Use Of Headphones Research Articles

Multiprocessor 3D sound system

Traditionally, the reproduction of three dimensional audio has been constrained to the use of headphones. Recent progress has allowed the reproduction of 3-D audio through conventional speakers. However, these methods place severe constraints in the position of the listener and the speakers. This paper discusses a new developed system that allows greater freedom in the placement of the speakers without degrading the degree of freedom in the listener's position. It also describes the implementation of a real-time multiprocessor 3-D sound system based on Analog Devices ADSP-2181 processors. A Windows based program is used to control the real-time system using the PC's serial and parallel ports. A 3-D audio system is composed of a binaural spatializer and a crosstalk cancellation. The binaural spatializer allows the placement of virtual sound sources around the listener's head. This is done by convolving the input sound signals with filters that simulate the transmission path from a desired source position in free field to the listeners two ears. The binaural sounds that results from the binaural spatializer are perceived as coming from the desired position, and must be presented using headphones. In order to present binaural sounds using conventional speakers, a crosstalk cancellation system must be used. The crosstalk cancellation system cancels the contribution of each speaker to the opposite side ear (i.e, contribution of left speaker to the right ear). The result is a pair of uncorrelated binaural sound signals, where each speaker only contributes to the same side ear.

Using tubephones for wideband auditory stimulation in brain research

This study was motivated by the need for a high-quality auditory stimulation system for brain research purposes. Magnetic imaging techniques such as functional magnetic resonance imaging (fMRI) and magnetoencephalography (MEG) prevent the use of typical headphones. In fMRI, a high magnetic field does not allow placing magnetic materials inside the imaging system. In MEG, the extremely weak magnetic fields present in the human brain are measured and any magnetic material in the magnetically shielded room would corrupt the results. In these cases, one possible solution is to place electromagnetic transducers outside of the measurement room. Sound has then to be transmitted to the patient’s ears by tubes which produce a highly distorted response. It is shown that by combining acoustical design with analog and digital equalization, wideband flat frequency response is achieved. The design and construction of the apparatus are described and problems like the effect of nonlinear distortion of the transducers are discussed. Practical applications of the system are shown and other possible constructions are compared with the implemented one.

An observational study of protective equipment use among in-line skaters

Objectives—To describe the patterns of protective equipment use by in-line skaters in Winnipeg, Manitoba and nearby rural communities. Methods—In-line skaters were observed for three months in 1996 at 190 urban...

Qualitative evaluations of the acoustics of rooms: Real room studies and headphone studies

This pilot study attempts to qualify the use of headphones to evaluate the listening conditions of existing and proposed architectural spaces. Qualitative listening evaluations of speech and music were conducted in multiple locations in three different listening environments: a 2000-seat multipurpose concert hall, a 600-seat lecture room, and a 120-seat lecture room. Groups of college age students were asked to evaluate loudness, clarity, reverberance, spatial impression, and background noise using a questionnaire with a seven-point bipolar rating scale [Cervone (1990)]. The speech and music sources were played through two adjacent loudspeakers at the front of the respective rooms while the students completed the evaluation forms. The speech and music sources were binaurally recorded on a DAT at the listener locations in the respective rooms. At a later time, students were asked to evaluate the acoustical qualities of the binaural recordings made in the rooms using the same questionnaire. The recordings were presented to the listeners in a random order in a blind subjective evaluation. Data from real room evaluations and headphone studies are compared and conclusions are drawn regarding the potential for headphone listening experiments as a means to study qualitative aspects of room acoustics.

中高校生におけるヘッドホン難聴の存在について

The author has been the school doctor at two junior high schools with a combined student enrollment of 1680, and one senior high school with 959 students.According to the results of a hearing test, three senior high school boys were shown to have hearing loss. All three had been listening to the “Rock music” with 94-100 dB SPL (A) for 2-4 hours a day, for the last 3-5 years. The quantity of noise exposure was sufficient to cause chronic sound trauma judged by my previous TTS2 experiment, etc.It has been more than ten years since the Walkman R has been on the market. Also environmental noise has been increasing. Taking these things into consideration, it will be necessary to consider hearing loss caused by the use of headphones.

Noise-induced hearing loss in randomly selected New York dairy farmers

To understand better the effects of noise levels associated with dairy farming, we randomly selected 49 full-time dairy farmers from an established cohort. Medical and occupational histories were taken and standard audiometric testing was done. Forty-six males (94%) and three females (6%) with a mean age of 43.5 (+/- 13) years and an average of 29.4 (+/- 14) years in farming were tested. Pure Tone Average thresholds (PTA4) at 0.5, 1.0, 2.0, and 3.0 kHz plus High Frequency Average thresholds (HFA3) at 3.0, 4.0, and 6.0 kHz were calculated. Subjects with a loss of greater than or equal to 20 db in either ear were considered abnormal. Eighteen subjects (37%) had abnormal PTA4S and 32 (65%) abnormal HFA3S. The left ear was more severely affected in both groups (p less than or equal to .05, t-test). Significant associations were found between hearing loss and years worked (odds ratio 4.1, r = .53) and age (odds ratio 4.1, r = .59). No association could be found between hearing loss and measles; mumps; previous ear infections; or use of power tools, guns, motorcycles, snowmobiles, or stereo headphones. Our data suggest that among farmers, substantial hearing loss occurs especially in the high-frequency ranges. Presbycusis is an important confounding variable.

Comparing headphone and speaker effects on simulated driving

Twelve persons drove for three hours in an automobile simulator while listening to music at sound level 63dB over stereo headphones during one session and from a dashboard speaker during another session. They were required to steer a mountain highway, maintain a certain indicated speed, shift gears, and respond to occasional hazards. Steering and speed control were dependent on visual cues. The need to shift and the hazards were indicated by sound and vibration effects. With the headphones, the driver's average reaction time for the most complex task presented—shifting gears—was about one-third second longer than with the speaker. The use of headphones did not delay the development of subjective fatigue.

Audio communications module for an office chair

An audio communications system for an office chair provides a user with private listening of RF transmitted audio messages in an exposed environment such as an office area, without the use of headphones. An audio module, which mounts to the backrest of an office chair, includes an RF receiver and a shaped, acoustic horn loudspeaker which directs sound upwardly, behind the user's head, while minimizing lateral dispersion of the sound. In another aspect of the invention, the audio communications system includes a transceiver for two-way communication, such as telephone, and an armrest mounted microphone and keypad.

Noise‐induced hearing loss in randomly selected New York dairy farmers

To understand better the effects of noise levels associated with dairy farming, we randomly selected 49 full-time dairy farmers from an established cohort. Medical and occupational histories were taken and standard audiometric testing was done. Forty-six males (94%) and three females (6%) with a mean age of 43.5 (+/- 13) years and an average of 29.4 (+/- 14) years in farming were tested. Pure Tone Average thresholds (PTA4) at 0.5, 1.0, 2.0, and 3.0 kHz plus High Frequency Average thresholds (HFA3) at 3.0, 4.0, and 6.0 kHz were calculated. Subjects with a loss of greater than or equal to 20 db in either ear were considered abnormal. Eighteen subjects (37%) had abnormal PTA4S and 32 (65%) abnormal HFA3S. The left ear was more severely affected in both groups (p less than or equal to .05, t-test). Significant associations were found between hearing loss and years worked (odds ratio 4.1, r = .53) and age (odds ratio 4.1, r = .59). No association could be found between hearing loss and measles; mumps; previous ear infections; or use of power tools, guns, motorcycles, snowmobiles, or stereo headphones. Our data suggest that among farmers, substantial hearing loss occurs especially in the high-frequency ranges. Presbycusis is an important confounding variable.

Masking‐level differences as a function of masker level: Revisited

Measurement of the masking‐level difference (MLD) has been suggested as a possible test for some types of hearing disorders. When MLDs are measured with hearing impaired patients, careful attention must be paid to the overall stimulus level and differences in sensitivity between the two ears. Studies done in the late 1960s proposed an explanation for the dependence of the magnitude of the MLD on masker level or interaural differences in masker level. This explanation assumes that additive internal noise present in the outer ear produces a significant contribution to the masking stimulus at the low signal frequencies typically used in studies of the MLD. The present paper will review this explanation and combine it with the predictions of the Durlach equalization‐cancellation model of binaural analysis to fit the data from all the studies since 1948 that have investigated the MLD as a function of masker level or interaural masker level. In addition, data from a study using insert headphones will be described. The use of insert headphones, instead of the supra‐aural headphones typically used to measure the MLD, should reduce the contribution to the masker of the additive internal noise present in the outer ear. [Work supported by the Air Force Office of Scientific Research, Life Sciences, and the National Institutes of Health, NINCDS.]

Use of Stereo Headphones for Patient Relaxation During Cataract Surgery Under Local Anesthesia

SUMMARY The use of stereo headphones to provide relaxing background music to patients undergoing cataract surgery under local anesthesia is described. This technique helps to relieve patient anxiety, reduces the amount of sedative medication required, obscures disturbing operating room noise, and facilitates teaching as the surgeon's comments are not allowed to disturb the patient.

Hearing loss and habits of the audiophiles among shipyard workers (author's transl)

It is well known that the occupational hearing loss has very often occurred in the shipyard. Although factors contributing to the occupational hearing loss show a tendency to decrease according to the recent progress of tenchnology, it is reported that young workers in the shipyard having a seght hearing loss show a tendency to increase. It is presumed that this is related to the damage due especially to listening to stereophonic phonograph records in their daily life. Acoustic instruments such as stereophonic phonograph records, radio-cassette recorders, video recorders, and headphones for such acoustic instruments are easily available for daily convenience. They are playing important parts as factors of the daily sound environment. Measured sound levels to which young age groups were exposed in listening to the stereophonic phonograph records were 61 to 78 dB (A) in the case of Japanese songs and 63 to 98 dB (A) in the case of rock and roll music. Hearing losses were measured and the habits of such audiophiles were investigated among 382 workers in a shipyard from March to September in 1977. The results were as follows: 1) The percentage of the audiophiles is 48.6% of the sample subjects. And the younger the age group, the higher this percentage. 2) Difference of the average hearing loss by age group is significant at 1% level. This means that the natural loss of hearing exists as a result of aging. 3) Most of the audiophiles belong to the young age groups, and the average hearing loss of the audiophiles is less than of the non-audiophiles. 4) The average hearing loss of the audiophiles in twenties is less than that of the non-audiophiles in the same age group. 5) Average hearing losses classified both by listening durations and by kinds of chief listening music are not different at 5% level of significance. 6) The relation between the average hearing loss of the audiophiles and the duration of listening to stereophonic phonograph records is not significant. However, the relation between the average hearing loss and the listening frequencies is significant at 1% level. 7) 14.5% of the audiophiles are using headphones. The relation between the average hearing loss and the use of headphones is not significant. From the above facts, the authors consider that hearing loss of the younger age group has not been influenced by the sounds from sterephonic phonograph records under the present state. However, we have to pay attention to acoustic instruments generating sounds in the daily environment. Note: The average hearing loss is expressed in (a+2b+2c+d)/6, where a stands for threshold at 500Hz, b at 1, 000 Hz, c at 2, 000 Hz and d at 4, 000 Hz.

Two Views Toward the Hard-of-Hearing

To the Editor.— An elderly man began having hearing problems, and at 82 years, after consulting with top ear, nose, and throat specialists and an audiologist at a university hospital in a large city, purchased twin hearing aids at the considerable price of $400 each. But that was not the end of the problem. At their best, after repeated adjustments, the hearing aids were useful to this man in a one-to-one conversation, but in a family group he most often resigned himself to isolation—frustrated by trying to hear while intrusive background noises drowned out the meaningful conversation. This summer there was a breakthrough of sorts. I wondered if a relatively simple idea—using ordinary hi-fidelity equipment for communication—might not pay off. Most hi-fi systems allow the use of headphones, and, with a simple adapter, a microphone. As one person talks into the microphone, the other person wears the headphones and adjusts

Some musically oriented acoustics demonstrations

The redundant, though irregular, transmission of sound from source to listener in an ordinary room provides our ears with a large amount of useful information which often permits them to perform far better, in such a room, than one would expect on the basis of psychoacoustic experiments done in anechoic chambers, or by the use of headphones. Some musically oriented illustrations are provided to support this observation.

On the Oscillations of a Circuit Having a Periodically Varying Capacitance

A previous theoretical study of a dissipationless oscillatory circuit having a periodically varying capacity predicted the existence of several interesting types of oscillations. An experimental investigation of such a circuit was therefore made. The results of this investigation are presented in this paper. The dissipation was reduced to a minimum by means of an associated vacuum tube in a regenerative connection. An auxiliary condenser and rotating commutator produced the periodic capacity variation. The nature of the oscillations was studied by means of oscillograph and meter measurements of the currents in the several parts of the circuit and by the use of headphones. A quite good agreement with theory was found, consistent with the deviations of the experimental conditions from the theoretically postulated ones. The oscillations were generally of a complicated nonsinusoidal character, but assumed a substantially sinusoidal form for certain adjustments of the circuit. The frequency of these sinusoidal oscillations was twice that of the capacity variation. Periodic oscillations were found to occur when, approximately, α = 2ω 0 /n, n = 1, 2, 3, ..., where ω 0 is the natural angular velocity of the circuit for the mean capacity value and α is the angular velocity of the capacity variation. Failure of all oscillations for certain circuit adjustments was related to the inherent loss of energy in the switching method employed for varying the capacity. The theory had predicted certain unstable conditions for which the amplitude should increase without limit.