Amplitude modulation. AM alters the amplitude of signals according to a rate set by a low frequency oscillator. In simpler terms, AM raises and lowers the volume of a signal at a set rate.
Describes how quickly the compressor responds to increasing input level. A very fast attack prevents transients from “passing under the radar” of the compressor, and is useful for softening transients of instruments like snares. A slower attack preserves transients.