Frequency Response
Definition
A measurement of how accurately a device — microphone, speaker, amplifier, or headphone — reproduces different frequencies. A flat frequency response means all frequencies are reproduced equally; a colored response emphasizes or de-emphasizes certain ranges.
In Simple Terms
How accurately a speaker, microphone, or headphone reproduces all frequencies — from deep bass to high treble. A flat response means it doesn't add color; what you record or hear is what's actually there.
In Practice
Studio monitor speakers are designed for the flattest possible frequency response so engineers hear the true tonal balance of their mix without the monitors adding their own character.