Buzzing - removal advice, please

[elDuck]

Hi, I'm running Audacity 1.3.5.

I sometimes do interviews with subject matter experts that I deal with on the phone. Often I can get away with using Skype and then we record the interview on there so that we can use it later to transcribe it or whatever (with the obvious legal stuff like them knowing that there is a recording going on!).

Anyway, on this occasion Skype is not going to be possible but as luck would have it I have a microphone that is meant for recording using a phone... never used it before so this is my first shot.

So the microphone won't pick up anything unless I put my phone on speaker phone mode. Such is life.

I made a few sample recordings but even keeping the phone some distance from the laptop (the mic is plugged straight in to the mic socket on the laptop) there is quite a buzz. Probably something to do with the microphone and phone not playing nicely

I tried removing the buzz using the Noise Removal filter - getting a profile of the buzz and then selecting the whole recording and removing it. The results weren't brilliant.

Here is a sample: first section, no editing, second section edited, and a blank bit at the end to show the buzz.
http://www.studywright.com/test/phone-r ... sample.mp3

Note I've only used Noise Removal on this, nothing else.

Clearly the buzz gets removed from blank sections but it is still pretty evident in the spoken section. I'm thinking that such a buzz is so regular that maybe one of the other filters might be worth looking at - but I'd be well out of my depth to know where to look.

Can anyone tell me how to get rid of this buzz and make a useable recording out of it? If I have to listen to several hours of buzzy recordings I might just go mad!

Thanks.

[steve]

Of course it would be much better if you could reduce the noise at source, but working with what we have.

The first thing that I notice is that the recording volume is very low, (could it have been recorded louder), so we will use the "Normalize" effect and normalise to -1dB

Now select a section of noise and use Ctrl+D to make a duplicate.

Amplify the duplicate noise by 6dB

Select the amplified noise and with the Noise Removal effect, capture your noise profile.

Finally, select the original track and apply Noise Removal with these settings:

32
150
0.10

Here's the result

phone-recording-sample-cleaned.wav.zip

1st half cleaned with method described above

(866.17 KiB) Downloaded 225 times

If you are happy with the result, delete the duplicate noise track and Export your voice track.

[kozikowski]

I'll take the other half.

<<<Probably something to do with the microphone and phone not playing nicely>>>

Probably because you're not using a "Telephone Deskset." That would have worked. You're using a cellphone whose radio transmitter drives other electronics nuts. Headsets and other cellphone accessories are all designed to suppress and shield against radio interference. We have one computer system at work that can tell if someone has a cellphone within 50 feet. It doesn't have to be ringing or working, either. Just waiting for a call.

Skype and Vonage seem to be the answer, but it's difficult to record both sides of an internet phone call. One company makes their own software and the other uses the full license of Pamela.

Recording a phone call has always been a challenge starting about 1948. I ripped my cellphone apart once and figured out what all the external connections do when you plug a headset in. That's when I ran into that stu--BZZZZZZZZZZ-TICK TICK TICK TICK BZZZZZZZZZZmmmm --adio interference problem.

Sometimes you can get equipment designed to plug into a cellphone. That can be made to work really well. Google time.

Koz

[elDuck]

Steve - that's a huge improvement. That should allow me to do the job I need to. That was as loud as I could record it yesterday but I've a few ideas for getting better contact with the phone that might help (I'll be testing those today).

Koz - you're almost right. The phone is not a true cellphone, but it is a digital portable phone with a base station that it transmits to, so not a corded desk phone. What you say therefore makes heaps of sense. I've tried a few different phones over the years and I find all of them buzz to my ear... let alone to a microphone! This is the clearest one I've had so far but it is the first time I've tried to record it.

Thanks both. I have a solution that will do the job.