[[email protected]]

A question--

I've been processing some audio from a bunch of different (cheap)
microphones, and after correcting for DC offset, I notice that a
couple of them produce waveforms that are significantly larger on one
side of 0 than the other, by about 50%. (They are that way before the
DC offset too, I'm just saying it's not that.)

My only guess is that the microphone diaphragm moves more easily in
one direction that the other.

Does this negatively impact sound quality to a high degree, subtley,
or not at all? Is there software to automatically correct it, either
boosting the weaker half or diminishing the stronger half (as there is
software to remove DC offset), and would this improve sound quality?

Thanks
Michael

[Don Pearce]

On Thu, 05 Jul 2007 10:37:41 -0700, wrote:

A question--

I've been processing some audio from a bunch of different (cheap)
microphones, and after correcting for DC offset, I notice that a
couple of them produce waveforms that are significantly larger on one
side of 0 than the other, by about 50%. (They are that way before the
DC offset too, I'm just saying it's not that.)

My only guess is that the microphone diaphragm moves more easily in
one direction that the other.

Does this negatively impact sound quality to a high degree, subtley,
or not at all? Is there software to automatically correct it, either
boosting the weaker half or diminishing the stronger half (as there is
software to remove DC offset), and would this improve sound quality?

Thanks
Michael

No problems there - that is just how sounds are.Asymmetrical waveforms
are rich in even harmonics, and there are plenty of those out there.

d

--
Pearce Consulting
http://www.pearce.uk.com

[Paul Stamler]

wrote in message
oups.com...
A question--

I've been processing some audio from a bunch of different (cheap)
microphones, and after correcting for DC offset, I notice that a
couple of them produce waveforms that are significantly larger on one
side of 0 than the other, by about 50%. (They are that way before the
DC offset too, I'm just saying it's not that.)

My only guess is that the microphone diaphragm moves more easily in
one direction that the other.

Does this negatively impact sound quality to a high degree, subtley,
or not at all? Is there software to automatically correct it, either
boosting the weaker half or diminishing the stronger half (as there is
software to remove DC offset), and would this improve sound quality?

Many voices and instruments produce asymmetrical air pressures, and
microphones will usually reproduce the asymmetry pretty accurately.

Peace,
Paul

[[email protected]]

On Jul 5, 2:41 pm, (Don Pearce) wrote:
On Thu, 05 Jul 2007 10:37:41 -0700, wrote:
A question--

I've been processing some audio from a bunch of different (cheap)
microphones, and after correcting for DC offset, I notice that a
couple of them produce waveforms that are significantly larger on one
side of 0 than the other, by about 50%. (They are that way before the
DC offset too, I'm just saying it's not that.)

My only guess is that the microphone diaphragm moves more easily in
one direction that the other.

Does this negatively impact sound quality to a high degree, subtley,
or not at all? Is there software to automatically correct it, either
boosting the weaker half or diminishing the stronger half (as there is
software to remove DC offset), and would this improve sound quality?

Thanks
Michael

No problems there - that is just how sounds are.Asymmetrical waveforms
are rich in even harmonics, and there are plenty of those out there.

d

--
Pearce Consultinghttp://www.pearce.uk.com


Really? So a 1-minute voice recording that seems to be about 50%
"heavier" on the bottom half of the waveform, consistently during the
entire recording, is natural? I'm not looking at the waveforms up
close, I'm talking about looking at a view of a whole minute on my
screen...

[Don Pearce]

On Thu, 05 Jul 2007 10:50:28 -0700, wrote:

On Jul 5, 2:41 pm, (Don Pearce) wrote:
On Thu, 05 Jul 2007 10:37:41 -0700, wrote:
A question--

I've been processing some audio from a bunch of different (cheap)
microphones, and after correcting for DC offset, I notice that a
couple of them produce waveforms that are significantly larger on one
side of 0 than the other, by about 50%. (They are that way before the
DC offset too, I'm just saying it's not that.)

My only guess is that the microphone diaphragm moves more easily in
one direction that the other.

Does this negatively impact sound quality to a high degree, subtley,
or not at all? Is there software to automatically correct it, either
boosting the weaker half or diminishing the stronger half (as there is
software to remove DC offset), and would this improve sound quality?

Thanks
Michael

No problems there - that is just how sounds are.Asymmetrical waveforms
are rich in even harmonics, and there are plenty of those out there.

d

--
Pearce Consultinghttp://www.pearce.uk.com


Really? So a 1-minute voice recording that seems to be about 50%
"heavier" on the bottom half of the waveform, consistently during the
entire recording, is natural? I'm not looking at the waveforms up
close, I'm talking about looking at a view of a whole minute on my
screen...

Yup. Absolutely fine.

d

--
Pearce Consulting
http://www.pearce.uk.com

[Scott Dorsey]

wrote:

I've been processing some audio from a bunch of different (cheap)
microphones, and after correcting for DC offset, I notice that a
couple of them produce waveforms that are significantly larger on one
side of 0 than the other, by about 50%. (They are that way before the
DC offset too, I'm just saying it's not that.)

This is the way music is.

My only guess is that the microphone diaphragm moves more easily in
one direction that the other.

Yes, because the waveform that is hitting the diaphragm is not symmetric.

Does this negatively impact sound quality to a high degree, subtley,
or not at all? Is there software to automatically correct it, either
boosting the weaker half or diminishing the stronger half (as there is
software to remove DC offset), and would this improve sound quality?

No, it's a very good thing.

Of course, you can compress the crap out of everything and it'll be nice
and symmetric, but it won't sound very good.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

[Scott Dorsey]

wrote:

Really? So a 1-minute voice recording that seems to be about 50%
"heavier" on the bottom half of the waveform, consistently during the
entire recording, is natural? I'm not looking at the waveforms up
close, I'm talking about looking at a view of a whole minute on my
screen...

Could well be, depending on the person speaking.

Try it with a figure-8 mike. Flip the mike around and if the waveform
is inverted, it's the speaker.
--scott

--
"C'est un Nagra. C'est suisse, et tres, tres precis."

[Deputy Dumbya Dawg[_6_]]

wrote in message
oups.com...
A question--

I've been processing some audio from a bunch of different
(cheap)
microphones, and after correcting for DC offset, I notice
that a
couple of them produce waveforms that are significantly
larger on one
side of 0 than the other, by about 50%. (They are that way
before the
DC offset too, I'm just saying it's not that.)

My only guess is that the microphone diaphragm moves more
easily in
one direction that the other.

Guess again.

The soundwave may be more powerful one way or the other due to
the source or perhaps the speaker system producing the sound
you are recording. I would worry only if you are recording a
sine wave and this happens.

Try a few mics in the same place and simultaneously compare
them recording the same source.

Peace
dawg

[Richard Crowley]

wrote...
(Don Pearce) wrote:
No problems there - that is just how sounds are.Asymmetrical waveforms
are rich in even harmonics, and there are plenty of those out there.

Really? So a 1-minute voice recording that seems to be about 50%
"heavier" on the bottom half of the waveform, consistently during the
entire recording, is natural? I'm not looking at the waveforms up
close, I'm talking about looking at a view of a whole minute on my
screen...

I can show you 90-120 minute recordings of speech that look
exactly like that. I have been transcribing them from audio cassette
and you can readily tell which are from "Side A" vs. "Side B" just by
whether the positive or negative side of the waveform predominates.

[[email protected]]

OK, thanks a lot!

[H. Schaap]

"Paul Stamler" schreef in bericht
...
Many voices and instruments produce asymmetrical air pressures, and
microphones will usually reproduce the asymmetry pretty accurately.

Yeah, especially vocals and trumpets.

Henk

[Roy W. Rising[_2_]]

wrote:
On Jul 5, 2:41 pm, (Don Pearce) wrote:
On Thu, 05 Jul 2007 10:37:41 -0700, wrote:
A question--

I've been processing some audio from a bunch of different (cheap)
microphones, and after correcting for DC offset, I notice that a
couple of them produce waveforms that are significantly larger on one
side of 0 than the other, by about 50%. (They are that way before the
DC offset too, I'm just saying it's not that.)

My only guess is that the microphone diaphragm moves more easily in
one direction that the other.

Does this negatively impact sound quality to a high degree, subtley,
or not at all? Is there software to automatically correct it, either
boosting the weaker half or diminishing the stronger half (as there is
software to remove DC offset), and would this improve sound quality?

Thanks
Michael

No problems there - that is just how sounds are.Asymmetrical waveforms
are rich in even harmonics, and there are plenty of those out there.

d

--
Pearce Consultinghttp://www.pearce.uk.com

Really? So a 1-minute voice recording that seems to be about 50%
"heavier" on the bottom half of the waveform, consistently during the
entire recording, is natural? I'm not looking at the waveforms up
close, I'm talking about looking at a view of a whole minute on my
screen...

The human voice (and some instruments) has more positive-going energy and
the waveform should be "heavier" on the top half. The recording you
describe is out of phase somewhere. A fully phase coherent system will
output from the speakers the same "more positive" signal as the source.

Listen to a voice recording and flip the phase. You'll learn to hear the
difference, and to choose the right phase for correct reproduction.

--
~ Roy
"If you notice the sound, it's wrong!"

[Scott Dorsey]

Roy W. Rising wrote:
The human voice (and some instruments) has more positive-going energy and
the waveform should be "heavier" on the top half. The recording you
describe is out of phase somewhere. A fully phase coherent system will
output from the speakers the same "more positive" signal as the source.

Not always. Some folks have more negative-going energy in their voice.
When I first worked at an AM radio station, the station used asymmetric
limiting (since you can modulate the signal above rated power but not
below zero power), and one of the jobs of the engineering staff was to
try out new announcers and see if they should speak into the front or the
back of the figure-8 mikes. Most folks used the front, but some folks
used the back.

Listen to a voice recording and flip the phase. You'll learn to hear the
difference, and to choose the right phase for correct reproduction.

Absolutely!
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

[Ty Ford]

On Thu, 5 Jul 2007 13:37:41 -0400, wrote
(in article .com):

A question--

I've been processing some audio from a bunch of different (cheap)
microphones, and after correcting for DC offset, I notice that a
couple of them produce waveforms that are significantly larger on one
side of 0 than the other, by about 50%. (They are that way before the
DC offset too, I'm just saying it's not that.)

My only guess is that the microphone diaphragm moves more easily in
one direction that the other.

Does this negatively impact sound quality to a high degree, subtley,
or not at all? Is there software to automatically correct it, either
boosting the weaker half or diminishing the stronger half (as there is
software to remove DC offset), and would this improve sound quality?

Thanks
Michael


Michael,

Sound is not symetrical.

Regards,

Ty Ford


--Audio Equipment Reviews Audio Production Services
Acting and Voiceover Demos http://www.tyford.com
Guitar player?:http://www.youtube.com/watch?v=4RZJ9MptZmU

[Meindert Sprang]

wrote in message
oups.com...
Really? So a 1-minute voice recording that seems to be about 50%
"heavier" on the bottom half of the waveform, consistently during the
entire recording, is natural? I'm not looking at the waveforms up
close, I'm talking about looking at a view of a whole minute on my
screen...

I think you mistake DC offset for signal asymmetry. If you would consider
the following signal, squared for simplicity:

Positive amplitude of 3V during 1 second, then a negative amplitude of 1V
during 3 seconds.

This signal will appear to have a DC offset when you look at a long stretch
of it, but it has no DC offset at all because both positive and negative
part have the same area (amplitude x time). Many natural sounds (voice,
instruments) have the same kind of signal, which is caused by the harmonics
of the fundamental frequency.

Meindert