All recordings, no matter how they were created, contain some amount of noise. Noise is only a problem if the level is high enough to affect the sound you actually hear. Louder music can mask higher levels of noise than quieter sounds (see Chapter 10 for an explanation of the threshold of hearing and the masking effect). This means that the same level of noise would be less of a problem in rock or heavy metal music than it would be in new age or folk music.
Often you will find several types of noise in a recording and will need to process it in several stages. Generally, it’s best to remove noise that occurs throughout the audio file, such as hum and hiss, first, and then remove impulse noise, such as clicks and pops. Why? It’s easier to do the global processing first, and once that’s done, it’s easier to see and hear the impulse noise.
Many recordings from analog sources—such as records or tapes—will have noticeable background noise, including hiss, clicks, and pops. Hiss is more of a problem with tapes, but it will also show up on most vinyl LPs. (Of course, if the music masks the noise, you don’t need to remove it.)
Noise reduction always involves tradeoffs, and often it can end up doing more harm than good. It’s much easier to minimize noise when you make an original recording than to remove it after the fact (see Chapter 11 for tips on minimizing noise). If you’ve done everything you can to minimize noise during recording, or you have material ...