Installing SoundStructure Devices
8 - 11
The following figure shows examples of peak signal levels that are too low,
just right, and too high during normal conversational speech at the desired
distance from the microphone.
If the meter levels are too low for a given microphone and for the desired dis-
tance from the microphone, increase the input gain slider to add more gain to
the signal in the analog domain. As a starting point for adjusting gains, con-
sider the following table that lists microphone sensitivities with the analog
input gain required to create a 0 dBu nominal signal level in the SoundStruc-
ture products assuming a 72dB SPL audio signal at the microphone. The
sensitivity information includes both dBV/Pa and mV/Pa formats and the
microphone gains in this table have been rounded to the nearest 0.5dB.
SoundStructure devices provide up to 64dB of analog gain to support micro-
phones with sensitivities as low as -44 dBV/Pa (or 6.3 mV/Pa). Microphones
that have a lower sensitivity may require additional external signal gain to
provide enough gain to get to the 0 dBu nominal signal level. A microphone
with higher sensitivity means that less gain is required to achieve a 0dBu nom-
inal signal when a 72dB SPL signal is present at the microphone.
For example, a common tabletop microphone has a sensitivity of -27.5
dBV/Pa. which translates to an input gain of 48dB.
Sensitivity (dBV/Pa) Microphone gain (dB) Sensitivity (mV/Pa)
-50.0 70.0 3.2
-48.0 68.0 4.0
-46.0 66.0 5.0
-44.0 64.0 6.3
-42.0 62.0 7.9
-40.0 60.0 10.0
-38.0 58.0 12.6
-36.0 56.0 15.8
-34.0 54.0 20
-32.0 52.0 25.1
-30.0 50.0 31.6
-28.0 48.0 39.8
-26.0 46.0 50.1
-24.0 44.0 63.1
-22.0 42.0 79.4
-20.0 40.0 100.0
Bad
(Too Low)
Good Bad
(Too High)
-20
-16
-12
-8
-4
0
4
8
12
16
+20
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