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We reviewed 13 papers on noise exposure of orchestral musicians and found that the question of whether orchestra musicians are overexposed does not appear to have a clear answer. To find relevant papers, we researched three databases (Scholar, Scopos, and Medline), which yielded 6, 9, and 17 papers, respectively (including duplicates). A number of papers in the reviewed literature lacked basic descriptions concerning such issues as measurement technique and instrumentation. Rough data and calculation details were often not provided so that the conclusions could not be checked easily. The most serious problem was the estimated time that musicians performed in the orchestra. This information is crucial for the calculation of the normalized noise exposure levels (L[EX]), and is especially important as orchestra players do not perform year-round nor are they exposed to the same noise levels while performing different pieces of music. [ABSTRACT FROM AUTHOR]

The normal human cochlea is known to exhibit acoustic nonlinearity, observed most easily as a 2f1-f2 distortion product tone in response to two tonal stimuli. This distortion product is physiologically vulnerable, and can be influenced in animals by electrical stimulation of the cochlear efferent nerves. The function of the efferent cochlear innervation is poorly understood but currently revived theory suggests a feedback system may exist between the opposite cochlea, influencing cochlear micromechanics through the outer hair cells [D. O. Kim, Hear. Res. 22, 105-114 (1986)]. The influence of a contralateral acoustic stimulus on cochlear nonlinearity was studied in human subjects through the changes observed in the 2f1-f2 distortion product. The influence of interaural acoustic transmission of the stimulus was controlled by using constant SPL stimuli on subjects with varying degrees of sensorineural hearing loss in the stimulated (contralateral) ear. Results indicate a slight suppression in distortion product with no significant frequency tuning. Strong correlation with middle ear reflex threholds and lack of correlation with sensation level indicate the suppression is not caused by a cochlea-to-cochlea neural mechanism, and is likely caused by the middle ear reflex. [ABSTRACT FROM AUTHOR]

We investigated whether pitch-synchronous neural activity could be recorded in humans, with a natural vowel and a vowel in which the fundamental frequency was suppressed. Small variations of speech periodicity were detected in the evoked responses using a fine structure spectrograph (FSS). A significant response (P < 0.001) was measured in all seven normal subjects even when the fundamental frequency was suppressed, and it very accurately tracked the acoustic pitch contour (normalized mean absolute error < 0.57%). Small variations in speech periodicity, which humans can detect, are therefore available to the perceptual system as pitch-synchronous neural firing. These findings suggest that the measurement of pitch-evoked responses may be a viable tool for objective speech audiometry.

A filterbank-based algorithm for time-varying spectral analysis is proposed. The algorithm, which is an enhanced realization of the conventional spectrogram, consists of hundreds or thousands of highly overlapping wideband filter/detector stages, followed by a peak detector that probes the filter/detector outputs at very short time intervals. Analysis with synthetic modulated signals illustrates how the proposed method demodulates these signals. The resulting spectrogram-like display, referred to as a "fine structure spectrogram," shows the fine structure of the modulations in substantially higher detail than is possible with conventional spectrograms. Error evaluation is performed as a function of various parameters of a single- and two-component synthetic modulated signal, and of parameters of the analysis system. In speech, the fine structure spectrogram can detect small frequency and amplitude modulations in the formants. It also appears to identify additional significant time-frequency components in speech that are not detected by other methods, making it potentially useful in speech processing applications.

A noise exposure survey was performed to assess the risk of hearing loss to school music teachers during the course of their activities. Noise exposure of 18 teachers from 15 schools was measured using noise dosimeters. The equivalent continuous noise level (L(eq)) of each teacher was recorded during single activities (classes) as well as for the entire day, and a normalized 8-hour exposure, termed the noise exposure level (L(ex)) was also computed. The measured L(eq) exceeded the 85-dBA limit for 78% of the teachers. L(ex) exceeded 85 dBA for 39% of the teachers. Limited recommendations on how to reduce the noise exposures are provided. The need for a hearing conservation program has also been emphasized.

A technique for estimating the nonparametric bone conduction transfer function using distortion product otoacoustic emissions (DPOAEs) is presented. Individual transfer functions were obtained using DPOAEs recorded from a single ear of five normal-hearing adults. Repeatability of the technique was investigated by performing measurements on at least three dates. Functions were reasonably repeatable, and were unique to each individual as expected from subjective measurements. Input force and DPOAE measurements were made for each individual, and a model of the auditory periphery representative of an average person was employed. The technique is objective and requires only passive cooperation, but robust DPOAEs are needed and the measurement time can be onerous for a wide frequency band or fine frequency resolution. With appropriate adjustments to the model of the auditory periphery, the method could be applied with animal models.