Echo Removal -Sound Forge - PC - MAGIX Community Forums Archive

Subject:Echo Removal Posted by: scooter Date:6/13/2000 5:35:00 PM I have most of Sonic Foundry's Products, Including SF 4.5, Accoustical mirror 1.1, and the noise reduction 1.0 plugin. I'm looking for some advice on how to use these to remove an echo from some recorded tape. Does anyone have any hints? Thank you, Marc Franklin
Subject:Re: Echo Removal Reply by: mattm Date:6/16/2000 10:57:00 AM Marc, How long is the echo? What kind of content on the tape? Are we talking an actual delay or just a ring? If the former, this can be very difficult to do, and probably impossible to get perfect, especially with continuous content. If your selection isn't very long, you may be able to manually edit it in Sound Forge, try using noise gate, or a combo of these two. If the latter (a ring), try an EQ. Matt Miller Marc wrote: >>I have most of Sonic Foundry's Products, Including SF 4.5, >>Accoustical mirror 1.1, and the noise reduction 1.0 >>plugin. I'm looking for some advice on how to use these to >>remove an echo from some recorded tape. Does anyone have >>any hints? >> >>Thank you, >> >>Marc Franklin
Subject:Re: Echo Removal Reply by: scooter Date:6/20/2000 3:12:00 PM >>Matt >> Its more of the ringing from a large room. its a fairly long piece at around 15 minutes. Do you have any specific settings that you would suggest? Marc
Subject:Re: Echo Removal Reply by: mattm Date:6/21/2000 1:46:00 PM Ok, room reverberation is nearly impossible to remove in most cases. It's a complex beast. I'm assuming your audio is a peice of music, and it's downright impossible to edit out reverb tails without seriously altering the harmonic content of the music. And it would take a lot of work. Having said that, you could quickly play around with the noise gate threshold to try to remove the reverb from silences in the music, but that may or may not give you much of an improvement. My best advice is to try to live with it ;) Matt Marc wrote: >> >> >>>>Matt >>>> >>Its more of the ringing from a large room. its a fairly long piece >>at around 15 minutes. Do you have any specific settings that you >>would suggest? >> >>Marc
Subject:RE: Re: Echo Removal Reply by: michael_ellenby Date:3/25/2001 12:39:47 PM I have a similar problem - I have a a 60 minute speech done in an echoey room. The audience is silent (you wouldn't know they were there!) but there is a conistent echo. I want to make this a commercial speech on tape product and I want to remove the echo - any ideas?
Subject:RE: Re: Echo Removal Reply by: nlamartina Date:3/25/2001 1:40:47 PM To those who wish to remove an echo: THIS IS VERY DIFFICULT TO DO, BUT POSSIBLE (sorta)! That being said, keep in mind that you will NEVER get the audio to sound like the original after you mess with it. Removing/reducing echo tends to make the sound very hallow and tin-can-sounding. But at least you can try to see if you're happy with the results. We need to first discuss what exactly composes reverb, so you may better know your enemy. Reverb is not simply a carbon copy repeat of your sound, but rather a molding and mutation of your sound, mixed with the original at a delayed interval that will either breath life or administer death to your recordings. Here are the BASIC components that make up reverb: Decay time- the amount of time it takes for the echo to drop below 60dB after the initial sound (basically how long the echo is). Early reflections- gives the listener a sense of confined space, i.e., the presence of close walls. Perfectly appropriate for public speaking or corporate presentations, but sometimes disorienting to singers. High/Low frequency absorption- the walls in a venue either reflect or absorb frequencies (actually, both are done, since a wave loses energy each time it bounces). Some frequencies will bounce very easily, while others will be almost completely absorbed. Now, there are lots of other parameters present in reverb, but keep these in mind because they’ll be the ones we’ll try to counter. Please do the following to gather a bit of data: 1. Open your sound file. 2. Go to the TOOLS menu and select SPECTRUM ANALYSIS. 3. In this window, go to the DISPLAY menu and select LOGIRITHMIC. 4. Make sure you also select ZOOM OUT FULL and FILLED GRAPH. What you are looking at now is a graphical representation of what is happening in your file. The black line that traces the mountains and valleys of this graph is your noise print. What we need to do to help reduce the echo is remove all the audio information from just above that line, i.e., cleave the top of your graph off to make it smooth, reducing all noise above that reference. So how do we do this? NOT EASY! If you have DC Audio Restoration tools, just take a noise print and hit OK, but with Sound Forge the process is a little more difficult. First, take note of the coordinates of your noise print. Make a quick mental picture, and minimize this window. Now do the following: 1. Go to the DIRECTX menu and select SONIC FOUNDRY TRACK EQ (if you don’t have this feature, we might as well stop here). 2. Arrange each of the four cutoffs (the blue thingies) to create an upside-down image of the mountain you took a mental picture of earlier. This takes a lot of practice. What you’re trying to do is remove the echo coloration by reversing the “EQ effect” reverb has on the sound. Think of it this way… When the sound bounces around the venue, some frequencies get amplified (reflection), and some frequencies get reduced (absorption). You need to reverse that. Keep in mind it’s impossible to get rid of near reflections. The best you can do to the recording is make the room sound somewhat smaller. Oh, possibly run a noise gate afterward to remove any echo tails. That’s about all I can tell you. It’s not easy, and the final product usually isn’t very pretty, but hey, it’s worth a try, right? Best thing you can ever do it get it right the first time, but that’s not always possible, and if these are desperate times, then here’s your desperate measure. I hope this helps out, even if a little bit. Best wishes, and good luck, Nick LaMartina

Subject:Echo Removal

Posted by: scooter

Date:6/13/2000 5:35:00 PM

I have most of Sonic Foundry's Products, Including SF 4.5,
Accoustical mirror 1.1, and the noise reduction 1.0
plugin. I'm looking for some advice on how to use these to
remove an echo from some recorded tape. Does anyone have
any hints?

Thank you,

Marc Franklin

Subject:Re: Echo Removal

Reply by: mattm

Date:6/16/2000 10:57:00 AM

Marc,

How long is the echo? What kind of content on the tape?

Are we talking an actual delay or just a ring? If the former, this
can be very difficult to do, and probably impossible to get perfect,
especially with continuous content. If your selection isn't very
long, you may be able to manually edit it in Sound Forge, try using
noise gate, or a combo of these two.

If the latter (a ring), try an EQ.

Matt Miller

Marc wrote:
>>I have most of Sonic Foundry's Products, Including SF 4.5,
>>Accoustical mirror 1.1, and the noise reduction 1.0
>>plugin. I'm looking for some advice on how to use these to
>>remove an echo from some recorded tape. Does anyone have
>>any hints?
>>
>>Thank you,
>>
>>Marc Franklin

Subject:Re: Echo Removal

Reply by: scooter

Date:6/20/2000 3:12:00 PM

>>Matt
>>
Its more of the ringing from a large room. its a fairly long piece
at around 15 minutes. Do you have any specific settings that you
would suggest?

Marc

Subject:Re: Echo Removal

Reply by: mattm

Date:6/21/2000 1:46:00 PM

Ok, room reverberation is nearly impossible to remove in most cases.
It's a complex beast. I'm assuming your audio is a peice of music,
and it's downright impossible to edit out reverb tails without
seriously altering the harmonic content of the music. And it would
take a lot of work.

Having said that, you could quickly play around with the noise gate
threshold to try to remove the reverb from silences in the music, but
that may or may not give you much of an improvement.

My best advice is to try to live with it ;)

Matt

Marc wrote:
>>
>>
>>>>Matt
>>>>
>>Its more of the ringing from a large room. its a fairly long piece
>>at around 15 minutes. Do you have any specific settings that you
>>would suggest?
>>
>>Marc

Subject:RE: Re: Echo Removal

Reply by: michael_ellenby

Date:3/25/2001 12:39:47 PM

I have a similar problem - I have a a 60 minute speech done in an echoey room. The audience is silent (you
wouldn't know they were there!) but there is a conistent echo. I want to make this a commercial speech on tape
product and I want to remove the echo - any ideas?

Subject:RE: Re: Echo Removal

Reply by: nlamartina

Date:3/25/2001 1:40:47 PM

To those who wish to remove an echo:
THIS IS VERY DIFFICULT TO DO, BUT POSSIBLE (sorta)!

That being said, keep in mind that you will NEVER get the
audio to sound like the original after you mess with it.
Removing/reducing echo tends to make the sound very hallow
and tin-can-sounding. But at least you can try to see if
you're happy with the results.

We need to first discuss what exactly composes reverb, so
you may better know your enemy. Reverb is not simply a
carbon copy repeat of your sound, but rather a molding and
mutation of your sound, mixed with the original at a
delayed interval that will either breath life or administer
death to your recordings. Here are the BASIC components
that make up reverb:

Decay time- the amount of time it takes for the echo to
drop below 60dB after the initial sound (basically how long
the echo is).

Early reflections- gives the listener a sense of confined
space, i.e., the presence of close walls. Perfectly
appropriate for public speaking or corporate presentations,
but sometimes disorienting to singers.

High/Low frequency absorption- the walls in a venue either
reflect or absorb frequencies (actually, both are done,
since a wave loses energy each time it bounces). Some
frequencies will bounce very easily, while others will be
almost completely absorbed.

Now, there are lots of other parameters present in reverb,
but keep these in mind because they’ll be the ones we’ll
try to counter. Please do the following to gather a bit of
data:

1. Open your sound file.
2. Go to the TOOLS menu and select SPECTRUM ANALYSIS.
3. In this window, go to the DISPLAY menu and select
LOGIRITHMIC.
4. Make sure you also select ZOOM OUT FULL and FILLED GRAPH.

What you are looking at now is a graphical representation
of what is happening in your file. The black line that
traces the mountains and valleys of this graph is your
noise print. What we need to do to help reduce the echo is
remove all the audio information from just above that line,
i.e., cleave the top of your graph off to make it smooth,
reducing all noise above that reference.

So how do we do this? NOT EASY! If you have DC Audio
Restoration tools, just take a noise print and hit OK, but
with Sound Forge the process is a little more difficult.
First, take note of the coordinates of your noise print.
Make a quick mental picture, and minimize this window. Now
do the following:

1. Go to the DIRECTX menu and select SONIC FOUNDRY TRACK EQ
(if you don’t have this feature, we might as well stop
here).
2. Arrange each of the four cutoffs (the blue thingies) to
create an upside-down image of the mountain you took a
mental picture of earlier. This takes a lot of practice.

What you’re trying to do is remove the echo coloration by
reversing the “EQ effect” reverb has on the sound. Think of
it this way… When the sound bounces around the venue, some
frequencies get amplified (reflection), and some
frequencies get reduced (absorption). You need to reverse
that. Keep in mind it’s impossible to get rid of near
reflections. The best you can do to the recording is make
the room sound somewhat smaller. Oh, possibly run a noise
gate afterward to remove any echo tails.

That’s about all I can tell you. It’s not easy, and the
final product usually isn’t very pretty, but hey, it’s
worth a try, right? Best thing you can ever do it get it
right the first time, but that’s not always possible, and
if these are desperate times, then here’s your desperate
measure. I hope this helps out, even if a little bit.

Best wishes, and good luck,
Nick LaMartina