Quantcast

Removing Reverberation

classic Classic list List threaded Threaded
6 messages Options
Reply | Threaded
Open this post in threaded view
|  
Report Content as Inappropriate

Removing Reverberation

Dave Hartman-2
I have some audio recordings that contain a lot of reverberation, making
the speaker hard to understand.  I've seen that there are filters to add
reverb, but I don't know of any to remove it.  Any suggestions?
(V1.3beta on XP SP3)
Dave

------------------------------------------------------------------------------
This SF.net email is sponsored by Sprint
What will you do first with EVO, the first 4G phone?
Visit sprint.com/first -- http://p.sf.net/sfu/sprint-com-first
************ ASKING FOR HELP ************

When asking for help on this list, please include the following information, so we can
help you properly:

* What operating system you are using (for example, Windows XP or Mac OS X 10.5.1)  

* Exactly what version number of Audacity you are using (Help > About Audacity, or
   Audacity >  About Audacity on a Mac computer)  

* If this is a recording problem, what equipment you are recording with, and how is it
   connected to the computer?

Mailing list: [hidden email]
To UNSUBSCRIBE, use the form at the bottom of this web page:
https://lists.sourceforge.net/lists/listinfo/audacity-users
Reply | Threaded
Open this post in threaded view
|  
Report Content as Inappropriate

Re: Removing Reverberation

Gale (Audacity Team)
Administrator

On Wed, 14 Jul 2010 13:01:41 -0400
Dave Hartman <[hidden email]> wrote:
> I have some audio recordings that contain a lot of reverberation, making
> the speaker hard to understand.  I've seen that there are filters to add
> reverb, but I don't know of any to remove it.  Any suggestions?
> (V1.3beta on XP SP3)

I only know of deverb in Monty's Postfish, which means building it on
Linux:

Download:  http://svn.xiph.org/trunk/postfish/
More details: http://tinyurl.com/39smyob

Sometimes just mixing a stereo reverbed track to mono can make the
reverb less distracting:
http://wiki.audacityteam.org/wiki/Mixing_stereo_tracks_to_mono_in_your_Project



Gale

 






------------------------------------------------------------------------------
This SF.net email is sponsored by Sprint
What will you do first with EVO, the first 4G phone?
Visit sprint.com/first -- http://p.sf.net/sfu/sprint-com-first
************ ASKING FOR HELP ************

When asking for help on this list, please include the following information, so we can
help you properly:

* What operating system you are using (for example, Windows XP or Mac OS X 10.5.1)  

* Exactly what version number of Audacity you are using (Help > About Audacity, or
   Audacity >  About Audacity on a Mac computer)  

* If this is a recording problem, what equipment you are recording with, and how is it
   connected to the computer?

Mailing list: [hidden email]
To UNSUBSCRIBE, use the form at the bottom of this web page:
https://lists.sourceforge.net/lists/listinfo/audacity-users
Reply | Threaded
Open this post in threaded view
|  
Report Content as Inappropriate

Re: Removing Reverberation

Gary Nelson
Reverberation that is long enough duration to make speech difficult to understand will have an impulse response a few (>2 sec) seconds long. The inverse filter needed to remove that reverberation would thus be a few seconds duration -- several 10s of thousands of samples at CD sample rate of 44,100 samples/sec.  In principle, it can be done, but compute times will be substantial.

Estimating the room response from only the recording would be a substantial achievement in itself requiring processing of long duration samples.  As I recall, Apple's Logic Pro offers attempts at teasing out a room's impulse response from recorded samples.  I can't offer any testimonials as I have not tried it.  

BTW, Audacity works very well as a tool to measure reverberation time of a room. Place a microphone, start recording, pop a large balloon**, stop recording, look at results in "waveform in dB" mode with user interface set to 60 dB. The recording of the pop in dB will look like an arrowhead. Normalize to 0dB. Then, when the signal disappears, the time from start of pop response is RT60 or Reverberation TIme to 60dB attenuation.  A room with good speech intelligibility will have RT60 about 1 second. If RT60 is >2 sec, speech intelligibility will suffer. So your room(s) must have RT60 > 2-3 sec -- maybe 100,000 samples or more.  That balloon pop recording is approximately the room's impulse response from the perspective of the microphone (it is different for every microphone location). The point is that removing a long reverberation has to take lots of computation -- could be a few hours. So who's in a hurry?

Gary Nelson

** Another option is to play a short (eg, 1 sec) burst of pink noise as loud as speakers and amp will accomodate without distortion and record while playing that sound.

On Jul 14, 2010, at 6:59 PM, [hidden email] wrote:

>
> On Wed, 14 Jul 2010 13:01:41 -0400
> Dave Hartman <[hidden email]> wrote:
>> I have some audio recordings that contain a lot of reverberation, making
>> the speaker hard to understand.  I've seen that there are filters to add
>> reverb, but I don't know of any to remove it.  Any suggestions?
>> (V1.3beta on XP SP3)
>
> I only know of deverb in Monty's Postfish, which means building it on
> Linux:
>
> Download:  http://svn.xiph.org/trunk/postfish/
> More details: http://tinyurl.com/39smyob
>
> Sometimes just mixing a stereo reverbed track to mono can make the
> reverb less distracting:
> http://wiki.audacityteam.org/wiki/Mixing_stereo_tracks_to_mono_in_your_Project
>
>
>
> Gale
>
>
>
>
>
>
>
>
> ------------------------------------------------------------------------------
> This SF.net email is sponsored by Sprint
> What will you do first with EVO, the first 4G phone?
> Visit sprint.com/first -- http://p.sf.net/sfu/sprint-com-first
> ************ ASKING FOR HELP ************
>
> When asking for help on this list, please include the following information, so we can
> help you properly:
>
> * What operating system you are using (for example, Windows XP or Mac OS X 10.5.1)  
>
> * Exactly what version number of Audacity you are using (Help > About Audacity, or
>  Audacity >  About Audacity on a Mac computer)  
>
> * If this is a recording problem, what equipment you are recording with, and how is it
>  connected to the computer?
>
> Mailing list: [hidden email]
> To UNSUBSCRIBE, use the form at the bottom of this web page:
> https://lists.sourceforge.net/lists/listinfo/audacity-users
>

Gary Nelson
[hidden email]




------------------------------------------------------------------------------
This SF.net email is sponsored by Sprint
What will you do first with EVO, the first 4G phone?
Visit sprint.com/first -- http://p.sf.net/sfu/sprint-com-first
************ ASKING FOR HELP ************

When asking for help on this list, please include the following information, so we can
help you properly:

* What operating system you are using (for example, Windows XP or Mac OS X 10.5.1)  

* Exactly what version number of Audacity you are using (Help > About Audacity, or
   Audacity >  About Audacity on a Mac computer)  

* If this is a recording problem, what equipment you are recording with, and how is it
   connected to the computer?

Mailing list: [hidden email]
To UNSUBSCRIBE, use the form at the bottom of this web page:
https://lists.sourceforge.net/lists/listinfo/audacity-users
Reply | Threaded
Open this post in threaded view
|  
Report Content as Inappropriate

Re: Removing Reverberation

Dave Hartman-2
In reply to this post by Dave Hartman-2
Thanks!
I hadn't heard of Monty's Postfish before.  I'll look into it.
I do have a couple of surplus computers, so I could dedicate one for
this project.
On another note, what's the difference between removing reverberation
(deverberation), and echo cancelling?  Just the time involved?
Dave

------------------------------------------------------------------------------
This SF.net email is sponsored by Sprint
What will you do first with EVO, the first 4G phone?
Visit sprint.com/first -- http://p.sf.net/sfu/sprint-com-first
************ ASKING FOR HELP ************

When asking for help on this list, please include the following information, so we can
help you properly:

* What operating system you are using (for example, Windows XP or Mac OS X 10.5.1)  

* Exactly what version number of Audacity you are using (Help > About Audacity, or
   Audacity >  About Audacity on a Mac computer)  

* If this is a recording problem, what equipment you are recording with, and how is it
   connected to the computer?

Mailing list: [hidden email]
To UNSUBSCRIBE, use the form at the bottom of this web page:
https://lists.sourceforge.net/lists/listinfo/audacity-users
Reply | Threaded
Open this post in threaded view
|  
Report Content as Inappropriate

Re: Removing Reverberation

Dave-211
Hi
Have a look at this program it may help http://www.trueaudio.com/index.htm.
    THANKYOU DAVE-211

----- Original Message -----
From: "Dave Hartman" <[hidden email]>
To: <[hidden email]>
Sent: Sunday, July 18, 2010 9:05 AM
Subject: Re: [Audacity-users] Removing Reverberation


> Thanks!
> I hadn't heard of Monty's Postfish before.  I'll look into it.
> I do have a couple of surplus computers, so I could dedicate one for
> this project.
> On another note, what's the difference between removing reverberation
> (deverberation), and echo cancelling?  Just the time involved?
> Dave
>
> ------------------------------------------------------------------------------
> This SF.net email is sponsored by Sprint
> What will you do first with EVO, the first 4G phone?
> Visit sprint.com/first -- http://p.sf.net/sfu/sprint-com-first
> ************ ASKING FOR HELP ************
>
> When asking for help on this list, please include the following
> information, so we can
> help you properly:
>
> * What operating system you are using (for example, Windows XP or Mac OS X
> 10.5.1)
>
> * Exactly what version number of Audacity you are using (Help > About
> Audacity, or
>   Audacity >  About Audacity on a Mac computer)
>
> * If this is a recording problem, what equipment you are recording with,
> and how is it
>   connected to the computer?
>
> Mailing list: [hidden email]
> To UNSUBSCRIBE, use the form at the bottom of this web page:
> https://lists.sourceforge.net/lists/listinfo/audacity-users
>


------------------------------------------------------------------------------
This SF.net email is sponsored by Sprint
What will you do first with EVO, the first 4G phone?
Visit sprint.com/first -- http://p.sf.net/sfu/sprint-com-first
************ ASKING FOR HELP ************

When asking for help on this list, please include the following information, so we can
help you properly:

* What operating system you are using (for example, Windows XP or Mac OS X 10.5.1)  

* Exactly what version number of Audacity you are using (Help > About Audacity, or
   Audacity >  About Audacity on a Mac computer)  

* If this is a recording problem, what equipment you are recording with, and how is it
   connected to the computer?

Mailing list: [hidden email]
To UNSUBSCRIBE, use the form at the bottom of this web page:
https://lists.sourceforge.net/lists/listinfo/audacity-users
Reply | Threaded
Open this post in threaded view
|  
Report Content as Inappropriate

Re: Removing Reverberation

Gale (Audacity Team)
Administrator

"Dave" <[hidden email]> wrote on
Sun, 18 Jul 2010 23:26:37 +1000:
> Have a look at this program it may help http://www.trueaudio.com/index.htm.

Did you mean to scroll down and look at this link:
http://www.trueaudio.com/at_echo.htm  ?

Dave Hartman wrote on  Sunday, July 18, 2010 9:05 AM
>> On another note, what's the difference between removing reverberation
>> (deverberation), and echo cancelling?  Just the time involved?

I tend to think of "echo cancellation" as a specific application to
telecommunications:
http://en.wikipedia.org/wiki/Echo_cancellation 

where it's as often done by hardware as software, and the reverb
you're dealing with is a good deal more predictable.

This is an interesting thread too (well, until half way down):
http://forum.cakewalk.com/tm.aspx?m=173996




Gale




------------------------------------------------------------------------------
This SF.net email is sponsored by Sprint
What will you do first with EVO, the first 4G phone?
Visit sprint.com/first -- http://p.sf.net/sfu/sprint-com-first
************ ASKING FOR HELP ************

When asking for help on this list, please include the following information, so we can
help you properly:

* What operating system you are using (for example, Windows XP or Mac OS X 10.5.1)  

* Exactly what version number of Audacity you are using (Help > About Audacity, or
   Audacity >  About Audacity on a Mac computer)  

* If this is a recording problem, what equipment you are recording with, and how is it
   connected to the computer?

Mailing list: [hidden email]
To UNSUBSCRIBE, use the form at the bottom of this web page:
https://lists.sourceforge.net/lists/listinfo/audacity-users
Loading...