 In addition to band-stop filters (also known as "notch filters"), low-pass filters, and high-pass filters for filtering out hum and noise, many applications allow the user to take a "noiseprint" of a small section of waveform when the stylus is tracking but no music is playing; the filtering is then accomplished specific to this noiseprint.Second, there are the transient bursts of damage, mostly clicks and pops, caused by scratches or record defects, and crackle caused by lots of minute defects grouped close together.The software must filter this kind of click-pop damage conservatively, because a click or a pop can look very much like a legitimate percussive effect, such as a light snare drum rim-shot.