Need help amplifying low voices.

Hello. I have a recording of a neighbor making threats about me to his roomate. I was in my apartment at the time shooting some video and you can hear him yelling in the background from his apartment. I need to provide this evidence to the Police and my landlord. Any help is much appreciated.
Threats 7-18-16.aup (8.99 KB)

We can’t open an AUP file because it’s only your project “index” file and there’s no audio in it. Try exporting & posting an MP3 or WAV.

But… Your ear & brain are a pretty good filter. If you (or the Police) can’t understand what’s being said, software probably won’t be much help. The stuff you see in movies and on TV where they pull a conversation out of crowd noise at a party, etc., is mostly science fiction.

And, if you alter the evidence it probably can’t be used in court (although it could be useful to the police).

Couldn’t get either to upload…please follow ling to Google Drive:

Sorry but there is no way to recover anything meaningful from that noise.

Also, please note that as a matter of policy, we are not able to offer an audio forensics service.
In this case I very much doubt that even a professional audio forensics expert would be able to recover anything meaningful from that noise.

Well lets say this is a forum where people seek help in using Audacity in improving the audio content. What is the best way to filter out background noise and amplify low tones, say like voices? Thank you in advance to anyone who offers useful advice.

For low level noise, “Noise Reduction” can be very effective

For low frequency noise (rumbling), a high pass filter can be very effective

For high frequency noise, a low pass filter can be effective, but is likely to also make the speech sound muffled.

For constant pitched whisle/hum sounds, a notch filter can be very effective. Looking carefully at the spectrogram or using Plot Spectrum can help to determine which frequencies need to be notched out.

See also:

For higher level noise, the “Telephone” preset in “Equalization” may give some benefit, but that’s about as good as it gets (and it probably won’t help very much).

If the noise is so loud that the speech can’t be heard, then it’s a lost cause, the speech can’t be recovered.

For more information about noise reduction techniques, see this article:

Thank you.