tomr@ashtate (Tom Rombouts) (05/26/90)
In article <1990May23.162547.26538@agate.berkeley.edu> wainscot@math.berkeley.edu (Brian Wainscott) writes: >Is is possible, and if so how, to control the VOLUME of the speaker >on my PC. I'm working on some music composition programs, and don't >want to disturb my whole family while tinkering at 1 am. > I was involved in this question about three months ago and recieved a definitive "no" answer, although there are TSR's that attempt to shut off the speaker entirely. (In my experience, I found that certain apps seemed to turn it back on. In some other apps it was muted, but still slightly audible.) Please correct me if I am wrong - I ended up opening the box and physically cutting the wires! Tom Rombouts, Ashton-Tate, Voice: (213) 538-7108
mpe@shamash.cdc.com (2375) (05/28/90)
You can seemingly control the speaker volume by alternating the interval
between tones. An example of a routine is:
for i:=1 to count do
begin
sound(1000);
nosound;
delay(volume);
end;
In this routine, the tone of the sound is the value 1000 and the volume
is somewhat controlled by the delay interval between sounds. Please note,
the method outlined here only approximates the function you want and the
REAL output tone will be a rather complex combination of the actual sound
tone and the delay time. Find someone who knows something about FFT's
to explain what I mean...
As for a TSR routine to implement this, I leave that to the reader as
an exercise.
The fastest method that I know to implement a solution to control the
volume of a PC for the purpose of not waking everyone up during midnight
programming sessions is to splice-in a variable resistor is series with
the speaker.
cat *flame* > /dev/null
.KRW1@Lehigh (05/28/90)
Yes, it is possible to control the volume of the PC speaker, but probably not in a way that is suitable for most applications. The techniques used for playing digitized sound allow the reproduction of any audio signal within about a 35 db volume range. Unfortunately, this requires increasing the system timer interrupt rate to 8-16KHz, not giving you time to do much else except service the interrupt on slower machines. On the other hand, if you're not interested much in sound quality, that interrupt rate could probably be lowered. Haven't tried it for simple tones. It might be feasible. -- Kevin