9320 Reference Controller Operating Manual 40 (52)
8.8.1 How 9320 obtains exposure
The 9320 can continually measure the sound level at the listening position or estimate the sound level at
the ears when using headphones. Using the continuous evaluation of the sound level at the listening
position and the exchange rate information, the 9320 noise dose calculator continually accumulates the
sound exposure (noise dose), and this is useful for understaing the safe exposure and hearing health
risk in media work.
When the measurement microphone is used, a complete noise exposure can be measured such that the
measurement contains the effect of all noise at the listening location, not only the effect of the audio
content playback.
In order to obtain an accurate noise dose assessment for a mixing engineer, place the measurement
microphone permanently in the vicinity of the listening location, for example by hanging the microphone
in the ceiling above or close to the engineering position.
For headphones, the estimation is done using the input signal, and the noise dose calculation indicates
the impact of the audio content playback, alone. The headphone sensitivity setting is available in the
GLM configuration for the 9320. For very accurate estimation of the listening SPL when using
heapdhones, this figure should be set using a reference sound level measurement at the ears when
using the headphones. If the headphone sensitivity is set using a headphone’s data sheet nominal
sensitivity, the sound level estimation may not be accurate in all cases. In calculatin of the dose, the sum
of the left and right channel content is condered. When the headphone sensitivity data is missing, the
headphone audio does not contribute to the sound exposure accumulation.
Fig. 34. Setting for the headphone sensitivity.
Fig. 35. Inputs to the sound exposure support both the microphone SPL measurement and
measurement at the audio source.
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