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At least 127 records · Page 7Linked to original sources
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↗
PubMed1991

Implantable bone-conduction hearing device: practical considerations.

An implantable bone conduction hearing device can be of significant benefit to carefully selected patients with noncorrectable conductive hearing losses. However, for some patients the device has significant limitations. This paper presents several practical issues that need to be considered before a decision is made regarding implant surgery. It is recommended that, whenever possible, air conduction hearing aids remain the first option considered when a patient's conductive hearing loss cannot be resolved through traditional medical management.

Adult↗
PubMedDate not supplied

Spectral characteristics of air and bone conduction transducers used to record the auditory brain stem response.

This study sought to determine differences in the acoustic spectra of five different transducers commonly used for stimulus presentation to record the auditory brain stem response (ABR). The outputs of three commercially available bone conduction vibrators (Radioear B-70A, B-71 and B-72), a TDH-49 earphone, and an insert receiver were measured by applying a 0.1 msec rectangular electrical pulse to each transducer. The resultant output for each transducer was converted to one-third octave band data and plotted against reference threshold levels. Results demonstrated relatively flat acoustic spectra and high output levels for the two air conduction receivers. In contrast, each of the bone oscillators had its greatest concentration of energy in the 2000 Hz region with the spectrum characterized by a precipitous decrease in output at frequencies above and below this resonance peak. Maximum output never exceeded 35 dB HL for any of the three bone conduction devices. Of the three oscillators, however, the B-70A appeared to provide the highest output before reaching saturation. Results are discussed relative to the limitations for recording the auditory brain stem response to bone conducted transient signals.

Audiometry, Evoked Response↗
PubMed1983

Elevated bone conduction thresholds associated with middle ear fluid in adults.

Longitudinal observations of adult patients with documented cases of otitis media revealed fluctuations in bone conduction thresholds as well as air conduction thresholds. Previous investigations in this area presented conflicting information regarding temporary and permanent effects of serous otitis media on sensori-neural function. We conducted a detailed study, including complete otologic, audiologic, and tympanometric evaluation, of 30 adult patients exhibiting serous otitis media. Myringotomies were performed on all patients after appropriate medical management failed to clear the middle ear fluid and subsequent hearing loss. Pre- and postmyringotomy audiograms support our conclusion that middle ear fluid can produce artifactual shifts in bone conduction thresholds. Although the data presented was collected from a cohort of adults, the clinical implications are applicable to the pediatric population. We have observed a similar shift in bone conduction thresholds in children exhibiting serous otitis media, and we have observed improvement in the thresholds with removal of the fluid either by appropriate medical management or by myringotomy with fluid aspiration.

Adult↗
PubMed1981

[Brain stem evoked response audiometry via air- and bone-conducted stimulation (author's transl)].

Brain stem potentials can be released by bone-conducted stimulation. The spectral composition of the skull vibration being generated by ton-bursts (1, 2, 4 and 8 kc) were recorded from several positions of the head. Combined acoustic stimulation via air- and bone-conduction (BERA) enables, on principle, a differentiated statement of sound conduction and inner ear components of hypacusis in infancy, analogous to conventional audiometry.

Acoustic Stimulation↗
PubMed1992

Frequency specificity of the auditory brain stem response to bone-conducted tones in infants and adults.

Auditory brain stem responses were obtained from normal-hearing infants and adults in response to bone-conducted 500 and 2000 Hz tones presented in quiet and high-pass noise masking. The tones were presented at 70 (500 and 2000 Hz) and 46 (2000 Hz) dB peak to peak equivalent (re: 1 dyne RMS). The high-pass noise-masked waveforms were subtracted in succession to obtain derived responses, providing estimates of the cochlear regions contributing to the nonmasked responses. Findings indicate that the auditory brain stem response to bone-conducted 500 Hz tones is frequency specific for both infants and adults. For 2000 Hz tones, the results show maximum amplitudes for cochlear regions representing the nominal frequency of the tone for adults. For infants, maximum response amplitudes for the derived responses to 2000 Hz, 70 dB tones were obtained within 1/2 octave of the nominal frequency (1410-2000 Hz). Wave V latencies of the derived responses are similar for both groups for 2000 Hz tones, but shorter for infants to 500 Hz tones, supporting the hypothesis that low-frequency bone-conducted stimuli are effectively more intense in infants than adults.

Acoustics↗
PubMed2003

Basilar membrane and osseous spiral lamina motion in human cadavers with air and bone conduction stimuli.

It is generally accepted that bone conduction (BC) stimuli yield a traveling wave on the basilar membrane (BM) and hence stimulate the cochlea by the same mechanisms as normal air conduction (AC). The basis for this is the ability to cancel or mask a BC tone with an AC tone and the ability to generate two tone distortion products with a BC tone and an AC tone. The hypothesis is proposed that BC stimulates the BM not only through the hydrodynamics of the scala vestibuli and scala tympani, but also through osseous spiral lamina (OSL) vibrations. To test this hypothesis the BM and OSL response with AC as well as BC stimulation was measured with a laser Doppler vibrometer. Human temporal bones mounted on a shaker were used to record the velocities of the bone per se, the BM and the OSL. The measurements were then converted to relative BM and OSL velocities. The results from the basal turn of the cochlea show similar behavior with AC and BC stimulation. The motion of the OSL at the edge where it connects to the BM is in phase and is typically 6 dB lower than the BM motion. With BC stimulation, there is less phase accumulation in the OSL after the cochlea is drained; the OSL moves due to inertial forces and resonates at approximately 7 kHz. Inertial vibration of the OSL may partially contribute to the total response of BC sound, especially at the high frequencies, although current models of the cochlea assume a rigid OSL. The measurements reported here can be used to include a flexible OSL in cochlear models.

Acoustic Stimulation↗
PubMedDate not supplied

Effects of reflex middle-ear muscle contractions on cochlear responses to bone-conducted sound.

The effects of contralaterally elicited middle-ear muscle (MEM) reflexes on cochlear microphonic responses to air- and bone-conducted tones were examined in decerobrate cats. Stapedius effects on bone condn air conduction were almost identical in configuration and amplitude to those on air conduction at all frequencies. However, tensor tympani effects were more complex, the configuration of the bone-conduction effects varying with the location of the transducer on the skull and with frequency. The relative contributions of the two muscles to the effects of joint contractions varied markedly between animals. It is suggested that non-reflex MEM contractions associated with activity of the facial musculature might provide protection against masking of environmental sounds by the low-frequency bone-conducted sound generated by such activity.

Air↗
PubMed1988

High-frequency audiometry: comparison of electric bone-conduction and air-conduction thresholds.

Thresholds have been measured with two commercially available high-frequency (HF) audiometers providing respectively air-conduction (AC) and electric bone-conduction (EBC) stimulation. Normative values for the latter have been obtained, and the reduction of HF sensitivity with both stimulus modes documented in two groups aged 50-59 and 70-79 years. EBC reproducibility is of the same order of magnitude as the AC signal through 14 kHz, while the dynamic range is limited to 50 dB. Lateralization of the EBC signal occurs up to at least 17 kHz. The logarithmic conversion factor of Tonndorf and Kurman [Ann. Otol. Rhinol. Lar. 93: 576-582, 1984] does not result in equivalent AC and EBC thresholds at all frequencies, but does provide similar loudness sensation increases. The 40 log (i) re 1 mA conversion factor must be adjusted with a frequency-dependent additive correction.

Adult↗
PubMedDate not supplied

Bone-conducted stimulation in electrocochleography.

The mechanical vibration patterns close to the cochlea in intact skulls of human cadavers have been studied by means of a miniature accelerometer. A Radioear B70A vibrator and a Brüel & Kjaer Mini Shaker have been used, fed with filtered clicks and with short tone bursts. The tone bursts were found to be superior to the clicks with regard to the vibration spectrum. At 500 Hz a considerable distortion was observed in the accelerometer signal, also when using tone bursts. This distortion was presumably due to resonant vibrations in the skull itself, and may be a source of error not only when using stimuli of short duration as in bone-conduction ECoG but also in conventional bone-conduction audiometry. When the vibrations were applied to the exposed bone surface of the mastoid, vibration levels increased by 10-25 dB compared with when soft tissues covered the point of application. This could be of advantage in bone-conduction ECoG performed at ear surgery.

Acoustic Impedance Tests↗
PubMed1990

The output characteristics of an implanted bone conduction prosthesis.

So far, the published guidelines for patient selection for the Audiant implanted bone conduction device have been derived from clinical trial rather than experimental study. Theoretical considerations suggest that the guidelines should be frequency specific; the need for this was investigated in a laboratory study. Two independent measures of the maximum output of the Audiant device using both the body-worn and ear-level amplifiers have been performed on two subjects. These lead to maximum output figures for the device ranging from 15 dB HL at 250 Hz to 60 dB HL at 6000 Hz for the body-worn amplifier, and from 6 dB HL at 250 Hz to 42 dB HL at 6000 Hz for the ear-level amplifier. These results suggest that the ear-level amplifier is suitable only for candidates with essentially normal bone conduction thresholds at frequencies of 1000 Hz and below.

Adult↗
PubMed1980

A brief communication on bone conduction artefacts.

The various factors which may be involved in the incorrect measurement of bone-conduction threshold are outlined. One of these factors, airborne radiation from the vibrator, has been investigated for three Radioear vibrators, the B70A, B71 and B72. The results indicate that false bone-conduction threshold values could arise, due to the airborne radiation component, mainly with the B72 vibrator.

Audiometry↗
PubMed1993

First clinical experiences with an implantable bone conduction hearing aid at the University of Amsterdam.

A transcutaneous bone-conduction hearing aid was implanted in 11 patients who were not suitable for transcranial sound amplification. Audiological and surgical selection criteria were followed strictly. One device had to be explanted and minor revision surgery was needed in two cases for skin irritation and scarring. In general the aids were well tolerated but the amplification power of the external device proved to be insufficient in some patients, in whom bone conduction levels were on the borderline of the selection limits.

Adolescent↗
PubMed1993

Modification of the traditional bone conduction hearing aid.

The purpose of this technical note is to describe a modification of the traditional bone conduction hearing aid used for the treatment of hearing impairment associated with atresia, microtia, or auditory canal anomalies. This modified unit offers a viable alternative to patients wanting an alternative to the traditional model or an implantable bone conduction aid.

Bone Conduction↗
PubMedDate not supplied

Bone conduction thresholds in patients with otosclerosis.

PURPOSE: Sensorineural hearing loss in patients with otosclerosis is commonly encountered. This study was conducted to determine if surgery on the otosclerotic ear had an effect on the sensorineural hearing. METHODS: A cohort of 262 patients subjected to operation in 311 ears were evaluated. All patients had a minimum of 5 years follow-up and patients over 60 years of age were excluded. Audiograms obtained 1 day before surgery were compared with those obtained 1 year postoperatively and at the last follow-up examination in the study. Results were evaluated using the Student's t test for statistical analysis of hearing results. RESULTS: The mean follow-up was 9.6 years. Deterioration of bone conduction scores occurred in 6.4% of 311 operated ears. Deterioration of bone conduction threshold occurred in the speech frequency in 6 ears (1.9%). CONCLUSIONS: Bone conduction scores of operated ears remained quite stable compared with the otosclerotic ears not subjected to operation. Patients with bilateral otosclerosis may benefit from surgery performed on both ears when indicated.

Adult↗
PubMed1982

Changes in bone conduction thresholds with vibrator contact area.

An experimental bone conduction vibrator was used to measure force and acceleration directly at the point of contact, the subject's forehead. Force and acceleration at threshold were measured for six subjects over a frequency range of 250 to 6000 Hz and over a contact area range of five to one. These measurements suggest that for any test subject, the variation in force of threshold with contact area is much smaller than the corresponding variation in acceleration at threshold.

Audiology↗
PubMedDate not supplied

Bone conduction speech audiometry in normal subjects.

The present study was designed to investigate: (1) the relationship among bone conduction (BC) pure tone averages, BC speech reception thresholds (SRTs), and BC speech detection thresholds for normal subjects; (2) short term reliability of BC SRTs; and (3) characteristics of the articulation functions for spondees obtained by bone conduction. Twenty-five normal-hearing young adults participated. The data revealed that BC SRT-pure tone average and SRT-speech detection threshold relationships are essentially the same as for air conduction. A comparison of the articulation functions for air conduction and BC revealed no practical difference between the two modes of stimulus presentation.

Adult↗
PubMed1994

Clinical applications of transcranial bone conduction attenuation in children.

It is a common belief that there is no significant transcranial attenuation across the skull by bone conduction (BC). In 32 children with proven unilateral sensorineural hearing loss the unmasked bone thresholds were measured on each side. There was a significant attenuation of BC at 4 kHz. Transcranial attenuation of BC at 4 kHz may explain the difference in sound perception between the two ears when bone conduction amplification is used. Further research should be undertaken to identify the better cochlea in mixed hearing losses.

Adolescent↗