How can I remove noise from an audio recording?

I used to record important technical meetings and demos using Camtasia Studio, using a Mic to capture the speaker voice.

Sometimes we invite attendees by asking them to call us in the meeting, and they would call on a cell phone then we switch it to loudspeaker so we can hear and talk to them and also record the conversation on Camtasia.

The problem I am having now is that playing back those recording produces the regular noise that results from the microphone being close to the mobile phone (the kind of noise you hear when your mobile phone rings and it is near a speaker).

Any advice on removing this noise?

Solution 1:

Audacity would work great to edit out the noise from the cell phone. It has a filter that you can give it a sample of the noise you want to remove and then you can apply it to the recording to remove (as best as it can) the sound from the recording. You will have to probably try it several times to get it right, and it won't remove it completely, but it should help quite a bit.

Audacity also has several other filters and tools to help remove general noise from a recording which should help with the quality as well. Hope that helps.

Solution 2:

Just use ferrite beads on your wiring. Never solve a hardware problem in software if you can avoid it.

Solution 3:

You definitely need some sort of software to filter out the noise. Some of the other answers here can address that.

If you're still doing the recordings and need to stop the cell phone interference, use ferrite beads near the base of each speaker.

By the way, just in case anyone is curious, these can be used for small desktop speakers, too.