Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Bone Conduction”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 19 recordsLinked to original sources
PubMed1977

Calibration force levels for bone conduction vibrators.

Two bone conduction vibrators (Radioear B71 and B72) and a headband (Radioear P-3333) have been developed to meet specifications of both the International Electrotechnical Commission and the American National Standard Institute. Pure-tone thresholds for air conduction and bone conduction were obtained from 24 normal-hearing young adults at audiometric frequencies between 250 and 4000 Hz. Results of this study are in good agreement with the standard air conduction threshold sound pressure levels (ANSI) and with bone conduction threshold force levels reported in the literature.

Adult↗
PubMed1978

Audiometric bone conduction.

Audiometric bone conduction test data are obtained with a unit that permits comparison with a recognized standard because the unit can be calibrated to operate within specified limits. Proper calibration of the unit is necessary if the equipment is to be accurate. Two procedures can be helpful in determining the need for calibration: the average loss method and the input voltage measurement method. Neither should supplant calibration, but each offers a means of checking the output of the unit. Confidence in auditory test data is increased when there is a high degree of consistency among the various tests; the availability of several different tests in the audiometric series can be used to an advantage then in a determination of consistency. An additional opportunity to ascertain the existence of consistency is present when tuning fork tests are employed as part of the total evaluation. The use of a masking stimulus in the nontest ear simultaneously with the presentation of the test tone to the test ear can be extremely useful in defining the type as well as the extent of the hearing loss. Presentation of the test tone and the masking stimulus in controlled discrete steps is the key to the interpretation of masking results.

Acoustic Stimulation↗
PubMed1979

Auditory brain stem evoked responses to bone-conducted signals.

Auditory brain stem evoked responses to air-conducted and bone-conducted signals were recorded in subjects with normal hearing and in subjects with conductive hearing loss. In normal subjects, the latency to wave V for bone-conducted signals was approximately 0.5 ms longer than the latency for air-conducted signals delivered at the same sensation level. In conductive hearing loss, the separation of the latency-intensity functions for air conduction and bone conduction (corrected for the 0.5-ms delay) provided a valid estimate of the behavioral air-bone gap in the 1,000- to 4,000-Hz region.

Audiometry, Evoked Response↗
PubMed1976

Early bone conduction hearing aid devices.

The concept of bone conduction hearing is old. By the 16th century the conduction of sound by a rod or the staff of a spear was reported by a number of writers; however, these writers considered these phenomena as a curiosity rather than having practical value. In the 17th century, John Bulwer and George Sibscota, both interested in the deaf and their education, applied the bone conduction phenomenon as an aid to defective hearing. Soon, independent reports from Germany, France, and Italy also described bone conduction rod devices as aids to impaired hearing. In 1879, the Audiphone, a hearing fan that operated by bone conduction, was patented. The invention of the Audiphone triggered the development and sale of a number of similar devices that had considerable popularity until the invention of the carbon-electric hearing aid in the early 1900s.

Bone Conduction↗
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↗
PubMed1979

Bone conduction calibration: current status.

Attempts to specify normal threshold sensitivity by bone conduction have been unsuccessful because of problems in obtaining reliable measurements from commercially available artificial mastoids. Recent design modifications incorporated in the Bruel and Kjaer 4930 artificial mastoids have resulted in greater uniformity among these units. However, the new design has resulted in impedances that are higher than those recommended in current standards. Bone-conduction thresholds referenced to measurements made on B & K 4930 artificial mastoids with the new design were performed on 60 normal listeners by three participating laboratories. The results are reported for consideration in the development of a reference threshold for hearing by bone conduction.

Acoustic Impedance Tests↗
PubMedDate not supplied

Comments on the acoustic-reflex response for bone-conducted signals.

Previous studies which have measured acoustic-reflex responses to bone-conducted signals have not effectively differentiated reflex responses from artifacts. A convenient method for identifying such artifacts was developed and employed on some acoustic-reflex measures for bone-conducted signals. The findings indicated that artifacts result when a frequently-used acoustic admittance meter (Grason-Stadler 1720B) and a conventional bone vibrator were used to measure reflex responses for tonal and noise-activating signals. It was suggested that the method be employed in future studies which investigate the acoustic reflex in response to bone-conducted signals.

Acoustic Impedance Tests↗
PubMedDate not supplied

Clinical implications in calibration requirements in bone conduction standardisation.

Although international agreement has long been reached on a standard threshold for air conduction audiometry, no similar standard exists for bone conduction autiometry. It is argued that the techniques applied to the determination of the air conduction thresholds are not applicable to those for bone conduction which should instead be brought into line with ISO 1964 and not established independently. A pilot study has been carried out which shows that by adopting the new approach now advocated international agreement could be attained with the expenditure of minimal time and effort.

Acoustic Stimulation↗
PubMedDate not supplied

Occlusion effect: bone conduction speech audiometry using forehead and mastoid placement.

The occlusion effect (OE) was determined for bone conduction speech reception thresholds (SRTs) in 24 normally hearing subjects using forehead and mastoid placement. Results indicated that the OE was about 3 dB greater using forehead as opposed to mastoid placement. The intersubject variability of the OE is similar for the forehead and mastoid positions. The formula for effective masking for bone conduction speech should be equal to the minimum masking level for bone conduction speech plus the air-bone gap of the nontest ear plus 18 dB to account for the OE when using mastoid placement.

Acoustic Stimulation↗
PubMed1992

[Masking in bone-conduction testing--proposal of ABC method].

A new strategic masking technique, namely the ABC method, has been developed. In performing this method of measuring thresholds of bone-conduction, the vibrator is placed at the forehead with both ears occluded by air-conduction earphones. One of the earphones is for masking noise and the other is a dummy which balances out the occlusive effect of the test ear against the nontest ear. The ABC method is based on the ABC rule that, in bone-conduction testing, the effective masking noise level necessary to block out the nontest ear can be calculated by a simple equation: right AC (A) + left AC (B)--unmasked BCu (C) under the assumption that the BCu belongs to the nontest ear. In some cases of hearing loss, the above noise level might produce overmasking, then an additive safety noise level, BCu + Interaural Attenuation, is employed. This method offers testers step by step directions which consist of indications of the noise level and a criterion for determining whether the measured bone-conduction is free from cross hearing and overmasking for the given configuration of air-conduction of both ears, BCu, and the masking noise level. Compared to the well known Plato method, in which measurements of thresholds are repeated at several masking noise levels in order to find a single bone-conduction threshold, the ABC method can essentially find the threshold at only one masking noise level. Therefore the ABC method makes it possible to save a great deal of time in performing bone conduction testing.

Audiometry↗
PubMed1977

[Bone conduction changes in secretory otitis media (author's transl)].

In serous and secretory otitis media a reduction of bone conduction frequently exists besides the loss of air conduction. In 304 audiograms of ears with serous and viscous fluid in the middle ear there was a depression of the bone conduction between 15 and 40 dB in 40%. This bone conduction loss was reversible after the aeration of the tympanic cavity. That means that we deal with a false nerve deafness in many of these cases.

Bone Conduction↗
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↗
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↗
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↗
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↗
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↗
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↗
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↗