Audacity Forum

Hi, I am a new user and am feeling pretty overwhelmed. I am a court reporter and have received some poor-quality audio, but with tips from a friend, figured out how to use noise removal, which was miraculous, however, now the speaker voices are too low for me to hear. When I amplify, it puts some of the distorted noise back in and I am back to square one, unable to clearly make out what the speakers are saying. Is there anything I can do? I tried normalize, also, and it put the distortion and interference back in, too. My problem might be the values I am using? Please keep in mind I am super new, and although I have read many forums and watched some tutorials, I am still in way over my head, so instruct me like a toddler!

Re: noise removal ...
http://forum.audacityteam.org/viewtopic ... 16#p115716

http://forum.audacityteam.org/viewtopic ... 76#p106276

Below is the equalization "curve" for a 300Hz -3000Hz band pass filter ...



You could try something a bit wider first, e.g. 200Hz - 5000Hz

Thanks, Trebor. I did the equalization to close to the example you had. I tried it both before and after noise removal and alone. It does increase the volume on its own, but once noise removal is added in, the volume is taken away. SO frustrating. I have potential money to be earned just sitting here I can't do because I can't figure out how to fix the audio, if it can be fixed.

I'm a bit surprised one of the regulars here hasn't asked it yet - so I will: How exactly are you doing the noise removal? If the volume goes way down when you do the noise removal, then it sounds to me as if the noise sample includes some of the program that you want to keep. For noise removal to work best you need to sample a little bit of your audio that has noise only, make sure none of the voice that you want to preserve is in the sample. Then with this noise only sample selected, click the "Get Noise Profile" button in the Noise Removal dialog. When that's done select the whole track, adjust the sliders under "Step 2", then "OK". I've never used a noise reduction as high as 24dB, normally I set it around 9dB - 12dB. But then again, I'm normally processing audio from a recording of an LP, not a noisy voice track. Some experimenting with noise samples and the control sliders is undoubtedly called for.

I once did make a usable version of a low volume, noisy cassette recording of an interview of my wife's father. To get anything at all I used noise removal, equalization similar to what Trebor described, and the compressor effect to try even out the volume variations in the voices.

PDX

24dB will not be theatrical. The noise will remain inside each word as its spoken, but the spaces between the words will be clear. This sounds really weird and is the edge beyond which you say you have no show and start over.

Yes, the Capture Profile step is critical. Noise Removal will try to subtract everything in the profile from the show. If you select noise only, only the noise will go away. If you capture some of the voice by accident, the voice will go away, too.

This is a Big Problem on a very noisy show. Sometimes, you capture voice with the noise because the noise is so loud you can't tell the noise isn't alone. This will really mess up your reduction job and you won't be able to tell why.

Sometimes, you can select some Noise by itself and apply Amplification before you capture the profile. This gives Noise Reduction more to chew on and sometimes gives you better results. Be sure to UNDO the amplification later.

Koz

Roxanne1149 wrote:... if it can be fixed.

You could attach a 5-10 seconds of the worst part of the original recording, (before you have attempted to clean it ) to your next post,
and we could tell you if you are flogging a dead horse. Bear in mind anyone can hear and download audio posted in this forum.

Thank you all! PDXRunner, that makes a lot of sense and I will try that immediately to see if that helps. I did not realize I needed to clip a portion without voice on it for the noise profiler to do its job well. I hope I have a portion without voice. Trebor, if I am still floundering, I will post a portion of audio for input from all, but I am embarrassed to say I do not know how to go about that, but before you waste time explaining it to me, I will try the other two suggestions first. I deeply appreciate everyone's time in posting. I know there are a lot of threads and a lot of people needing help. I just started my own business and feel a lot of pressure to get things right and not lose clients!

Roxanne1149 wrote: I did not realize I needed to clip a portion without voice on it for the noise profiler to do its job well.

See the first link in Trebor's first post.

Roxanne1149 wrote: I will post a portion of audio for input from all, but I am embarrassed to say I do not know how to go about that

Select a bit of a audio (click and drag on a track) then "File menu > Export Selection" and export as a WAV file,
Short WAV files (up to about 6 seconds) can be "attached" to a forum post - look below the compose message box for "Upload Attachment".

Thank you so much, Steve! And Trebor, I am sorry I didn't realize I was to open the two links you included above your post in order to help me further.

Here is a sample of how the audio sounds. I am crossing my fingers someone here knows how to fix it, if it can be fixed. The entire piece sounds like this and it's especially bad when the interviewee is speaking. The room the interview took place is a large, cavernous place, which isn't helping.

Thank you again for helping me!

In short the patient is terminal.

It sounds like it was recorded via an echoey tube, like an air-vent or drain-pipe.

Then way too much compression has been applied which has introduced the whistley R2-D2 artifacts.

I’ve attempted to recreate this combination of distortions …
To produce this recreation I used a mp3 bit rate of 8Kbps,
for a comprehensible mono voice recording at 16000Hz sample rate you should use a bit rate of not less than 32Kbps, (I'd use 64Kbps).

Once a recording has been damaged by too much compression (too low a bit rate) it cannot be undone.