Microphone noise or signal noise is an unwelcome annoyance when recording, in most cases taking a few simple steps can help to reduce or remove this altogether. Try these steps in the order in which they are listed.
Check your input (where the microphone is plugged in) you may have plugged your microphone cable into the line input jack rather than the microphone jack, switching this over will remove unwanted noise.
Check your cable. It could be a damanged or poor quality cable that is causing your microphone to generate noise. If you can try a new or different cable this way you will be able to see if the noise is being generated by the cable or is coming from a different source.
Signal to noise ratio. This mean that the higher you turn up your gain (microphone input level) the higher the electrically generated noise will become. Try this out turn your mic gain up to full and you will be able to hear a low level hiss/white noise.This noise is caused by all the electrical processes going on within your hardware, the electrical noise level will depend on the quality and condition of your equipment. The best way to combat signal noise is to manage your recording levels. Make sure your sound source is in close proximity to the microphone, check your recording level is set correctly (so that the input is loud but not so loud that is will peak or go red!) and finally make sure there are no other sound sources to ‘muddy up’ your recording.
Get the gear. Don’t rely on the microphone built into you new laptop/PC or the old karaoke microphone kicking around in your house. Built in microphones are great for skype or webcasts but they will not deliver high quality audio and will will most likely also create a good deal of signal noise or make your sound very thin without any of the warmth your recording really needs. It is important to get a microphone worthy of the effort you are putting into your recordings and the higher the microphone quality the more likely the noise to signal ratio will be reduced (ahhh clear audio)
Microphone owners would do well to check their microphone type. Microphones that are less likely to produce microphone noise are of the electret condenser variety. To determine whether a microphone is a electret condenser, one should look at the microphone plug and find the tip part of the plug. If the microphone tip is silver and has grooves dividing the plug into three, then the microphone is an electret condenser that can easily connect to a computer’s sound card. Dynamic microphones, on the other hand, may present problems with microphone noise due to increased sensitivity and issues with connecting to soundcards.
Noise reduction software and audio recording software. Getting the right software can also help software designed to help you rercord using external microphones will further help your cause and if you are stuck using a cheap microphone software with built in noise reduction effects (like audacity) could also help to purify your recording.