Professional microphones use to be monaural and domestic/computer microphones (like those embedded on laptop's LCD and/or headsets) are stereophonic. In the majority of the cases the sound cards handle these different connections without a hassle but in certain cases the ground cable uses to insert certain harmful noise.
First of all you should consider checking your microphone's cable, and the usage of a balanced stereophonic cable which will take those harmful signals into the ground thus reducing the noise.
But if the noise that your sound device is gathering from the microphone is like a hum or hiss, you must consider amplifying the microphone prior to inserting its signal into the sound card. This is easily done with the usage of an external sound mixer (hardware). The cheapest one will do the trick. This will also allow you to equalize the microphone in order to get the best sound quality for your input.
You must connect the microphone to the mixer, where you will adjust the sound quality, EQ, level and in the computer reduce as much as possible the input level in your sound preferences application/GUI.
- Good level source (hardware) in a good level input (software) = Good
- Good level/Low level source (hardware) in a high level input (software) =
- High level source (distorted) in a good/low level input (software) = Bad
IMPORTANT: 100% Hardware/Software level is not "good level"
High level source (distorted) in a high level input (software) is never recommended.
The best your source level is, you need less amplification in the software part. This will result in a good qualiy sound.
If you can't afford a mixer, or don't have plans to purchase one, try decreasing the input (software) level. This will need you to speak louder in order to compensate the lack of recording signal.
In my case, I am using a Gemini PDM-14 Stereo Preamp Mixer with dual per-channel EQ and individual microphone valve EQ. This piece of art is worth $100.00 US Dollars but this is a 8 input channel in 4 Lines with Master/Booth/Rec outputs. You can get a cheaper microphone mixer for less money.
The information provided right here doesn't read about the plug type (stereo/mono), but having in consideration that the specs aren't that far from the Shure SM58 we can say that the noise is being inserted in the sound card input. You should consider pre-amplifying the source or even enrich the signal (with pre-process) in order to gain quality at the input step.