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PubMed1986

The effect of coupling force on bone conduction audiometry.

The present research is devoted to the study of the effect of coupling force on bone conduction threshold determination. The following characteristics of this investigation are listed: A systematic range of coupling forces from 250 to 750 grams (in 100-gram intervals) is used by means of some adopted mechanical devices; A Brüel & Kjaer mechanical impedance head type 8000 (with a mini-shaker) is employed for testing; Test-retest variabilities of bone conduction thresholds are analysed under different coupling forces; Variation of hearing levels under the effect of coupling force is studied.

Adult↗
PubMed1993

Bone conduction errors at high frequencies: implications for clinical and medico-legal practice.

The magnitude and origin of audiometric air-bone gaps in the range 3 kHz to 8 kHz was investigated in 20 normal subjects. The average gap ranged from a minimum of about 3 dB at 3 kHz to a maximum of about 19 dB at 6 kHz. Approximately 5 dB of the gap at high frequencies is caused by excess air-radiated sound from the bone vibrator. A larger error appears to result from discrepancies between the air and bone conduction standards to which audiometers are calibrated. These errors may influence diagnosis and we recommend that bone conduction tests at frequencies greater than 4 kHz are avoided. These findings have implications for medico-legal work where small air-bone gaps have diagnostic significance.

Audiometry, Pure-Tone↗
PubMed1990

Clinical application of an implantable bone conduction hearing device.

For some patients, the transcutaneous bone-conduction implant offers a viable alternative to conventional amplification. However, this option should be employed only after considering the relative advantages and disadvantages of conventional medical management and, when feasible, the fitting of air-conduction amplification. The cases presented here illustrate some important factors to consider in the selection and fitting of bone-implant candidates.

Adult↗
PubMed1979

Bone conduction mechanisms: Mössbauer measurements on the role of ossicular inertia.

The Mössbauer technique was used to measure displacements of the stapes footplate and adjacent temporal bone during bone conduction stimulation at frequencies from 250 to 400 Hz in anaesthetized guinea pigs. The stapes was found not to be driven at amplitudes or phases that differed significantly from those of the temporal bone. Measurement of stapes displacements during air conduction stimulation, and of temporal bone displacements during bone conduction stimulation producing matching cochlear microphonic amplitude, enabled calculation of limiting values of amplitude and phase difference necessary to produce the required relative displacement. The obtained values (less than 1 dB for amplitude and 1--4 degrees for phase) were beyond the resolution of the measurement system employed for reasonable nuclear counting times. The results provide quantitative estimates of the magnitude of inertial effects, but do not establish whether ossicular inertia is an important factor in bone conduction stimulation.

Acoustic Stimulation↗
PubMed1998

[Acute otitis media with bone conduction hearing loss associated with acute mastoiditis].

Acute otitis media, generally complicated by conductive hearing loss, sometimes shows raised bone conduction thresholds. Five patients with acute otitis media with mixed hearing loss and much otorrhea were reported. The chief complaints were otalgia in 3 patients, hearing loss in 4, ear fullness in 1 and tinnitus in 1. Four patients had moderate hearing loss. At the first examination, the tympanic membrane showed swelling and injection, while 2 showed bullous myringitis, with swelling of the tympanic mucosa and a yellowish serous discharge following myringotomy. Positive mastoidal CT of all patients without acute inflammatory symptoms in the external ear suggest the complication of acute mastoiditis. After treatment with antibiotics and myingotomy for all patients, steroidal administration for 4, and tympanostomy tube insertion for 3, the hearing levels of 4 patients improved. Sensorineural hearing loss (51.3 dB) remains in 1 patient with sever hearing loss at the first examination. It is important to determine the hearing level for patients with acute otitis media, especially if it is complicated by hearing difficulties.

Acute Disease↗
PubMed2002

[Late deterioration in bone conduction after stapes surgery: a retrospective analysis].

In spite of the well-consolidated technique that otosclerosis surgery has built up, there are several aspects that have yet to be satisfactorily explained. One of these is the greater long-term "vulnerability" that appears to characterize an ear that has been operated on compared to a healthy one. In searching for a feasible explanation of this phenomenon and its therapeutic implications, a retrospective analysis of 26 cases was carried out on patients who had been operated between 1966 and 1995 and had come to our attention between 1989 and 1999 due to a rapid, late deterioration in bone conduction. Short-term treatment was pharmacological and surgical in 19 cases and exclusively pharmacological in 7 cases. The analysis of the results of therapy was based on an evaluation criterion of PTA (250-4000 Hz) > 5 dB, calculated on the basis of the bone conduction threshold values. Possible prognostic factors were searched for by means of a multivariate analysis that took as its dependent variable the bone conduction hearing threshold following therapy and as independent variables the age, gender, monolaterality of the otosclerosis ascertained, a positive medical history for analogous phenomena and for previous surgical revision, concomitant vertigo, the time that had elapsed between initial treatment (operation) and deterioration, the technique adopted during the first operation, the extent of the rapid deterioration, the audiometric characteristics at the outset of treatment for the acute episode, the time that had elapsed between deterioration and treatment, the type of treatment, possible reopening of the oval window, and intraoperative findings of a perilymphatic fistula. In the 7 cases managed with pharmacological therapy alone, improvement was seen in 3 cases while the condition remained unvaried in 4 cases; surgical revision (which in 5 cases enabled the presence of a fistula to be ascertained) associated with pharmacological therapy brought improvement in 4 cases, worsening in 4 cases, and no variation of the condition in 11 cases. The only prognostic factor detected, of an unfavourable nature, was the presence of anacusis upon examination. The results obtained do not enable unambiguous conclusions to be drawn: it may in any case be inferred that, at least in certain particular cases, above all when a false cochlear deterioration or the presence of a fistula is suspected, an "aggressive" therapeutic approach may be justified.

Adult↗
PubMed1994

Effect of high-pass filtering on the neonatal auditory brainstem response to air- and bone-conducted clicks.

The effect of standard high-pass analog filtering on the neonatal auditory brainstem response (ABR) to air- and bone-conducted clicks at low intensity screening levels was investigated. Simultaneous three channel recorded ABRs were obtained from 20 neonates with filter settings of 30-3000, 100-3000, and 150-3000 Hz at intensity levels of 20, 30, and 40 dB nHL. Statistically significant reductions in wave V amplitude and decreases in wave V latency were observed for both transducers across all three low level stimulus intensities with the progressive increase in the high-pass filter cutoff (p < .05). These data support the advocacy of less restrictive high-pass filtering (e.g., 30 Hz) for neonatal and infant ABR screening to air- and bone-conducted clicks.

Adult↗
PubMed1991

Experience with a subcutaneous implantable bone conduction hearing aid (Xomed Audiant) in a district general hospital.

Patients with a conductive hearing loss may find conventional hearing aids unsatisfactory for a variety of reasons. Efforts to overcome some of these difficulties have led to the development of the osteointegrated hearing aid. Implantable bone conduction hearing aids are an important advance in the treatment of well selected patients. Only 18 patients, who have been implanted with the Xomed Audiant bone conduction hearing aid, have so far been reported on in the UK. This report concerns a further six patients who have been implanted in one centre. Five of these patients continue to use their Audiant hearing aid 14 to 24 months after being fitted. They regard it to have significant advantages over their previous hearing aids. Four of the five patients use an ear level processor. Two of the patients who had previously used conventional bone conduction hearing aids now use the ear level processor.

Adolescent↗
PubMed1976

Bone conduction thresholds for normal listeners in force and acceleration units.

In a previous article we reported on the standardization of normal hearing for bone conduction. All of our findings were reported in force units. Because many international users of this information express such findings in units of acceleration, we have, at the Editor's request, converted our force units into acceleration units to increase the scope of our results and to enhance their comparison with other investigations. This note presents data which may be useful to organization concerned with the development of standards for normal hearing by bone conduction.

Acceleration↗
PubMed1999

The BAHA HC200/300 in comparison with conventional bone conduction hearing aids.

A retrospective study was performed on 89 patients from a consecutive series who received a BAHA HC200/300 after having previously used conventional bone conduction hearing aids. The patients' performance with the BAHA HC 200/300 was compared to their performance with conventional bone conduction hearing aids. The patients were divided into two groups, depending on the time of implantation (before or after May 1992). The patients in group 1 (long-term users) were asked to fill in a questionnaire, the same one as they had filled in at the initial BAHA fitting more than 5 years previously. The answers were compared to their original opinions and difference scores were calculated. The long-term clinical results from group 1 are also presented. Although they are encouraging, the patients' opinion about the BAHA deteriorated somewhat over time. The audiometric results of group 2 were highly comparable with those of group 1. This confirms the positive results with the BAHA found in previous studies.

Acoustic Stimulation↗
PubMed2001

The latency of auditory nerve brainstem evoked responses to air- and bone-conducted stimuli.

The auditory nerve brainstem evoked responses (ABRs) to bone conduction (BC) stimuli are longer in latency than those to air conduction (AC). In order to study the mechanism of this difference, ABR wave I was recorded in experimental animals in response to low intensity (0-20 dB above their threshold) logon stimuli delivered by BC and by using the same bone vibrator to generate the air-conducted stimulus. The BC stimuli were delivered to skull bone, and directly to the contents of the cranial cavity (brain and cerebrospinal fluid) through a craniotomy. ABR wave I in response to BC stimuli delivered to skull bone was significantly longer in latency than that to BC delivered on the brain, while there was no latency difference between AC stimuli and BC to the brain. Furthermore, the vibration (measured with an accelerometer) recorded on the brain during BC stimulation of skull bone was always delayed compared to that measured on the skull. Thus there is a delay in the transfer of vibratory energy from the skull bone to the underlying contents of the cranial cavity. From there, the delayed vibrations of the contents of the cranial cavity are transmitted to the inner ear. This is probably the mechanism of the longer latency BC response compared to the AC response.

Acoustic Stimulation↗
PubMedDate not supplied

[Bone conduction receiver for the measurement of the auditory thresholds over a broad frequency range].

A piesoelectric bony telephone for determining audible thresholds while sound is conducted through the bone over expanded frequency range of 0.25 kHz up to 20.0 kHz is described. Fundamental limitations of electromagnetic bony telephones preventing them from metering audible thresholds at the frequencies greater than 6 kHz have been revealed. Analysis of the piesoelectric transducer equivalent circuit has demonstrated on principle the possibility to measure audible thresholds with such a device over the expanded frequency range to 20 kHz. A model of piesoelectric bony telephone conforming the IEC recommendations is described and some experimental results obtained for the frequency range of 0.25 kHz to 20.0 kHz are presented.

Audiometry↗
PubMedDate not supplied

Skull distortion of bone conducted signals.

A previously essentially unknown type of distortion of bone conduction (BC) signal has been studied on the skulls of four human cadavers. The method was based on a miniature accelerometer, rigidly attached to the cranial bone, converting the skull vibration close to the cochlea into an electrical signal which was analysed with regard to harmonic distortion. The BC signals, pure tones, were presented by means of a high-quality vibrator. The distortion was found to be limited to the lower audiometric frequencies, with a maximum around 500 Hz, and of such a degree as to be able to significantly influence the results of BC audiometry. The distortion is probably caused by nonlinear mechanical properties of the human skull.

Audiometry↗
PubMed1991

[A hearing aid anchored in the cranial bone for amplification of bone conduction].

The purpose of this study was to compare hearing and understanding with a bone conduction hearing aid of a new type and with conventional models. The new instrument, BAHA (bone anchored hearing aid) is connected with the skull percutaneously rather than transcutaneously as with the conventional instruments. In the ENT department of Nijmegen University Hospital the understanding of speech with both types of hearing aid was evaluated thoroughly. The patients had a middle-ear loss with in addition an inner-ear loss of 60 dBHL at most. A conventional air conduction hearing aid (behind or inside the ear) was unsuitable for them because of, for instance, chronic runny ears or anomalies of the auditory meatus. A conventional bone conduction hearing aid containing a transducer pressing on the skin was rejected because of poor understanding or serious side effects such as headache and pressure pains. At the first session a titanium screw was implanted in the skull behind the ear. The percutaneous superstructure was put into place a few months later at a second session. In none of the patients were there peroperative problems or postoperative infections of any importance. Understanding of speech in silence and in noise was evaluated with the BAHA and with the conventional aid. Differences in understanding of speech were regarded as significant if they amounted to more than twice the known intra-individual standard deviation. As to understanding of speech in silence, 7 of the 15 patients were found to understand significantly better with the BAHA than with a conventional aid. In the other patients no difference was found.(ABSTRACT TRUNCATED AT 250 WORDS)

Bone Conduction↗
PubMed1989

[Brain stem evoked response audiometry study with a bone conduction receiver in atresia of the auditory canal and microtia].

Conductive hearing loss may be determined from the latency delay of the brainstem auditory evoked response Jewett V, if other reasons that may prolong latency are ruled out. Therefore it is important to determine the bone conduction threshold when examining infants. Two bone vibrators have been chosen, which, with the help of "inverse filtering", provide the possibility of a good sound conduction of the click stimulus and thus a measurement near the hearing threshold. When applying bone vibrators to infants it must be borne in mind, that the sound transfer is reduced because the cranial sutures are not yet closed. The measurement of bone conduction is suitable for securing the result of high-grade combined hearing defects. In two cases of atresia of the external auditory canal and microtia brainstem evoked response audiometry is presented with evaluation of both air and bone conduction.

Adult↗
PubMed1981

Pre-operative bone conduction curves in stapedectomy.

Significant post-stapedectomy cochlear deficit is associated with the following factors in an uncomplicated operation: (1) The age of the patient. (2) A pre-operative bone conduction loss, averaged over 0.25, 0.5, 1.0 and 2.0 KHz, of 20 db or more. (3) A left-to-right sloping bone conduction curve (descending audiometric curve), especially where there is a similar curve in the other ear.

Adult↗
PubMed2001

Bone-conducted sound lateralization of interaural time difference and interaural intensity difference in children and a young adult with bilateral microtia and atresia of the ears.

Bone-conducted sound lateralization tests to determine interaural time difference (ITD) and interaural intensity difference (IID) were conducted by means of a self-recording apparatus in 20 children and a young adult with bilateral microtia and atresia of the ear. This apparatus changes ITD automatically from 0 to 2,000 micros at 50 micros/s and IID from 1 to 40 dB at 1 dB's. When ITD exceeds approximately 200 micros/s and IID exceeds 5 dB in normal subjects the sounds are recognized separately. The test stimulus was a continuous narrow-band noise at 500 Hz and 30 dB SL applied to the right and left mastoids through bone vibrators. In the patients with bilateral atresia of the ears, ITD results revealed approximately normal thresholds of discrimination in half the patients and IID results revealed threshold elevation in only 10%. It is noted that bone-conducted sound lateralization abilities of ITD or IID are maintained in many of these patients.

Adolescent↗
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↗