At 13:04 16/05/97 -0400, you wrote:
>
>This is the equal loudness problem. Take a look at the 
>Fletcher-Munson equal loudness curves.
>
>Paul Koonce
>
>On Wed, 14 May 1997, Mike Chapman wrote:
>
>> Hi,
>> 
>> When fading out on my mixing desk i think the bass fades quicker
>> than the trebble. Is there an equation / rule for this?
>> 
>> A constant fade filter might be interesting.
>> 
>> Bye.

And don't forget that the F-M curves refer to absolute level relative to
the threshold of hearing, and not arbitrary dB values. A true 'constant
fade' would have to take into account the volume setting and sensitivity of
the amplifier and speakers! 

R.