In order to achieve good quality audio, sound level monitoring/altering should be carried out. Sound levels too close to the noise floor (the lowest level of recording) will result in a poor quality recording with hissing and humming being quite prominent in most cases. When recording, recording as close to the Permitted Maximum Level (PML) as possible, without reaching or exceeding that limit will result in optimal recording levels. Reaching or exceeding this limit will result in distortion of the signal. This is when the levels 'peak' and results in audio 'clipping'. Modern digital audio can record very close to the peak levels without distorting, however monitoring when recording is required to avoid distortion.
When recording audio, a comfortable range for your peaks should be found (usually between -12 dB and -6 dB) before any recordings are made. A recording with peaks set lower than this (around -16 dB and below) will leave a greater amount of noise when the audio has to be boosted after to reach optimal levels. To set these levels, manual level control on the microphone of choice should be used. Automatic level setting can be used on modern microphones, however this usually leaves for the change in levels during the recording, and noise becomes more prominent during silence.
