29 May
2006
29 May
'06
4:05 a.m.
Hi there.
I have an interview with a lot of AC hum. I'd like to remove as much
of the hum as possible. This is not for broadcasting. I just want to
be able to hear what the persons on the recording are saying.
I've looked at the sound in a frequency spectrum analyzer[1]. The hum
looks just as consistent as it sounds so I guess there must be a way
to filter it out. I just don't know which linux tool will do it for
me.
alex
[1] http://www.baudline.com
--
Alex Polite
http://flosspick.org - finding the right open source
29 May
29 May
4:09 a.m.
On Mon, 2006-05-29 at 10:05 +0200, Alex Polite wrote:
Hi there.
I have an interview with a lot of AC hum. I'd like to remove as much
of the hum as possible. This is not for broadcasting. I just want to
be able to hear what the persons on the recording are saying.
I've looked at the sound in a frequency spectrum analyzer[1]. The hum
looks just as consistent as it sounds so I guess there must be a way
to filter it out. I just don't know which linux tool will do it for
me.
Very sharp notch filter?
Gordon.
6:26 a.m.
On 5/29/06, Gordon JC Pearce <wsynth(a)gjcp.net> wrote:
Very sharp notch filter?
Gordon.
Are there any tools that will help me define the notch filter by
looking at the my audio?
alex
--
Alex Polite
http://flosspick.org - finding the right open source
8 a.m.
"Alex Polite" <notmyprivateemail(a)gmail.com> writes:
Are there any tools that will help me define the notch
filter by
looking at the my audio?
Jamin's actually quite good for doing this, since it's got a nice
spectrum display and interactive EQ settings. Failing that, you could
use a LADSPA filter (like "Single band parametric") and a spectrum
analyser (like Jaaa) and just tweak the filter settings until the peak
you see on the analyser disappears.
[player] -> [JACK Rack with SBP] -----+----> [recorder]
|
v
[Jaaa]
If it's really mains hum, then you can probably just cut the
frequencies below 130Hz or so.
--
Adam Sampson <ats(a)offog.org> <http://offog.org/>
8:16 a.m.
Adam Sampson wrote:
"Alex Polite"
<notmyprivateemail(a)gmail.com> writes:
Maybe a notch filter at 60 Hz would be even better ?
Best,
dp
Are there any tools that will help me define the
notch filter by
looking at the my audio?
Jamin's actually quite good for doing this, since it's got a nice
spectrum display and interactive EQ settings. Failing that, you could
use a LADSPA filter (like "Single band parametric") and a spectrum
analyser (like Jaaa) and just tweak the filter settings until the peak
you see on the analyser disappears.
[player] -> [JACK Rack with SBP] -----+----> [recorder]
|
v
[Jaaa]
If it's really mains hum, then you can probably just cut the
frequencies below 130Hz or so.
8:24 a.m.
On Mon, May 29, 2006 at 01:00:07PM +0100, Adam Sampson wrote:
If it's really mains hum, then you can probably just cut the
frequencies below 130Hz or so.
I'm no expert, but if you still hear something after trying
this, you can experiment with extra filters at multiples
of 60Hz, i.e. 180Hz, 240Hz, 300Hz, 360Hz, etc. etc.
With speech you can be rather ruthless. But then to do all of the
harmonics up to 6000Hz, maybe you'd need a programmable
tool. I think you could chop the top off (above 6000Hz) and
no one would be the wiser.
--
Joel Roth
10:13 a.m.
On Mon, 2006-05-29 at 12:26 +0200, Alex Polite wrote:
On 5/29/06, Gordon JC Pearce <wsynth(a)gjcp.net>
wrote:
With JAMin you should be able to see the problem frequencies. If
you want a *really* sharp notch filter just place the pencil cursor at
the bottom of the hand-drawn EQ display and click twice. For something
a little less drastic you can use the parametric controls in the
hand-drawn EQ.
--
Jan 'Evil Twin' Depner
The Fuzzy Dice
http://myweb.cableone.net/eviltwin69/fuzzy.html
"As we enjoy great advantages from the invention of others, we should be
glad of an opportunity to serve others by any invention of ours, and
this we should do freely and generously."
Benjamin Franklin, on declining patents offered by the governor of
Pennsylvania for his "Pennsylvania Fireplace", c. 1744
Very sharp notch filter?
Gordon.
Are there any tools that will help me define the notch filter by
looking at the my audio?
8:17 a.m.
On Mon, 29 May 2006 09:08:58 +0100
Gordon JC Pearce <wsynth(a)gjcp.net> wrote:
On Mon, 2006-05-29 at 10:05 +0200, Alex Polite wrote:
If it's just for speech then you don't need a notch filter at all, just
kill everything below 300Hz. A simple graphic equaliser should be able
to do a reasonable job of this. Giving a small boost at around 4kHz can
also help improve clarity.
--
F
Hi there.
I have an interview with a lot of AC hum. I'd like to remove as much
of the hum as possible. This is not for broadcasting. I just want to
be able to hear what the persons on the recording are saying.
I've looked at the sound in a frequency spectrum analyzer[1]. The hum
looks just as consistent as it sounds so I guess there must be a way
to filter it out. I just don't know which linux tool will do it for
me.
Very sharp notch filter?
Gordon.
1:16 p.m.
New subject: [linux-audio-user] Re: Removing AC hum after the fact.
Thanks for all the input.
I did some experimentation with jamin. Cutting of everything below 300
Hz sure helped alot. But the harmonics went right through the speech
spectrum so canceling them all out pretty much meant canceling the
speech out as well.
I found freqtweak and hooked that up. It did produce a very beautiful
spectrogram but it didn't solve my problem.
I need something smarter. Something that will 1) take a few seconds
of audio when there's no speech (only hum) and treat that as a
baseline. 2) Reduce the frequencies all over by that baseline.
In effect analyzing the tool would look at the hum and create a filter
that matches it exactly. I guess there's a word for that?
alex
--
Alex Polite
http://flosspick.org - finding the right open source
1:26 p.m.
New subject: [linux-audio-user] Re: Removing AC hum after the fact.
Hi,
Not that you want to use it but Waves X-Hum does a really good job
at this. Go look carefully at their screen shot. Possibly you can
model some group of notch filters like they show and do a better job?
http://www.waves.com/content.asp?id=143
Good luck,
Mark
On 5/29/06, Alex Polite <notmyprivateemail(a)gmail.com> wrote:
Thanks for all the input.
I did some experimentation with jamin. Cutting of everything below 300
Hz sure helped alot. But the harmonics went right through the speech
spectrum so canceling them all out pretty much meant canceling the
speech out as well.
I found freqtweak and hooked that up. It did produce a very beautiful
spectrogram but it didn't solve my problem.
I need something smarter. Something that will 1) take a few seconds
of audio when there's no speech (only hum) and treat that as a
baseline. 2) Reduce the frequencies all over by that baseline.
In effect analyzing the tool would look at the hum and create a filter
that matches it exactly. I guess there's a word for that?
alex
--
Alex Polite
http://flosspick.org - finding the right open source
1:28 p.m.
New subject: [linux-audio-user] Re: Removing AC hum after the fact.
In effect analyzing the tool would look at the hum and create a filter
that matches it exactly. I guess there's a word for that?
Yep noise reduction;) In this case Hum/Buzz Removal.
I havent found a good tool for it in Linux yet myself, though you can
give audacity's noise reduction a shot, I tend to have bad luck with it
as it removes to much IMO.
There are VSTs that will do this if that is an option for you, or other
programs as well, though not nessecarily on Linux(Audition on Windows
has a decent noise reduction for example and is less exxpensive than
many VSTs for that purpose)
Seablade
2:22 p.m.
New subject: [linux-audio-user] Re: Removing AC hum after the fact.
On 5/29/06, Thomas Vecchione <seablaede(a)gmail.com> wrote:
Yep noise reduction;) In this case Hum/Buzz Removal.
W
I havent found a good tool for it in Linux yet myself,
though you can
give audacity's noise reduction a shot, I tend to have bad luck with it
as it removes to much IMO.
Thanks. I tried the one in audacity but it didn't do me any good.
alex
--
Alex Polite
http://flosspick.org - finding the right open source
4:28 p.m.
New subject: [linux-audio-user] Re: Removing AC hum after the fact.
Monday 29 May 2006 20:22, Alex Polite:
Thanks. I tried the one in audacity but it didn't
do me any good.
That must be some son-of-a-gun *hum* you got there. Could you post a snippet
somewhere? I'm a hum collector. Yes, really. Thanks in advance.
--
Wolfgang
4:56 p.m.
New subject: [linux-audio-user] Re: Removing AC hum after the fact.
On Mon, 29 May 2006 22:29:19 +0200
Wolfgang Woehl <tito(a)rumford.de> wrote:
Monday 29 May 2006 20:22, Alex Polite:
Actually from what he describes it's not uncommon. My guess is that it
has been picked up electrostatically rather than electromagnetically so
the upper harmonics will be very much stronger, and indeed may be far
stronger than the fundamental. I bet the recording device had an ultra
cheap, high Z pietzo microphone too :(
All of which is no help of course!
--
F
Thanks. I tried the one in audacity but it
didn't do me any good.
That must be some son-of-a-gun *hum* you got there. Could you post a snippet
somewhere? I'm a hum collector. Yes, really. Thanks in advance.
30 May
30 May
3:12 a.m.
New subject: [linux-audio-user] Re: Removing AC hum after the fact.
On 5/29/06, Wolfgang Woehl <tito(a)rumford.de> wrote:
Monday 29 May 2006 20:22, Alex Polite:
The material is kind of confidential but I'll think I now how to
reproduce the exact same hum. I'll do i little recording especially
for your collection later on this week :)
alex
--
Alex Polite
http://flosspick.org - finding the right open source
Thanks. I tried the one in audacity but it
didn't do me any good.
That must be some son-of-a-gun *hum* you got there. Could you post a snippet
somewhere? I'm a hum collector. Yes, really. Thanks in advance.
4:54 a.m.
New subject: [linux-audio-user] Re: Removing AC hum after the fact.
Tuesday 30 May 2006 09:12, Alex Polite:
On 5/29/06, Wolfgang Woehl <tito(a)rumford.de>
wrote:
Cool, thank you. Think I'll ask Ron for some turkey cawlin' too. But then that
might be confidential just as well.
--
Wolfgang
Monday 29 May 2006 20:22, Alex Polite:
The material is kind of confidential but I'll think I now how to
reproduce the exact same hum. I'll do i little recording especially
for your collection later on this week :) Thanks. I tried the one in audacity but it
didn't do me any good.
That must be some son-of-a-gun *hum* you got there. Could you post a
snippet somewhere? I'm a hum collector. Yes, really. Thanks in advance. 
8:24 a.m.
New subject: [linux-audio-user] Re: Removing AC hum after the fact.
--- Wolfgang Woehl <tito(a)rumford.de> wrote:
Tuesday 30 May 2006 09:12, Alex Polite:
Finding it could be problematic. I save everything but
haven't seen this stuff since removing the noise about
a year ago. I must have it. I'll look later today.
I could ask for copies of the penile and vaginal
surgery feeds I did this month. Mmmm, audio and video
noise. If anyone is erectilely challanged, let me
know. I've watched enough video to feel confidant
performing the corectional surgery at a cut rate--my
investment is a pocket knife and a flashlight. My
flashlite kicks butt. It's an Inova rechargable but
that's another topic.
ron
On 5/29/06, Wolfgang Woehl
<tito(a)rumford.de>
wrote:
> Monday 29 May 2006 20:22, Alex Polite:
> > Thanks. I tried the one in audacity but it
didn't do me any good.
>
> That must be some son-of-a-gun *hum* you got
there. Could you post a
> snippet somewhere? I'm a hum collector.
Yes,
really. Thanks in advance.
The material is kind of confidential but I'll
think I now how to
reproduce the exact same hum. I'll do i
little
recording especially
for your collection later on this week :)
Cool, thank you. Think I'll ask Ron for some turkey
cawlin' too. But then that
might be confidential just as well. Wolfgang
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29 May
29 May
1:45 p.m.
New subject: [linux-audio-user] Re: Removing AC hum after the fact.
On Mon, 2006-05-29 at 19:16 +0200, Alex Polite wrote:
Thanks for all the input.
I did some experimentation with jamin. Cutting of everything below 300
Hz sure helped alot. But the harmonics went right through the speech
spectrum so canceling them all out pretty much meant canceling the
speech out as well.
I found freqtweak and hooked that up. It did produce a very beautiful
spectrogram but it didn't solve my problem.
I need something smarter. Something that will 1) take a few seconds
of audio when there's no speech (only hum) and treat that as a
baseline. 2) Reduce the frequencies all over by that baseline.
Take a look at Gnome Wave Cleaner. You can select a section and use
it as a noise signature. It works pretty good for vinyl.
--
Jan 'Evil Twin' Depner
The Fuzzy Dice
http://myweb.cableone.net/eviltwin69/fuzzy.html
"As we enjoy great advantages from the invention of others, we should be
glad of an opportunity to serve others by any invention of ours, and
this we should do freely and generously."
Benjamin Franklin, on declining patents offered by the governor of
Pennsylvania for his "Pennsylvania Fireplace", c. 1744
2:23 p.m.
New subject: [linux-audio-user] Re: Removing AC hum after the fact.
On Monday 29 May 2006 11:16, Alex Polite wrote:
Thanks for all the input.
I did some experimentation with jamin. Cutting of everything below 300
Hz sure helped alot. But the harmonics went right through the speech
spectrum so canceling them all out pretty much meant canceling the
speech out as well.
I found freqtweak and hooked that up. It did produce a very beautiful
spectrogram but it didn't solve my problem.
I need something smarter. Something that will 1) take a few seconds
of audio when there's no speech (only hum) and treat that as a
baseline. 2) Reduce the frequencies all over by that baseline.
In effect analyzing the tool would look at the hum and create a filter
that matches it exactly. I guess there's a word for that?
Yes, I think it's gnomewavecleaner (http://gwc.sourceforge.net/).
Seriously, though, it sounds like you want a
de-hiss/hum/noise/snap/crackle/pop (okay maybe not so serious) utility which
would take a lot of the manual labour out of it. I don't think there's any
magic solution, but maybe GWC would help. There's others as well (e.g.
http://home.snafu.de/wahlm/dl8hbs/declick.html -- kind of old and sketchy but
easy to use).
HTH,
Curtis S.
5:51 p.m.
New subject: [linux-audio-user] Re: Removing AC hum after the fact.
garbage in, garbage out; sometimes it's a hard learned
lesson. if cutting 300hz and below is causing the loss
of hum and speech then it must be a real bad
recording. i've used the Rezound arbitrary fir filter
to remove air conditioner fans from the U.S. national
turkey and owl callers conferance. of course filtering
is filtering and...
ron
--- Alex Polite <notmyprivateemail(a)gmail.com> wrote:
Thanks for all the input.
I did some experimentation with jamin. Cutting of
everything below 300
Hz sure helped alot. But the harmonics went right
through the speech
spectrum so canceling them all out pretty much meant
canceling the
speech out as well.
I found freqtweak and hooked that up. It did
produce a very beautiful
spectrogram but it didn't solve my problem.
I need something smarter. Something that will 1)
take a few seconds
of audio when there's no speech (only hum) and treat
that as a
baseline. 2) Reduce the frequencies all over by that
baseline.
In effect analyzing the tool would look at the hum
and create a filter
that matches it exactly. I guess there's a word for
that?
alex
--
Alex Polite
http://flosspick.org - finding the right open source
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20 comments
13 participants
participants (13)
-
Adam Sampson -
Alex Polite -
Curtis Sloan -
Dave Phillips -
Folderol -
Gordon JC Pearce -
Jan Depner -
Joel Roth -
Loki Davison -
Mark Knecht -
R Parker -
Thomas Vecchione -
Wolfgang Woehl