 The sound is thus recorded at a higher overall level on the tape relative to the tape's overall noise level, requiring the tape formulation to preserve this specially recorded signal without distortion.On playback, the opposite process is applied (deemphasis), based on the relative signal component above 1 kHz.Thus as this portion of the signal decreases in amplitude, the higher frequencies are progressively more sharply attenuated, which also filters out the constant background noise on the tape when and where it would be most noticeable.