I think the wide range of our suggestions, is intended to suggest there
are many sources for sounds in a PC. And you have to be careful not
to get fooled by the source of the sound.
The PC can have a "beeper" used by the BIOS post. In terms of drivers,
a device like that can have a dedicated "square wave" source, so the
BIOS can even make a "European Police car" sound, by reprogramming the
square wave generator once a second and setting a different frequency.
The "beeper" is less likely to make "nuanced" sounds, because the
thing driving it is not designed for normal audio.
The computer audio speakers would be separate devices, perhaps a pair
of stereo speakers, driven by HDaudio subsystem. The "Critical Stop" or
other system sounds would come from that. The BIOS does not tend to drive
the stereo speakers, so is less likely to be sending sounds through
those speakers. The BIOS likes the "beeper", if an alert is needed
at the BIOS level. (The beeper is likely at a known location in the address
map, and the code routine to run it is tiny.) Normal error beeps in the BIOS, would
be at a fixed frequency. And the pattern of beeps indicates an error. The
beep pattern is repeated at regular intervals (so if the machine was
unattended and you come back, you can tell its a BIOS beep pattern).
The hard drive makes a few different sounds, because the motor controller
has more than one option. The motor is multi-phase. If the processor
on the disk drive controller thinks the motor is "stuck", it is possible
to modulate the motor windings in a way intended to "shake the spindle loose".
The idea is, the motor is not powerful enough to overcome even a slight
source of friction. And tearing the heads off the arm is not considered
a good solution either. So modulating the motor, can cause the motor
to make a sound which you might mistake for the system speakers or beeper.
And that is why you have to be careful, when doing acoustic debugging,
not to jump to the wrong conclusion.
On a desktop, even the power supply can make noises, such as
Some computer mechanical noises, are only present for the first
30 seconds, or until something warms up, or in the case of a fan,
it starts spinning on axis again. I have had fans here that would
spin straight. Eventually, they speed up once they spin along
the correct axis, and there is no more "grumble" until the next