A SAM tone (Sinusoidally Amplitude Modulated tone) is a type of acoustic stimulus signal commonly used to a specific type of ABR called an Envelope Following Response (EFR). A SAM tone consists of sound at a single frequency, or pitch, whose amplitude is rhythmically increased and decreased over very short time scales (on the order of milliseconds). ABRs that are elicited by SAM tones overlap with each other and fuse into a complex rhythmic response in which the frequency of the ABR waves match the frequency of the amplitude changes of the SAM tone (i.e. an EFR).