In message , Paul
writes:
Bill in Co wrote:
A puzzling audio problem on one of my laptops: I noticed the windows sound
events all sounded lower in pitch than normal (guessing about 3% or
4% lower)

If that _is_ the difference, you have good ears: adjacent semitones (on
an even-tempered scale, which is what's mostly used nowadays) differ by
2^(1/2), which is about 6%, so you're noticing well under that. I think
I would certainly notice that in successive playings, but for a sound
that I only hear for certain events, I don't think I would. (Out of
curiosity, which sounds did you notice this on? What sound scheme are
you using, or is it one you've created yourself?)

on this Dell e6500 laptop. So I copied some of the sound events over
to a temp
folder, and played them using various wav players, and sure enough, they
all sound lower in pitch (with the exception of one wav player, which
renders
the pitch correctly). I think I have finally noticed one thing unique about
this: these windows event sounds are mostly 22.05 kHz, 16 bit wave
files, not the
standard 44.1 kHz. Sitll, they should all play with the correct pitch!

My first thought _was_ a faulty reference crystal, but if it's only
sounds at a certain rate (and only some - even if all but one -
players), then it's not going to be that.

You say you "noticed" it. Do you mean/think it has _started_ doing it,
or has always done it on that machine? (Did you notice it because you
happened to have the same event - and sound - on two machines at around
the same time? There, I too would have noticed half a semitone
difference, I think. [Depending on what the sound was.])

I'd be tempted to load them into something that can do it (Audacity?,
GoldWave), and upsample them to 44100, and see if they then play
correctly - and, try downsampling some 44100 files to 22050, and see if
they then play oddly. (I'm just wondering if there's some other property
that's particular to the sound event files provided by Microsoft. If you
temporarily associate a 44100 Hz .wav file to one of your events, does
it play right?) Though you say it's players too, so not just the Events
subsystem.
[]
See if the ratio is 44100/48000 , implying some driver
is using the wrong sampling rate for something. Audacity has
an FFT display, which can show the frequency of spikes
in the frequency domain graph.

That'd be nearly 9%, or 1½ semitones. (Though Bill did say he _guessed_
at the 3 or 4 %.) Good thinking though.
[]
If it was a crystal timebase reference problem, that's
probably good to 100ppm. And I don't know if human pitch
sensing can detect that small of a shift.

I think the cheapest might be as much as 500 ppm. But that's basic
accuracy, or drift over time (months or years, or with _considerable_
change in temperature). And even that's 0.05%. But - unless the sound
system uses different crystals for different rates, and I can't see it
doing that (certainly not for 22050 and 44100 as they're related) - and
Bill says it's only some playings that are low/slow, I don't think it's
that.

(Writing "low/slow" there made me think: it'd be interesting to see if
it is only pitch, or duration that's affected - but you'd need a longish
[say well over a minute] file, and one with a clearly audible start and
stop [maybe your burst of concert A], to check that. But I suspect
duration _would_ be affected.)

https://en.wikipedia.org/wiki/Pitch_(music)

"Below 500 Hz, the jnd is about 3 Hz for sine waves,
and 1 Hz for complex tones; above 1000 Hz, the jnd for
sine waves is about 0.6% (about 10 cents)."

Which suggests you cannot hear 100ppm of error.

Interesting that it _isn't_ a percentage for low notes (assuming the
above is correct).
[]
--
J. P. Gilliver. UMRA: 1960/1985 MB++G()AL-IS-Ch++(p)Ar@T+H+Sh0!:`)DNAf

"I'm a paranoid agnostic. I doubt the existence of God, but I'm sure there is
some force, somewhere, working against me." - Marc Maron