Need help with Noise Reduction/ Enhancing Vocals on Digital files

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dipen01

dipen01

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Hey guys,

I recorded few lectures with my cellphone (SE W595). I converted the amr files to mp3. Now the thing is that there is extreme noise and vocals are hardly clear.

So I was hoping to get some inputs as to how I can improve the quality of the sound.

I have attached a small sample of the file:

YouSendIT

I tried fiddling with Audio Editor Gold, without any discernible results.

So any help on the same is appreciated. All I expect is decent level of vocals.

Regards,
 
I couldn't download your Yousendit link, though Ive done this before. It requires a lot of patience - and preferably, access to a spectral editing tool like the one built into Adobe Audition. The problem is that noise is broadband in nature, so reducing the noise levels will take out some of the audio information as well. For each lecturer you will have to see which frequency ranges are used and clip out the rest to a low level (say -30dB). If you take it out entirely you will have some intelligibility issues because human voice also has a large harmonic range.

In the days before Audition etc I used to do it by ear, it was extremely time-consuming but the material was critically important (baby recordings, poems read by my parents and recorded on a cassette tape) so I managed a decent set. Basically I recorded the tape off the heads and did the correction, applying EQ after I was done. I remember removing most of the range above 2KHz and below 300Hz, and using a noise gate at about -20dB (or maybe -30dB) to remove the noise. After this was done I compressed the signal a bit (about 3:1) and applied the NAB tape EQ. This took care of most of the noise. The speech was clear enough to be understood, a pretty big improvement over the originals.

Cellphones are worse. You can expect a S/N ratio of about 6-12dB (cassette tape is about 40dB, with the better players reaching 60dB), as they are optimised for close pickup and not ambient. Also the automatic level control increases the gain when the sound source is far away, increasing the noise further. To start with I would use a noise gate and see where the noise is. If possible, open the wave/mp3 file in Audacity and post a screenshot, let's see how bad the situation is. Looking at it will help more than hearing.
 
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