[CM] audio leveler

Russell L. Harris rlharris@broadcaster.org
Sun, 13 Aug 2006 17:38:04 -0500

Is this the correct list for inquiries concerning SND?

I have need of an audio "leveler", alternatively known as an "automatic
gain control".  It occurs to me that a software approach might be
superior to the use of hardware.

My specific application is production of audio material -- primarily
the spoken word -- for use on audio cassettes, audio CDs, and MP3
players in an automobile.  

The normal dynamic range of a high-fidelity recording of a class or
other audio presentation is too wide for this environment: if the audio
level on the playback device is adjusted so that loud passages are not
painful to the ear, then low passages are lost in the noise of the road,
wind, and traffic.

A wide variety of hardware audio compressors is available, but the only
way which I see to make use of a compressor is to use a high compression
ratio (10:1 or even 20:1) and then increase the level of the signal at
the compressor input to the point that even the softest passages are
compressed slightly.

There are a few hardware audio levelers, but they typically range in
price from a thousand dollars upward.  Levelers allow setting of a
"target" level for the output, and increase the gain when the input
level is below the target.  When the input level is above the target, a
leveler acts as a conventional compressor, with user-adjustable
compression ratio.  

So, can I use SND for leveling?  Or is there another package which is
more suitable?

I have not yet attempted to use SND.  I presently am using Audacity for
audio editing in the Debian/Gnome environment.