removing background noise -Sound Forge - PC - MAGIX Community Forums Archive

Subject:removing background noise Posted by: wtharp007 Date:10/23/2000 12:14:00 PM I have been recording two acoustic guitars and two voices simultaneously with one Shure SM58 microphone hanging from the ceiling, plugged into a guitar preamp, and then run into the sound card on my computer (actually the microphone jack on my laptop). With this setup, I get background noise of a fish tank's ventilation system and the hum of a light fixture. I was wondering if there is any way that I can remove these sounds that are not acute, but are constant sounds at the same frequency throughout the entire selection. I know that this is not the best setup for this type of recording, but I am doing the best that I can with the financial constraints that go along with being a college student. I would really appreciate some help because I am very excited with the music that we have, but the whirr and hum of the background noises make this recording very unprofessional. I hope that you can help. wtharp007
Subject:Re: removing background noise Reply by: Rednroll Date:10/23/2000 4:52:00 PM Wow, I'm actually surprised with your technique of recording that those are the only problems you're having. Well first of all you're using an SM58 and you should learn how to use it correctly. An SM58 has a cardiode pickup pattern, What this means is that it picks up sounds the best when the mic is directly pointed at the sound source (this is obvious). More importantly though, is that 180 degrees from the front is the "rejection" of the microphone. Here is the proper guidelines in micing a sound source in there order of importance. 1.POINT THE REJECTION OF THE MICROPHONE AT WHAT YOU "DON'T WANT TO PICK UP!!!!!!" Let me repeat the importance of this...POINT THE BACK AT WHAT YOU DON'T WANT TO PICKUP!!!! (In your case the fish tank and the buzzing lights) 2. Point The front of the Mic at what the intended sound source is. The SM-58 still picks up pretty well from it's sides, only 3dB lower from the front which isn't much. It is more important to reject the noises that you don't want to pick up!!!! This should greatly reduce the unwanted noises with no cost. You also want to make sure that you have no tape wrapped around the handle of the microphone. The SM58 has ports on it near the top of the handle which, makes this mic pickup with this cardiode pattern, if you wrap tape over these ports you essentially make the mic OMNI directional, which means it picks up the same from "All" directions. The other thing you might want to look into is the Sonic Foundry Noise Reduction plugin...(this is not cheap for a college budget). But you can sample a section of background noise with this plugin and tell it how much to reduce "this sampled" noise by....This plugin works really well for constant tones like lights and cassette hiss. It takes some knowledge to use it to it's full potential, but you're a college student and should have no problems with it. Other things you might want to try is pluging the line out of your amp into the line In of your PC if it has one, I'm actually surprised you haven't run into a constant buzz noise or distortion going into the "Mic In" with your current SETUP. If you Don't have a Line out of the amp, then take the speaker out and plug that into the "Line In" of the PC and turn your volume up. This will give you a better Signal to Noise Ratio and may leave the background noises unnoticable. William Tharp wrote: >>I have been recording two acoustic guitars and two voices >>simultaneously with one Shure SM58 microphone hanging from >>the ceiling, plugged into a guitar preamp, and then run >>into the sound card on my computer (actually the microphone >>jack on my laptop). With this setup, I get background >>noise of a fish tank's ventilation system and the hum of a >>light fixture. I was wondering if there is any way that I >>can remove these sounds that are not acute, but are >>constant sounds at the same frequency throughout the entire >>selection. I know that this is not the best setup for this >>type of recording, but I am doing the best that I can with >>the financial constraints that go along with being a >>college student. I would really appreciate some help >>because I am very excited with the music that we have, but >>the whirr and hum of the background noises make this >>recording very unprofessional. I hope that you can help. >> >>wtharp007

Wow, I'm actually surprised with your technique of recording that
those are the only problems you're having. Well first of all you're
using an SM58 and you should learn how to use it correctly. An SM58
has a cardiode pickup pattern, What this means is that it picks up
sounds the best when the mic is directly pointed at the sound source
(this is obvious). More importantly though, is that 180 degrees from
the front is the "rejection" of the microphone. Here is the proper
guidelines in micing a sound source in there order of importance.

1.POINT THE REJECTION OF THE MICROPHONE AT WHAT YOU "DON'T WANT TO
PICK UP!!!!!!" Let me repeat the importance of this...POINT THE BACK
AT WHAT YOU DON'T WANT TO PICKUP!!!! (In your case the fish tank and
the buzzing lights)

2. Point The front of the Mic at what the intended sound source is.

The SM-58 still picks up pretty well from it's sides, only 3dB lower
from the front which isn't much.
It is more important to reject the noises that you don't want to pick
up!!!! This should greatly reduce the unwanted noises with no cost.
You also want to make sure that you have no tape wrapped around the
handle of the microphone. The SM58 has ports on it near the top of
the handle which, makes this mic pickup with this cardiode pattern,
if you wrap tape over these ports you essentially make the mic OMNI
directional, which means it picks up the same from "All" directions.

The other thing you might want to look into is the Sonic Foundry
Noise Reduction plugin...(this is not cheap for a college budget).
But you can sample a section of background noise with this plugin and
tell it how much to reduce "this sampled" noise by....This plugin
works really well for constant tones like lights and cassette hiss.
It takes some knowledge to use it to it's full potential, but you're
a college student and should have no problems with it.

Other things you might want to try is pluging the line out of your
amp into the line In of your PC if it has one, I'm actually surprised
you haven't run into a constant buzz noise or distortion going into
the "Mic In" with your current SETUP. If you Don't have a Line out
of the amp, then take the speaker out and plug that into the "Line
In" of the PC and turn your volume up. This will give you a better
Signal to Noise Ratio and may leave the background noises unnoticable.

William Tharp wrote:
>>I have been recording two acoustic guitars and two voices
>>simultaneously with one Shure SM58 microphone hanging from
>>the ceiling, plugged into a guitar preamp, and then run
>>into the sound card on my computer (actually the microphone
>>jack on my laptop). With this setup, I get background
>>noise of a fish tank's ventilation system and the hum of a
>>light fixture. I was wondering if there is any way that I
>>can remove these sounds that are not acute, but are
>>constant sounds at the same frequency throughout the entire
>>selection. I know that this is not the best setup for this
>>type of recording, but I am doing the best that I can with
>>the financial constraints that go along with being a
>>college student. I would really appreciate some help
>>because I am very excited with the music that we have, but
>>the whirr and hum of the background noises make this
>>recording very unprofessional. I hope that you can help.
>>
>>wtharp007