ABSTRACT
A signal is a varying parameter that represents information. It has the same frequencies and the same amplitude changes as the incoming sound wave. Polarity is not the same as phase or phase shift, which refers to a delay between two identical signals. Noise is another characteristic of audio signals. Every audio component produces a little noise, a rushing sound like wind in trees. To hear distortion, simply record a signal at a very high recording level and play it back. Digital recorders produce "quantization" distortion at very low signal levels. Every audio component works best at a certain optimum signal level, and this is usually indicated on a level meter built into the device. The greater the headroom, the greater the signal level the device can pass without running into distortion. If an audio device has a lot of headroom, it can pass high-level peaks without clipping them.
