You know that annoying sound that a Nextel cell phone makes if it is
too close to your car stereo or computer speakers? I need to remove
that noise from a recording! It's a tough task, here's what I've
tried so far:
1) Spectrum analysis of the noise shows it is all over the audio
band, so eq is not helpful.
2) I copied an individual instance of the sound, inverted the phase,
and mixed it with the original. This of course worked, but each
"click" is unique, and the rate changes slightly over time.

Here's what it sounds like:
http://www.steelinfromdan.com/sounds/CD.mp3

Any help is greatly appreciated!

In article writes:

2) I copied an individual instance of the sound, inverted the phase,
and mixed it with the original. This of course worked, but each
"click" is unique, and the rate changes slightly over time.

Well, you know what you need to do. Hope you have a lot of time. There
are no inexpensive automatic solutions, and maybe not even any
expensive automatic solutions.



--
I'm really Mike Rivers )
However, until the spam goes away or Hell freezes over,
lots of IP addresses are blocked from this system. If
you e-mail me and it bounces, use your secret decoder ring
and reach me he double-m-eleven-double-zero at yahoo

Mike Rivers wrote:

In article writes:


2) I copied an individual instance of the sound, inverted the phase,
and mixed it with the original. This of course worked, but each
"click" is unique, and the rate changes slightly over time.


Well, you know what you need to do. Hope you have a lot of time. There
are no inexpensive automatic solutions, and maybe not even any
expensive automatic solutions.

You could probably load it up in Matlab and write a script to do it.
You can detect the KSSSSSH because it's broadband noise. You can look
at the sound immediately before and after it to tell which frequencies
are legit, and you can filter out everything but that by summing some
narrow bandpass filters (selected using your list of legit frequencies)
during the offending periods.

Not that I am volunteering. But the point is, if you are willing to
spend a day on it, you could probably generate such a filter.

Or you could just do it all manually and probably be done quicker...

- Logan

In article writes:

2) I copied an individual instance of the sound, inverted the phase,
and mixed it with the original. This of course worked, but each
"click" is unique, and the rate changes slightly over time.

Then it's not really a periodic noise, is it?

You're going to have to cut and paste each one of them by hand, and then
work around the residue by cutting other sections of the note (or other
notes) over top of them. It may well be easier to retrack.

Just another reason why good monitoring is so important, even for tracking.
--scott

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

(Scott Dorsey) wrote in message ...
Then it's not really a periodic noise, is it?

Man, helpful bunch here, eh?

How many times does a noise need to repeat in order to be technically
called a periodic noise? I see where you are coming from, but I
wanted to come up with a description that would quickly describe the
sound.


... It may well be easier to retrack.
This was a recording of a one-time event -- sometimes, you cannot
re-record.


Just another reason why good monitoring is so important, even for tracking.

I again see your point, but this was an unattended, automated
recording. My dumb luck that a cell-phone-carrying individual would
happen by and be close enough to the condensor mic!

In article writes:

How many times does a noise need to repeat in order to be technically
called a periodic noise?

42?

Actually, "periodic" noise is something that would repeat forever if
something didn't stop it. Because it's periodic, it's repeatable and
you can apply a processing tool that can recognize it and remove or
reduce it.

Air conditioning fan noise is "periodic." Cars passing three or five
times per minute aren't periodic, but each car might be close enough
to periodic so that you can remove their noise individually. That's
why you have a tough job ahead of you.

I again see your point, but this was an unattended, automated
recording. My dumb luck that a cell-phone-carrying individual would
happen by and be close enough to the condensor mic!

Unattended recordings often have problems like this because audio
(at least audio interesting enough to record) isn't constant. Whether
you could have done anything about it if you were there is another
issue.

--
I'm really Mike Rivers )
However, until the spam goes away or Hell freezes over,
lots of IP addresses are blocked from this system. If
you e-mail me and it bounces, use your secret decoder ring
and reach me he double-m-eleven-double-zero at yahoo