preemphasis

or pre-em·pha·sis

[ pree-em-fuh-sis ]
/ priˈɛm fə sɪs /

noun Electronics.

a process of increasing the amplitude of certain frequencies relative to others in a signal in order to help them override noise, complemented by deemphasis before final reproduction of the signal being received.

Origin of preemphasis

First recorded in 1940–45; pre- + emphasis