and calculated medium values at four separate levels of under pressure. At an under pressure of 3.3 kPa, air conduction was reduced by a few dB at 500 and 1000 Hz. Alterations of bone conduction were first seen at 6.6 kPa accompanied by increased deterioration of air conduction. Both effects became more obvious at 10 kPa; and at a maximum under pressure of 13.3 kPa, a deterioration of air conduction by more than 25 dB was seen at 250, 500, and 1000 Hz. Bone conduction deteriorated by more than 10 dB at 500 and 1000 Hz. There was no uniformity in the development of bone conduction threshold in the condition of under pressure: Several ears expressed only slight changes, but in some ears we saw an increase of bone conduction at the same rate as air conduction. Minor alterations were observed in frequencies above 1000 Hz. These results may be only partially explained by middle ear effects like the reduction of the ostio-tympanic component of bone conduction caused by increased stiffness of the ossicles. We believe that disturbances of inner ear mechanics play a role in the deterioration of bone conduction levels, too.(ABSTRACT TRUNCATED AT 250 WORDS)

Acoustic Impedance Tests↗
PubMed2006

A finite element model of the human head for auditory bone conduction simulation.

In order to investigate the mechanisms of bone conduction, a finite element model of the human head was developed. The most important steps of the modelling process are described. The model was excited by means of percutaneously applied forces in order to get a deeper insight into the way the parts of the peripheral hearing organ and the surrounding tissue vibrate. The analysis is done based on the division of the bone conduction mechanisms into components. The frequency-dependent patterns of vibration of the components are analyzed. Furthermore, the model allows for the calculation of the contribution of each component to the overall bone-conducted sound. The components interact in a complicated way, which strongly depends on the nature of the excitation and the spatial region to which it is applied.

Bone Conduction↗
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↗
PubMed2006

Better time-intensity trade revealed by bilateral giant magnetostrictive bone conduction.

Sound lateralization tests were performed to compare the magnet coil bone-conduction headphone with the giant magnetostrictive bone-conduction headphone using 18 healthy participants. Although, no significant difference between these bone-conduction headphones was obtained for the interaural time difference and interaural intensity difference, a significant difference was obtained for the time-intensity trade. This revealed that the difference between the headphones is apparent in the integration of the heterogeneous sensations of the time and intensity difference at the cognitive level, but no difference is apparent between the homogeneous sensations of the discrimination of interaural time difference or interaural intensity difference at the sensory level. It was concluded that the difference at the cognitive level indicates the better performance of the giant magnetostrictive headphone.

Acoustic Stimulation↗