Martin Audio Wavefront W8CT, Application Manual

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In this example, high-mid and high frequency air absorption characteristics are
quite complex at low relative humidity. Mid frequency absorption increases with
increasing humidity, reaches maximum attenuation at about 5% RH and then starts to
drop again. High-mid frequency absorption increases with increasing humidity,
reaches maximum attenuation between 5 and 15% RH and then starts to drop again.
High frequency absorption increases with increasing humidity, reaches maximum
attenuation between 15 and 20% RH and then starts to drop again.
At the higher relative humidity (above 20% RH) found in temperate latitudes,
absorption generally decreases with increasing relative humidity. This means that
high frequency sound propagation improves as the relative humidity rises … but this
is not always obvious in warmer weather as our ears produce more secretions when
we perspire.
Note that, even at high relative humidity, we will still loose 10dB at 10KHz over
100m. Martin Audio Wavefront Longthrow systems provide the extra high-mid and
high frequency headroom to cope with this air absorption.
Humidity changes can be a problem indoors too. On rainy days, damp audiences in
large venues can cause temporary humidity increases that can make a well sound-
checked system sound too harsh and fizzy. Be prepared to back off any mid and high
frequency compensation until the venue's air conditioning has caught up.
Longthrow systems should be corrected with caution and distant audience areas
rechecked at regular intervals during large events.
10% 0
0.3dB/m
0.2dB/m
0.1dB/m
0dB/m
Absorption
coefficient
20% 30% 40% 50% 60% 70% 80% 90%
Relative Humidity
10KHz
6KHz
3KHz
1.5KHz
All material © 2007. Martin Audio Ltd. Subject to change without notice.