Recorded conversations

[crimlawfed]

My name is Jon May. I am a criminal defense attorney in Fort Lauderdale and I am having a problem understanding conversations recorded at locations where there is a great deal of background noice, such as at restaurants. These recordings were made by a government informant. My guess is that a graphic equalizer would help me to remove some of the background noice and bring up some of the soft voices. Any suggestions.

[The Ghost of FM]

My suggestion would be transfer your recording to a digital format where you can see a graphical analysis of the subjects frequency range and remove all those areas of sound that are above and below the subject's area of sound.

An analog 1/3 octave eq might do the trick if you must keep the tape in it's original format for evidensary purposes and if so, a trained ear is worth hiring to filter out the sounds you don't need and amplifying the ones you do.

Consulting a legal peer would also be prudent in ascertaining the legality of altering a sound recording and still having it be admissible in a court of law.

Cheers!

[Blue Bear Sound]

And for the future - try and use a very directional mic... Sennheiser has shotgun mics that will focus on a specific point and minimize sounds outside that point.

[crimlawfed]

Thanks for your suggestions.

[Beck]

I'm assuming the recording was made on cassette or micro-cassette tape. Even if it is a small digital recorder some of this will apply.

I did some work about 6 years ago in a couple of cases for a police detective friend. One was to help identify a voice in a phone threats/stalking case. The caller was kind enough to leave the obscene threats on an answering machine. He used a pay phone so there was a lot of traffic in the background. He also altered his voice with a cheap voice-masking device (pitch transposer).

One source of noise to overcome is the hiss of the tape itself and other electronic noise produced by the recording device. I used a Hush IICX single ended noise reduction unit to get that noise level under control. I then used an Alesis MEQ 230 1/3 octave equalizer to bring his voice well above the background. Finally, I used the pitch transposer of a Yamaha SPX-90 to reverse the voice masking.

The female victim recognized the voice as that of a former coworker. I am told the suspect was very surprised to hear the threats he had made unmasked and clear as a bell in his normal voice.

I suggest you contact a local recording studio in Ft. Lauderdale for assistance. Or you can send me a copy on cassette, or CD, or send me a wav or mp3 and I will be able to tell you what can be recovered from the recording.

Tim