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PubMed1986

Reversible and permanent bone conduction threshold shift in cases of chronic suppurative otitis media.

Bone conduction thresholds were measured in sixty-six cases of chronic suppurative otitis media before and after successful oral antimicrobial chemotherapeutic treatment. Comparison of pre- and post-treatment cumulative clinical audiograms of the diseased and the control ears of the same patients disclosed the presence of sensorineural hearing loss with a reversible and a permanent component in the diseased ears. The reversible threshold shift was observed over the higher frequencies, while the permanent threshold shift was equally imposed upon the whole range of the five tested frequencies.

Adolescent↗
PubMed1997

Auditory and tactile bone-conduction thresholds using three different oscillators.

Determination of tactile bone-conduction (BC) thresholds is essential to provide proper diagnosis of individuals with profound hearing loss. In this study, auditory and tactile BC thresholds were compared using three oscillators: the Radioear B-70-A, B-71, and B-72 with mastoid and forehead placement. Subjects included 12 adults with normal hearing (to establish auditory thresholds) and 12 adults with profound sensorineural hearing loss (to establish tactile thresholds). All 24 subjects were tested at octave intervals from 250 through 4000 Hz. As demonstrated in previous studies, tactile thresholds were lower for the low frequencies. Some differences in tactile thresholds were evinced as a function of different oscillators. One fact that emerged from this study is the lower tactile threshold with forehead placement as compared to the mastoid. While ostensibly a disadvantage to forehead BC testing, there are some clinical advantages to be gleaned from this discovery.

Acoustic Stimulation↗
PubMed1995

Auditory brainstem response to bone-conducted clicks in adults and infants with normal hearing and conductive hearing loss.

Knowledge concerning auditory brainstem response (ABR) by bone conduction (BC) is limited, and occasionally controversial. The present study was aimed at further elaboration of this issue. The research population consisted of 107 subjects. Four groups were investigated: group 1, normal-hearing adults aged 20-37 years; group 2, 10 children aged 5.6-8.4 years, with confirmed middle ear effusion (MEE); groups 3 and 4, 22 infants, matched by pairs, aged 5-18 months, 11 with normal otoscopy and 11 with suspected MEE. Comparison between ABR by AC and BC for all four groups is discussed. We observed that the AC-ABR threshold of group 2 was statistically significantly elevated compared to group 1. The same tendency was observed for group 4 compared to group 3. In AC ABR, the mean latency of wave V was significantly prolonged, compared to that of BC ABR in children with confirmed MEE, and infants with suspected MEE. We strongly suggest that by combining AC and BC ABR, more information concerning cochlear reserve status can be obtained in infants and young children who are difficult to test, or wherever a behavioral audiogram cannot be achieved.

Adult↗
PubMed2001

Bone conduction impairment in chronic ear disease.

The preoperative and postoperative bone conduction (BC) thresholds were prospectively investigated in 24 patients with chronic ear disease in the form of cholesteatoma, chronic suppurative otitis media, or adhesive otitis media. All underwent tympanoplasty with mastoidectomy. Ossicular reconstruction was performed in 14, and the remaining 10 were still awaiting second-stage ossicular reconstruction at the time of this investigation. In each group, the postoperative results were compared with the preoperative results by the paired-samples t-test. In the ossicular reconstruction group, the results revealed a significant improvement in the postoperative BC thresholds, as compared with the preoperative BC thresholds, at 250, 1,000, and 2,000 Hz, with the largest mean improvement observed at 2,000 Hz. No significant improvement was observed at any frequency for the group without ossicular reconstruction. Postoperative improvement of at least 10 dB at 2 or more frequencies was observed in 71% of the ossicular reconstruction group, as compared with 0% of the group that did not undergo ossicular reconstruction. The results support the theory that the elevated BC thresholds of patients with chronic ear disease result from the elimination, due to disease, of the middle ear contribution (from the inertial ossicular component and ossicular resonance) to the BC response. The results also suggest that the middle ear contribution to the BC response is restored with ossicular reconstruction.

Adult↗
PubMed1980

[The influence of tympanoplasty on bone conduction (author's transl)].

Seldom tympanoplasty damages the inner ear in a substantial amount: From 1814 operations upon chronic inflamed ears 4 patients (0.22%) became deaf, among the other patients bone conduction (b.c.) in the mean increased at 1000 cps for + 0.8 dB and decreased at 4000 cps for - 2.2 dB. In 9.8% b.c. showed an improvement for 10 dB or more at 1000 and 4000 cps, 9.7% showed an corresponding deterioration. For patients it was confirmed on a statistical base, that the influence on bone conduction demonstrated by animal experiments (Tonndorf), was mainly the result of changing the compliance of oval window and of increasing ossicular inertia. By relieving a mobile stapes of an incus which was fixed in the attic, there results an improvement of mobility of the stapedial footplate with increasing b.c. at 1000 and 4000 cps. By interposition of an incus between tympanic membrane and stapes and by myringoplasty with fascia there results an increasing ossicular inertia with increasing b.c. at 1000 cps and decreasing b.c. at 4000 cps. Noise trauma, mechanical trauma and infection are only of slight importance, only in some single cases they will damage the inner ear in a substantial amount.

Bone Conduction↗
PubMed1997

Normative auditory brainstem response data for bone conduction in the dog.

Auditory brainstem response (ABR) is a valuable tool for the diagnosis of hearing disorders in dogs, but is hampered by the lack of published normative data. The aim of the present study was to obtain normative data for bone conduction, without masking, under clearly defined conditions. Subjects comprised 20 Dalmatians and 20 Jack Russell terriers. Two methods were investigated: holding the bone vibrator against the head by hand or by applying a 500 g weight. The results revealed no difference in hearing threshold between the two breeds or for the two methods of applying the bone vibrator to the head. The mean hearing threshold was close to 0 decibels re normal hearing level (dB nHL), which is the biological norm for humans. Hence, bone conduction thresholds can be used for confirmation of conductive hearing impairment in the dog, in the same way as in humans.

Animals↗
PubMed1976

Input-voltage method of bone-conduction calibration.

Several methods have been proposed for calibrating the bone-conduction section of an audiometer. Because of its low cost and ease of implementation, the input-voltage method is attractive. Only one previous investigation has assessed this calibration method and found it to be lacking. With the availability of updated "required voltages," a reexamination of this calibration method was warranted. Audiometric corrections were determined for 21 combinations of audiometers and bone vibrators at five test frequencies with an artificial-mastoid system. These corrections were compared with those determined with the input-voltage method. The latter yielded corrections that agreed directly with or deviated no more than 5 dB from artificial-mastoid corrections 93.4% of the time and deviated by 10 dB only 6.6% of the time. The use of the input-voltage method for clinical calibration is advocated in the absence of an artificial mastoid.

Audiometry↗
PubMed1990

An electrical network model of inertially induced bone-conducted sound.

A model for the description of inertially induced bone-conducted sound has been developed and a discussion of the appropriate techniques for its representation as an electrical network is described. Predictions are made for the sound pressure produced in the meatus in the cases of normal ears and pathological ears resulting from vibration applied to the skull. Evidence from this modelling suggests that the technique may provide improved discriminability over conventional immitance measurements for some types of pathology.

Acoustics↗
PubMed1982

A standard determination of paired air- and bone-conduction thresholds under different masking noise conditions.

Air-(ac) and bone-conduction (bc) thresholds were determined for 96 subjects in the age range 16-30 years. The bc tests were carried out using a B-71 vibrator applied to left and right mastoid under three conditions at the contralateral ear: unoccluded, masked at 25 dB and at 40 dB sensation level; ac audiometry and masking noise used a TDH-39 earphone. By a systematic process of otological classification of the subjects, the bc threshold for 'normal hearing' could be estimated with an uncertainty of less than 1 dB and interpolated for masking noise levels from zero to 40 dB sensation level. Results are expressed as alternating force levels in an artificial mastoid of current commercial design. Variance of the air-bone difference for individual ears is found to be less than the sum of ac and bc threshold variances calculated separately, implying strong air-bone correlation. Comparison is made with other recent studies using B-71 and KH-70-type vibrators, and average results are presented in the context of a proposed international standard for the normal threshold of hearing by bc.

Adolescent↗
PubMed2002

Factors contributing to bone conduction: the middle ear.

Measurement of the motion of the malleus umbo and stapes footplate during bone conduction (BC) stimulation was conducted in vitro in 26 temporal bones using a laser Doppler vibrometer over the frequency range 0.1 to 10 kHz. For lower frequencies, both ossicular sites followed the motion of the temporal bone. The differential motion between the malleus and the surrounding bone was greater than the differential motion of the stapes footplate; both resonated near 1.5 kHz. Different lesions were shown to affect the response: (1) a mass attached to the umbo lowered the resonance frequency of the ossicular vibration; (2) fixation of either the malleus or stapes increased the stiffness and shifted the resonance frequency upward; and (3) dislocation of the incudo-stapedial joint did not significantly affect the ossicular vibration. The sound radiated from the tympanic membrane was approximately 85 dB SPL at an umbo differential velocity of 1 mm/s for low frequencies in an open ear canal and about 10 dB higher for an occluded one; at higher frequencies (above 2 kHz) resonances of the canal determine the response. It was also found that the motion between the footplate and promontory was within 5 dB when the specimen was stimulated orthogonal to the vibration direction of the ossicles than in line with the same. Measurement of the differential motion of the umbo in one live human skull gave similar response as the average result from the temporal bone specimens.

Bone Conduction↗
PubMed1979

Bone conduction changes following successful tympanoplasty type I.

Pre and one year postoperative bone conduction (b.c.) thresholds were compared for 50 ears of 48 patients, ranging in age from 14 to 42 years, in whom successful tympanic grafts resulted in at least an average improvement of 10 db for 500 to 4000 Hz. While pre and postoperative data are included for all ears and test frequencies, significant BC improvement is seen only at those frequencies, in each case, where the pre-op BC thresholds were worse than 10 db. Normal pre-op BC thresholds cannot show substantial improvement because of audiometric limitations. The amount of BC shift at each frequency for those with pre-op BC thresholds that were subnormal averaged 6 db at 500 Hz, 13.3 db at 1000 Hz, 13.8 db at 2000 Hz and 9 db at 4000 Hz, all highly significant statistically. There were no significant postoperative BC shifts related either to duration of the disease process, length of postoperative period before final test (all were more than one year) or whether the surgical procedure was tympanoplasty type I or myringoplasty.

Adolescent↗
PubMed2006

Craniocentric body-sway responses to 500 Hz bone-conducted tones in man.

Whole-body responses evoked by bone-conducted sound, a stimulus known to activate vestibular afferents, were recorded in standing subjects deprived of vision. With the head facing forward, unilateral mastoid vibration (500 Hz, 2 s, 136 dB force level) produced an oblique body sway with a consistent lateral component away from the stimulated ear and an average forward component. The side of stimulation had a powerful influence on the direction but not the magnitude of sway. Individuals' mean response directions were significantly clustered between subjects, as well as within subjects for 12 of 16 subjects when tested on five occasions. Single trial analysis did not reveal any habituation of the response. To investigate whether muscle spindle activation might be responsible for the response, vibration was applied directly over posterior and anterior neck muscles and tendons. This generally produced responses that were smaller and with different direction characteristics than with mastoid vibration. In contrast, stimulation over the temporal fossa produced responses similar in magnitude and direction to mastoid stimulation. When the head was turned in yaw to face in different directions the sway response changed direction by the same amount but with no change in magnitude, suggesting response organization in a craniocentric reference frame. Whole-body sway evoked by 500 Hz vibration delivered over sites close to the ear is thus likely to represent a vestibular-evoked balance response. When compared with sway responses evoked by 500 Hz vibration of the left temporal fossa, responses to 1 mA left cathodal galvanic vestibular stimulation were of similar magnitude, yet significantly different in direction, suggesting differences in the end organ afferents activated by these two stimuli. This may enable investigation of previously inaccessible aspects of vestibular function in intact freely behaving human subjects.

Acoustic Stimulation↗
PubMed1989

Clinical experience with the Xomed Audiant osteointegrated bone conducting hearing device: a preliminary report of seven cases.

An osteointegrated bone conducting hearing device has recently become available in North America. As with any new medical treatment, initial enthusiasm is soon tempered by its inherent limitations. Critical and objective analysis of results and candid reporting of clinical experiences will lead to the establishment of realistic indications for any new treatment. We present the current indications for insertion of the Xomed Audiant Bone Conductor, our early clinical experience and our thoughts on its future role in the management of patients with conductive hearing loss.

Adult↗
PubMed2003

Estimating bone conduction transfer functions using otoacoustic emissions.

A technique for estimating the nonparametric bone conduction transfer function using distortion product otoacoustic emissions (DPOAEs) is presented. Individual transfer functions were obtained using DPOAEs recorded from a single ear of five normal-hearing adults. Repeatability of the technique was investigated by performing measurements on at least three dates. Functions were reasonably repeatable, and were unique to each individual as expected from subjective measurements. Input force and DPOAE measurements were made for each individual, and a model of the auditory periphery representative of an average person was employed. The technique is objective and requires only passive cooperation, but robust DPOAEs are needed and the measurement time can be onerous for a wide frequency band or fine frequency resolution. With appropriate adjustments to the model of the auditory periphery, the method could be applied with animal models.

Acoustics↗
PubMed1980

Preoperative bone-conducted electrocochleography in otosclerosis.

Prior to surgery, pure-tone audiometry and bone-conducted (BC) electrocochleography (ECOG) were performed on 17 patients with preoperatively diagnosed otosclerosis. Short tone bursts, approximately 5 ms in duration and presented by means of a bone conductor on the exposed surface of the mastoid, were used as stimuli in BC ECOG. The thresholds thus obtained were compared by regression analysis with conventional psychoacoustic thresholds. Thresholds recorded at BC ECOG showed a close correlation to preoperative pure-tone BC thresholds, and there was no difference in predictability of postoperative hearing thresholds between preoperative BC ECOG and conventional preoperative pure-tone BC thresholds. The results lend support to the conclusion that BC ECOG, offering a monaural, objective estimation of cochlear function, is a valuable complement to conventional audiometry in the preoperative evaluation of hearing in otosclerosis.

Audiometry↗
PubMed1979

The effect of bone conduction on the intensity independence of dichotic chords.

The relative salience of the pitch components of a two-tone dichotic chord is invariant with respect to the relative intensity of the two tones over a wide range of interaural intensity differences [R. Efron and E. W. Yund, J. Acoust, Soc. Am. 889--898 (1976)]. According to a recently developed model, the range of intensity independence is limited by the bone-conducted energy from the more intense tone [E. W. Yund and R. Efron, J. Acoust. Soc. Am. 62, 607--617 (1977)]. The model predicts that a decrease in bone conduction such as the one achieved by using insertion earphones, must increase the range of intensity independence. This prediction is confirmed.

Bone Conduction↗
PubMed1993

Observations on temporal aspects of bone-conduction clicks: real head measurements.

To further elucidate nuances of bone-conduction (BC) stimulation, particularly as they may pertain to BC-elicited auditory brainstem responses (ABRs), real head measurements were made of vibratory responses to BC clicks. A miniature accelerometer was held firmly against the skull near a bone vibrator applied to the mastoid, to the opposite mastoid, and to the forehead. Measurements also were made with the vibrator applied to the forehead and the accelerometer placed on a mastoid. The measured vibrations were compared among conditions within and across subjects. The results demonstrate that vibration picked up in the immediate vicinity of the vibrator, roughly mimics the temporal and spectral characteristics of the click observed on an artificial mastoid. However, probing at sites remote to the bone vibrator suggested the introduction of a propagation-like delay as well as low-pass filtering. These findings support observations of previous researchers who demonstrated phase differences between vibrations recorded at different points on the skull, further demonstrating the complexities of skull vibration. Latency differences of ABR responses obtained with forehead versus mastoid placements, for example, cannot be attributed merely to the difference in efficiency between sites of stimulation demonstrated audiometrically. While the real head observations do not permit determination of the actual vibratory lag at the cochlea, they do permit the deduction that a comparable onset delay occurs in BC as in air-conduction stimulation via supra-aural earphones.

Acoustic Stimulation↗
PubMed1990

Use of the bone conduction ABR Wave I response in determination of cochlear reserve.

Interest in bone-conducted stimulus auditory brainstem response (BC-ABR) testing has centered around evaluation of cochlear integrity in neonates and in patients who are difficult to evaluate audiometrically. The present study was designed to evaluate the Wave I component of the BC-ABR and to determine the utility of this response in assessment of cochlear reserve. The source of Wave I has been shown to be the distal eighth nerve. It was postulated that the presence or absence of this component would provide ear specific information useful for determination of cochlear integrity. In order to test this hypothesis, patients with a documented unilateral hearing loss were studied. Stimulus presentation was via the Radioear B-70 bone vibrator used in conventional audiometric assessment. Evoked potential responses were recorded at four presentation levels. Subjects had either normal hearing bilaterally or normal hearing in one ear and a mild-to-profound sensorineural hearing loss in the opposite ear. Our data indicate that the Wave I response, when measured in this fashion, is ear specific. Ear specificity was shown to be aided by good waveform morphology, as typically observed in younger subjects, and by a relatively large discrepancy in hearing thresholds between the normal and hearing-impaired ears. This technique may be of value in determination of cochlear reserve in patients with problematic masking dilemmas.

Adult↗