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Results for “Bone Conduction”

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At least 145 records · Page 8Linked to original sources

PubMed2007

Vestibular-evoked myogenic potentials in patients with otosclerosis using air- and bone-conducted tone-burst stimulation.

OBJECTIVE: Otosclerosis is a progressive disease with a remodeling process causing ossicular malformation and conductive hearing loss. The aim of this study was to investigate whether vestibular-evoked myogenic potential (VEMP) correlates with the progression of otosclerosis. DESIGN: Fifteen patients with otosclerosis (21 ears) without operation and 10 healthy subjects (20 ears) underwent VEMP test using air-conducted (AC) and bone-conducted (BC) tone-burst stimulation. SETTING: Tertiary referral university hospital. RESULTS: In 21 unoperated otosclerotic ears, 5 ears (24%) showed present AC-VEMPs, and 16 ears had absent AC-VEMPs. Conversely, 16 ears (76%) displayed present BC-VEMPs and 5 ears with absent BC-VEMPs. In those with both AC- and BC-VEMPs, none of them showed air-bone gap greater than 30 dB; in those with absent AC-VEMPs but present BC-VEMPs, 27% of the ears had air-bone gap greater than 30 dB; and in those with absence of both AC- and BC-VEMPs, 80% of the ears revealed air-bone gap greater than 30 dB. Thus, a significant relationship existed among the presence of AC-VEMPs, BC-VEMPs, and magnitude of conductive hearing loss. CONCLUSION: The presence of an AC-VEMP may indicate an earlier stage of otosclerosis, although absent BC-VEMP infers a later stage. Restated, AC-VEMPs may complement the results obtained with BC-VEMPs to classify the stage of otosclerosis.

Acoustic Stimulation↗

PubMed2002

Effect of stimulus duration for bone-conducted ultrasound on N1m in man.

Ultrasound can be heard by bone conduction in man. However, there has been no consensus about the perception mechanism of bone-conducted ultrasound (BCU). In the current study, to clarify the central auditory system of BCU, the effects of stimulus duration for 30 kHz BCU on N1m were compared with those for air-conducted 1 kHz tone bursts by magnetoencephalography. As a result, the growth of N1m amplitude for both stimuli saturated at the duration of 40 ms, which suggest that the temporal integration system of BCU is similar to that of audible sound. However, significant differences in the growth were observed below the saturation points. The results indicate a possibility that there are some differences in the central auditory system between BCU and audible sound.

Acoustic Stimulation↗

PubMed2002

Sound stimulation via bone conduction for tinnitus relief: a pilot study.

For some patients suffering from tinnitus, an external sound stimulator can offer some mitigation. Based on our positive experience with the bone-anchored hearing aid (BAHA), it seems possible to transmit a masking or habituating sound via bone conduction. A potential advantage of bone-conducted sound is that it is transmitted to the cochlea without affecting the normal hearing via the external and middle ear. The present pilot study, on patients who use a conventional BAHA and who experience mild-to-moderate tinnitus, shows that bone-conducted sound has the potential to relieve tinnitus in the same way as air-conducted sound. It was also found that these patients, having a significant conduction hearing loss, required conventional sound amplification via a BAHA simultaneously with the stimulus provided by the bone-anchored sound stimulator (BASS). Further studies on patients with more severe tinnitus must be conducted in order to justify the use of a BASS for tinnitus relief.

Acoustic Stimulation↗

PubMedDate not supplied

Bone-conduction masking for threshold assessment in auditory brain stem response testing.

The viability of applying Sensorineural Acuity Level (SAL) audiometry to auditory brain stem response (ABR) testing was investigated using 38 subjects with normal hearing, conductive, sensorineural, and mixed hearing losses. The stimuli were clicks, 4000, 2000, and 1000 Hz tone-pips. After ABR thresholds (ABRt) were obtained, bone-conducted noise was used to mask the response to a stimulus 5 dB above ABR threshold (ABRt + 5). Estimates of behavioral bone-conduction thresholds were made by observing the amount of noise needed to mask ABRt + 5. Estimates of behavioral air-conduction thresholds were based upon ABRt. Results indicated that ABRt was within +/- 10 dB of behavioral air-conduction threshold across subject groups at least 74% of the time for all tone-pip stimuli. ABRt was within +/- 15 dB of the pure-tone average of 1000, 2000, and 4000 Hz 75% of the time when click stimuli were used. Derived bone-conduction thresholds were within +/- 10 dB of the actual bone-conduction threshold at least 73% of the time for all stimuli. It was concluded that, when used in a conservative manner, the application of SAL audiometry to ABR testing may increase the reliability and confidence with which decisions are made concerning the type and degree of hearing loss in difficult-to-test patients.

Adult↗

PubMed2003

Time-intensity trade of bilaterally bone-conducted sounds in normal hearing subjects.

OBJECTIVE AND METHODS: In an effort to examine the rules by which information of bilaterally applied bone-conducted signals arising from interaural time differences (ITD) and interaural intensity differences (IID) is combined, data were measured for continuous 500 Hz narrow-band noise at 60 dBHL in 30 normal-hearing subjects using a centering method. Time-intensity trading functions were obtained by means of a sound image shifted towards one side by presenting an ITD, and shifted back to a centered sound image by varying the IID in the same ear. ITD values were varied from -600 to +600 microseconds at 200 microseconds steps, where negative values indicate delays to the right ear. RESULTS: Time-intensity trading functions in response to bone-conducted signals showed significantly lower discrimination thresholds across IIDs, when compared to a control group with applied air-conducted signals. These findings can be interpreted as a constructive interference effect related to the intimate mechanism of bilateral bone conduction, where interaural time differences play a major role. CONCLUSION: Time-intensity trade of bilaterally bone-conducted sounds in normal-hearing subjects is the highly sensitive. The high speed of sound through the skull may be the main reason for the high sensitivity of time-intensity trading.

Adult↗

PubMed1978

Physical and physiological constraints on the use of bone-conduction speech audiometry.

Several authors have recommended the use of bone-conduction speech audiometry, and the literature supports the clinical value of this procedure. It has been claimed that bone-conduction output for speech can be increased to 110-dB HL with the Radioear B-70-A vibrator through supplementary amplification, but this claim is unsubstantiated by objective measurements. Available technical data indicate that the maximum output level attainable with this virbator without incurring serious distortion is 65- to 70-dB HL at midfrequencies and substantially less at lower frequencies. Both behavioral and electromechanical data are presented which show, not only that 70-dB HL is the absolute maximum hearing level for speech attainable through the B-70-A vibrator without serious deterioration of speech-discrimination scores in normal listeners, but also that this appears to be very close to the maximum vibratory level that human observers can comfortably tolerate.

Audiometry↗

PubMed1986

The use of acoustical test fixtures for the measurement of hearing protector attenuation. Part II: Modeling the external ear, simulating bone conduction, and comparing test fixture and real-ear data.

This paper investigates two main features of the human head which influence the measured attenuation of circumaural and intraaural hearing protection devices (HPDs): the external ear and the different pathways of bone conduction. A theoretical model for the external ear shows that its influence on the insertion loss of HPDs, on the sensitivity level of headphones or earphones, and on the insertion gain of hearing aids, all can be described by one equation. While it is not necessary to simulate the eardrum impedance in order to measure the insertion loss of earmuffs and the sensitivity level of headphones with acoustical test fixtures (ATFs), the required accuracy of an ear simulator is more stringent when the same measurements are performed on intraaural devices. For the evaluation of HPDs, bone conduction plays an important role. We have developed a model to estimate HPD-dependent bone conduction effects. The model includes two bone conduction sources: one in the external ear and one in the middle ear. The model explains, for example, the occlusion effect of HPDs and the masking error at low frequencies due to physiological noise that arises when real-ear attenuation at threshold (REAT) measurements are made. Consequently, objectively measured insertion loss can now be used to predict REAT with improved accuracy. ATF and REAT data are compared using nine earmuffs and nine earplugs. In the majority of cases, the two sets of data agree well. Discrepancies are discussed.

Auditory Threshold↗

PubMedDate not supplied

The middle ear inertial component of bone-conduction hearing in man.

The middle ear inertial component of bone-conduction hearing was studied in 8 normal-hearing young adults. The inertial component was eliminated to varying degrees by introducing various positive and negative air pressures into the ear canal. Sweep-frequency Békésy tracings were obtained from 100 through 5 000 Hz for bone-conducted pure tone stimuli while the air pressure of the test ear was varied and the nontest ear was masked. Air pressures of +/- 100, +/- 300, and +/- 500 mm H2O were utilized. Results revealed maximal shift in the mid frequencies (750 Hz) and an increase in effect with increase in pressure. A second prominent region of threshold shift emerged at 2 000 Hz for the +/- 500 mm H2O air pressure conditions. Considerable variability in the magnitude of threshold shift and in the frequency region of maximum shift was observed.

Acoustic Stimulation↗

PubMed1994

Myringoplasty. A conventional and extended high-frequency, air- and bone-conduction audiometric study.

Comparison of the pre- and postoperative air- and bone-conduction thresholds in 22 subjects in whom successful myringoplasty was performed has been made in the conventional and extended high-frequency ranges. Air-conduction thresholds improved through 4 kHz, but were elevated postoperatively for the frequencies 6 through 18 kHz. Postoperative bone-conduction thresholds were elevated at 0.25 and 0.5 kHz, were lower by 2-8 dB for 1 through 3 kHz and not significantly altered in the extended high-frequency range of 8 through 16 kHz. The extended high-frequency air-conduction threshold loss following myringoplasty in this study is, therefore, due to changes in middle ear transmission and is not indicative of iatrogenic cochlear damage.

Acoustic Stimulation↗

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↗