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Information about the graduation research project: Binaural Noise Exposure from Direct Sound of the Own Instrument


Background: Given the complexity of orchestral noise, assessment of sound exposure to symphony orchestra musicians by means of noise dosimetry is limited. More insight in the individual sound exposure may be obtained by means of a sound level prediction model. In a model proposed by Wenmaekers, the direct sound exposure to one’s own instrument may be estimated using the free field directivity and sound power level for a short distance between the instrument and the musician’s ear. The objective of this study is to measure the direct binaural sound level of the own instrument for typical symphony orchestra musicians. In addition, the direct binaural sound exposure is compared to the calculated sound exposure according to Wenmaeker’s model.

Method: The direct binaural sound level of the own instrument is measured with two miniature condenser microphones fixed to the musician’s ears. In a feasibility study, the frequency spectrum of these microphones is compared to a standardized microphone by means of sound level measurements. Then, a comparison is made between sound exposure measurements with a miniature microphone fixed to the ear of a head-and-torso simulator and a standardized microphone above the shoulder of the head-and-torso simulator (the latter according to ISO 9612:2009). The direct binaural sound level of the own instrument is individually measured for 5 musicians (with a total of 9 instruments) in an anechoic chamber.

Results: The sound levels measured by the miniature microphones exceed the levels from the reference microphone with more than 1 dB for frequencies above the 3150 Hz 1/3 octave band. The comparative sound exposure measurement shows higher sound levels for the microphone fixed to the ear between 2 – 8 kHz, indicating an increased sensitivity. All binaural sound levels exceed 85 dB(A). The highest sound levels are found at the trumpet - / flugelhorn player’s ears, i.e. 97 – 99 dB(A). The flute player’s right ear was exposed to about 5 dB(A) higher levels than the left ear, the trombone player’s left ear was exposed to 5 dB(A) higher sound levels than the right ear and the violin player’s left ear was exposed to about 3 dB(A) higher sound levels than the right ear. Calculations of the direct sound level of the own instrument using Wenmaekers’s model result in underestimated sound levels for the flute, trombone and violin. In addition, the model does not consider possibilities of binaural asymmetry. A justification of the angles and distances improves the model and results to hardly any differences between binaural measured sound levels and calculated sound levels.

Conclusions: Sound level measurements with the miniature microphones used in this study should be adjusted for frequency spectrum. Binaural measurements of sound exposure to sound exposure and measurements according to ISO 9612:2009, should not be compared directly. Sound levels resulting from the direct sound of one’s own instrument are potentially hazardous and may result in hearing loss. The binaural measurements provide a valuable insight in the sound exposure per musician’s ear. Wenmaekers’s model seems to be appropriate for the determination of the direct sound exposure of the own instrument, provided that the chosen distances and angles are justified.

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