10
be necessary to either reduce the times used or reduce the ratio
depending upon the effect required.
Modulation
Modulation
If more than about 6db of compression is used, it is desirable to
treat individual sound sources or groups of similar sound
sources separately in order to avoid modulation effects, when a
dominant sound modulates the rest of the signal. It is particularly
difficult to limit low frequency sounds in a final balance, because
the effect on the remaining signal and ambience will be most
noticeable. Separate compression will increase the overall
compression effect.
THE BCL20 AS A LOUDNESS LIMITER
THE BCL20 AS A LOUDNESS LIMITER
The perceived loudness (SPL) is not linear as a function of
frequency. The human ear is more sensitive to the mid-
frequencies than to very low or very high frequencies. This
phenomenon must be taken into account when using a limiter to
control the maximum loudness in certain areas such as
discotheques, clubs and concert halls. To emulate the typical
loss of high and low frequency sensitivity of the human ear, a
weighting filter must be inserted in the side-chain, according to
figureÿ1. This weighting filter is available from a number of
companies manufacturing test equipment. It must be set at "C"
weighting (high levels).
Fig. 1
