RESPONSE from ACOUSMONIUM by TELEKINETT / MAURICIO REYES

Frequency response is the quantitative measure of the output spectrum of a system or device in response to a stimulus, and is used to characterize the dynamics of the system. It is a measure of magnitude and phase of the output as a function of frequency, in comparison to the input. In simplest terms, if a sine wave is injected into a system at a given frequency, a linear system will respond at that same frequency with a certain magnitude and a certain phase angle relative to the input. Also for a linear system, doubling the amplitude of the input will double the amplitude of the output. In addition, if the system is time-invariant (so LTI), then the frequency response also will not vary with time. Thus for LTI systems, the frequency response can be seen as applying the system's transfer function to a purely imaginary number argument representing the frequency of the sinusoidal excitation.

Two applications of frequency response analysis are related but have different objectives.

For an audio system, the objective may be to reproduce the input signal with no distortion. That would require a uniform (flat) magnitude of response up to the bandwidth limitation of the system, with the signal delayed by precisely the same amount of time at all frequencies. That amount of time could be seconds or weeks or months in the case of recorded media.

Mauricio Reyes is a futurist, composer and audio researcher focused on experimental, electronic, and electroacoustic practices.

Founder of Telekinett Records (2004–2008), a label dedicated to atonal and exploratory sound, he investigates signal behavior, noise systems, and spatial perception through granular synthesis, tape manipulation, spectral analysis, and circuit experimentation.