Bone Conduction Receiver Research Articles

Audiometer receiver and audiometer

An audiometer having an air-conduction receiver, a bone-conduction receiver, a masking receiver and an audiometer body is provided, in which the air-conduction receiver, the bone-conduction receiver, and the masking receiver are respectively provided with serial ROMs in which identification information and calibration information of each receiver are stored. The audiometer body comprises a misconnection detector for detecting misconnection of each receiver, a calibration period judging mechanism for judging a calibration transition period of each receiver, and a correction amount computer for computing a correction amount of sound pressure based on the information stored in the serial ROMs.

気導受話器装着の外耳道内音圧への影響

The effect of wearing of an air conduction receiver on sound pressure in the ear canal was investigated in 22 ears of 11 normal male volunteers. When a bone conduction receiver (Rion BR-41) on the forehead was activated, sound pressure recorded in the ear canal was larger by about 20 dB in all test frequencies than in the auricular conchal cavity or at a place 10 cm from the canal opening. When an air conduction receiver (Rion AD-02) was worn over the auricle, sound pressures in the ear canal and in the auricular conchal cavity increased maximally at 0.8 kHz by 17.9±4.9 dB and 17.7±7.4 dB, respectively. At higher frequencies, however, they decreased in those wearing the receiver.

Identification of voicing contrast via the tactile mode

It has been shown that tactile perception of speech can be categorical along a voice onset time (VOT) continuum and that the boundary between /ga/ and /ka/ occurs at a longer VOT value for tactile than for auditory perception [M. J. Collins and R. R. Hurtig, J. Acoust. Soc. Am. Suppl. 1 75, S33 (1984)]. In that study, a hearing aid with a bone conduction receiver had been used for tactile delivery of speech signals, and the question arose as to the uniqueness of the findings to the velar stop consonant and the specific device employed. The present investigation was designed to determine the consistency of the effect across place for stop consonants and across signal processing and transducer characteristics. An identification paradigm was used to determine the VOT boundary for three processor‐transducer combinations along /ka‐ga/, /ta‐da/, and pa‐ba/ continua. Boundaries fell at similar VOT values for each processor‐transducer condition for velar and alveolar stimuli; complex interactions occurred for bilabials. It was concluded that both tactile system limitations and device characteristics were determinants of VOT boundaries. [Work supported in part by the Spelman Rockefeller Foundation.]

Bone-conduction receiver with an extended frequency range for measuring the threshold of audibility

The present-day standardized threshold audiometry provides a measurement of the audi- tory sensitivity from 0.125 up to 6.0-8.0 kHz. Yet the human ear, as is well known, per- ceives tones of up to 20 kHz frequency, while for bone conduction it responds to sounds up to 200 kHz, i.e., to ultrasounds (1-3). It has been found in practice that an investigation of the audibility thresholds over an extended frequency range (i.e., up to 20 kHz) permits the diagnostic possibilities of audiometry to be considerably enhanced. The diagnostic significance of audibility thresholds at frequencies of I0, 12, 16, and 18 kHz for air-borne sounds was made clear in (4-9). However examinations with air- borne stimuli substantially restrict the diagnostic possibilities of audiometry, even over the extended frequency range because under air-conduction conditions the upper limit of fre- quencies perceived is lowered. It is necessary to develop threshold-measuring methods at frequencies above 8 kHz for bone-conducted sounds. In most cases the detection of early signs of deafness is needed for patients having a symmetrical auditory abnormality (presby- cousis, otosclerosis, the various forms of cochlear neuritis, etc.). Under these conditions it is of paramount importance to develop a bone-conduction receiver that can reproduce sounds of suitable frequencies, and to calibrate the same. The bone-conductor receivers currently used in audiometric practice are of the electro- magnetic type. To a considerable extent this is due to their relatively low electrical im- pedance that permits a receiver to be matched to generating apparatus without the use of special transformers.

"Artificial mastoid" instrument for calibrating bone-conduction receivers over an extended frequency range

"Artificial mastoid" instrument for calibrating bone-conduction receivers over an extended frequency range

Brain Stem Responses Evoked by Bone Conduction Sounds

Short latency responses evoked by bone conduction sounds were recorded from the scalp of humans. One cycle of sinusoidal wave (1KHz)was used as a stimulus for driving the bone conduction receiver. The wave form of the responses evoked by bone conduction sounds was similar to brain stem responses evoked by air conduction sounds.In 10 adults with normal hearing, the thresholds of the bone-conduction BSR were 5 to 15dB SL (sensation level). In 7 normal hearing children, the bone-conduction BSR thresholds ranged from 0 to 20dB nHL (the mean of the sensation level of 10 normal hearing adults).The bone-conduction BSR test was applied to 20 clinical patients with conductive, scnsorineural and mixed hearing losses. It was demonstrated that the bone-conduction BSR test was useful for differentiation of conductive, sensorineural and mixed hearing losses.

A Holographic Study of the Human Skull Vibration

Vibration mode of the human skull was studied by means of holographic interferometry. Three dry human skulls were vibrated with generated bone-conduction receiver for several test frequencies within audible range.After assessing resonance frequencies on each skull, holograms of the vibrating skull were recorded and reconstructed in each resonance frequency principally.Vibration of the skull was clearly discernible not only at the vibrated temporal surface but also the opposite side.Noteworthy findings were vibration fringes on the temporal surface observed at the test frequencies of 400Hz and 100Hz, suggesting a possible component of compression bone-conduction at such low frequency ranges.

Audiodontics-a case report.

Abstract A case is presented of a young boy with bilateral conductive deafness secondary to bilateral microtia. His ability to hear by means of a bone conduction receiver held between the teeth is a practical demonstration of ‘audiodontics’.

Recruitment im kalibrierten Weber-Test nach Stapedektomie

The function of the internal ear after a stapedectomy is controlled by lateralization to the operated ear using the Weber's hearing test. A shift of lateralization to the other ear indicates a decrease in the bone conduction. A recruitment of the operated ear is proved by a retrograde lateralization when striking the tuning-fork strongly. The quantitative evaluation of the recruitment in the “calibrated Weber's hearing test” using an audiometer and placing the bone-conduction receiver on the forehead, gives evidence of the post-operative internal ear function. This quantitative evaluation is obtained by determining the exact sound level in shifting the lateralization. The results obtained from tests made on 50 stapedectomized patients showed a decrease in the hearing ability of the operated ear, reaching a maximum on the 4th to the 6th postoperative day. The degree and the duration of the recruitment, and therewith of the internal ear damage are indicative of the final bone conduction threshold.

Electronic calibration of bone-conduction receivers.

THE IMPORTANCE of routine calibration of earphones and bone-conduction receivers used with audiometers cannot be too highly emphasized. Otherwise, it is impossible: (1) to know whether thresholds of patients are contaminated by faulty equipment; (2) to know whether apparent changes in hearing over time for a patient are due to true differences in his performance or to variations in the equipment; and (3) to accurately compare results obtained in one clinic or laboratory with those found in another clinic or laboratory. <h3>Earphone Calibration</h3> The methods of calibrating earphones have been fairly well established and reported in the literature.^1-3Several types of artificial ears are available commercially for calibrating earphones. In our laboratory, we prefer an artificial ear complement (Bruel &amp; Kjaer) consisting of a standard artificial ear and 6 cc coupler, condensor microphone, and spectrometer, which enables us to determine the performance of audiometers or earphones and to note

Hearing test for conductive deafness

test has become important for tympanoplasty because it indicates the location of lesion and predicts postoperative hearing. However the basic knowledge has not yet been accumulated enough to establish this method. Therefore, the author measured the mechanical characteristics of a nylon which was attached to a bone conduction receiver. It was found that this Sonde was hardly influenced by the pressure when it was pressed on the subject's ear drum, Moreover, this Sonde had no appreciabie amolitude distortion. Then the author carried out hearing test using this Sonde in 136 cases of conductive deafness. This Sonde was proved to be available in clinical use because of little pain in its application to the ear drum. Hearing loss measured by the Sonde corre- sponded with air conduction loss in cases of oto- sclerosis and pseudo-otosclerosis in which the mobi- lity of the ossicular chain was affected. On the other hand, hearing loss measured by the Sonde did not always correspond with air conduction loss in adhesive otitis, cholesteatoma otitis, and chronic suppurative otitis. This fact depended upon whe- ther the mobility of the ossicular chain was affe- cted in these cases or not. When the ossicular chain was intact in mobility, no hearing loss was detected by the Sonde and vice versa. Therefore, when hearing loss by the Sonde was more than 20 dB, it was diagnosed as the disorders of the ossi- cular chain. But when hearing loss was within 20 dB, the ossicular chain was regarded as intact or as of the type of continuity by the connective tissue. In this case liquid-conduction test and the test using the artificial ear drum should be applied to confirm the diagnosis made by Schallsonde test'

PROBLEMS CONCERNING THE BONE CONDUCTION TESTS.

After limiting the air conduction threshold one bone conduction receiver is placed at the front of the tested person. Double contralateral masking: an olive of the rubber tube, connected with Barany's box is tightly fitted to the external meatus and to the mastoid bone, is placed an oscillating vulcanite adapter connected with this box by a bifurcate metalic tube. Audiometric bone conducting tests are performed in the interrupted form eliminating the across-head difference. Fifteen cases of different impairments of hearing, bone conduction Gelle, Wheatstone-Bing, Runge tests and the crossed hearing of bone perception in two cases of congenital deafness are discussed.

Clinical application of hearing tests.

This presentation is to illustrate by typical examples the clinical evaluation of masking, recruitment, and adaptation. Masking Our experience with white-noise, narrow-band, and pure-tone masking indicates that of these, narrow-band masking is the most efficient. Narrow-band noise produces about 10 db. more masking effect than white noise at equal over-all intensity levels. Presentation of the masking signal may be by conventional phone, insert receiver, or bone conduction receiver. The insert receiver has the advantage of permitting greater intensities without producing cross

A basic study on bone conduction audiometry

All measurement was done on forty three patients with unilateral nerve deafness under clinical condition.1. Test-retest variation:Both tests were carried out by the same observer (author) with the same apparatus at the interval of twenty to forty minutes.In order to investigate the cause of the test-retest variation, the variations obtained with three different types of bone conduction receivers and an air conduction receiver were compared.This revealed that inconsistency in physical value of the auditory stimulus due to unstable fixation of the instruments had most contributed to the test-retest variation.2. Points of receiver application:A receiver placed on the mastoid process gave a better sensisitivity by ten decibels than that placed on the middle forehead. No statistical significance was found in individual variation in either case.Therefore, fixation on the mastoid process is considered to be better.3. Interaural acoustic attenuation:The average interaural acoustic attenuation was six to twelve decibels, although this range wassubject to change with test frequency. Each measured value, however, ranged much wider.In order to decide which ear has better bone conduction, therefore, it is essential to pay attention to the relative position of the threshold curves of both ears on the whole.

Masking in audiometry. III. Reflections upon the present position.

The rules governing the use of masking in air and bone conduction audio-metry are discussed and the situations leading to cross-hearing are presented. The advantages and disadvantages of the bone conduction masking procedure (Rainville) are considered. The authors at present prefer a frontal placement of the bone conduction receiver, the masking noise being led to the ear by an ear canal insert. The latter increases the interaural attenuation by 15 to 20 db and thus facilitates bone conduction audiometry.

Clinical calibration of bone-conduction measurements.

Since the advent of pure-tone audiometry it has been recognized that measurements of threshold by bone conduction may not be entirely dependable. Uniform standards have not been established for the calibration of bone oscillators, and therefore the results obtained in bone-conduction tests are purely relative. In 1931 Knudsen and Jones¹felt that it would be desirable to express the results of bone-conduction tests in absolute units as was done in measurements by air conduction. They concluded, however, that the methods known to them did not permit such absolute measurement of hearing by bone conduction. Despite this difficulty, they considered the testing of bone conduction by electric apparatus to be significant and valuable. In 1936 a committee on methods of testing hearing by bone conduction outlined the difficulties of bone-conduction audiometry as compared with air-conduction testing.²The committee reported that there was no assurance that bone-conduction receivers would hold

HEARING TEST IN YOUNG CHILDREN

Although hearing test in the young children is quite difficult, the author believes that one of the namely, making the children hear an easy word recorded in a loud voice and small voice and have him .repeat the same word, is quite simple and effective. Therefore, the author studied this method and obtained the following results. 1, Two syllabic words are used for the hearing test, and they are classified into two kinds. One is composed of two monosyllables, each of which is easy to hear, and the other is easy to hear two syllabic word, both of the words being well known to the children. In the hearing tests using these two groups of words no significant differences can be recognized in the results. In the final analysis, easy words that the young children know well are most appropriate for the hearing test. 2.. Employing this method on 299 children of the age ranging from two to eight years having difficulty with the audiometer test, the hearing test has been done satisfactorily in more than 90 per cent of them. 3. Those who failed to respond to the test were mostly those supposedly to have perceptive disease with a relatively significant hearing loss. they will show no fear for the test. 5. In the author's experience, even a very young children showed no displeasure in using a receiver. 6. In the application of this method for the group test on the primary school pupils, When they were asked to write down the words spoken to them, many failed to write down the words even in children above the second grade. However, when they were made to repeat these words, even in first grade pupils the test had been satisfactory. 7. This method when employed with a superior bone conduction receiver, can be useful even for bone conduction test.

Clinical bone-conduction audiometry; the use of a frontally applied bone-conduction receiver and the importance of the occlusion effect in clinical bone-conduction audiometry.

General Considerations Many otologists and audiologists, while having considerable confidence in methods of testing hearing by air conduction, have little confidence in bone-conduction tests carried out in the time-honored fashion with a bone-conduction receiver applied first to one and then to the other mastoid process. Many believe that bone-conduction testing has some value as a supplement to the classical tuning-fork tests, but that it lacks any useful degree of precision and must be allowed to serve only as an approximate guide to the nature, rather than an accurate measure, of a hearing impairment. One reason for this belief may be the observation that bone-conduction test results are evidently more readily influenced by a number of variable and extraneous factors than are air-conduction tests of hearing requiring the use of a pair of air-conduction receivers. The efficiency of bone-conduction hearing is, for example, influenced to a considerable degree by the position

The location on the skull of a bone conduction receiver and the lateralization of the sound impression.

During examination of patients, having normal ears in all respects, it was often observed that a tuning fork placed on top of the skull but outside the midline was heard with the contralateral ear and not, as one might expect, with the ipsilateral ear.In normal test persons a tuning fork placed on top of the skull. outside the midline may be heard, depending on place and frequency, in the contralateral ear. This phenomenon was investigated by placing a bone conduction receiver along an adhesive strip attached to the head of the observer running from one ear over the top of the skull to the other ear.For frequencies around 500 cps there was one region on each side of the skull where placing of the receiver gives lateralization of the tone to the contralateral ear. For frequencies around 1200 cps there is on each side of the skull a region with lateralization to the ipsilateral side and one with lateralization to the contralateral side.It could be demonstrated that these lateralization impressions are due t...

The mechanical impedance of the human mastoid process

At the instance of the Electro-Acoustics Committee of the Medical Research Council, the National Physical Laboratory has undertaken a comprehensive series of measurements of the driving-point impedance of the process of the head on twenty normal subjects for a variety of operating conditions. The main object of the work was to develop objective procedures for assessing the response characteristics of bone-conduction receivers, by providing data for the design of an artificial mastoid having a driving-point impedance simulating the average human mastoid. The design of such a device is in hand and will be reported in due course. A frequency range of 125-6200 c/s was covered which is rather wider than that currently utilized in hearing aids or audiometers operating by bone conduction. In the frequency band concerned the impedance of the average was found to be expressible simply as the impedance of the tissue layer backed by a rigid mass representing the inertia of the whole head. Equivalent electrical networks derived from the test results illustrate the dynamical properties of the system and their dependence on operating conditions such as the static contact force and the driven area. A short review of the small amount of comparable data reported by other authors is included.