Science Fair Project Encyclopedia Frequency response is the
measure of any system's response to frequency, but is usually
used in connection with electronic amplifiers and similar
systems, particularly in relation to audio signals. Because the
human ear is generally not sensitive to phase, the frequency
response is typically characterized by the magnitude of the
system's response, measured in dB, versus frequency. The
frequency response of a system is typically measured by applying
an impulse to the system and measuring its response (see impulse
response), sweeping a pure tone through the bandwidth of
interest, or by applying a maximum length sequence. Once a
frequency response has been measured (e.g., as an impulse
response), providing the system is linear time invariant, its
characteristic can be approximated with arbitrary accuracy by a
digital filter. Similarly, if a system is demonstrated to have a
poor frequency response, a digital filter can be applied to the
signals prior to their reproduction to comp