Frequency response refers to how a system, such as an audio device or a filter, reacts to different frequencies of input signals. It is typically represented as a graph showing the output amplitude versus frequency. This helps in understanding how well the system reproduces various sound frequencies, which is crucial in fields like audio engineering and telecommunications. In practical terms, a good frequency response means that the system can accurately reproduce sounds across a wide range of frequencies without distortion. For example, in loudspeakers, a flat frequency response indicates that all frequencies are amplified equally, resulting in clear and balanced sound reproduction.