ExponentialSineSweeps

Exponential Sine Sweeps, often abbreviated ESS, are a signal processing technique used to measure the impulse response of acoustic and electroacoustic systems while simultaneously characterizing nonlinear distortion. The method excites the system with an exponential chirp that sweeps frequency from a starting value f1 to an ending value f2 over a fixed duration, with the instantaneous frequency increasing exponentially over time.

During measurement, the system’s response to the ESS sweep is recorded. Deconvolution with the inverse filter of the sweep—constructed by time-reversing the sweep and applying appropriate amplitude modulation—yields the linear impulse response. Nonlinear distortions generated by the system appear as time-shifted copies of the impulse response, allowing their separation from the linear component in the deconvolved signal.

Origin and development: ESS was introduced by Angelo Farina in the early 2000s as a means to obtain high dynamic-range impulse responses and to distinguish linear from nonlinear behavior in a single measurement. The technique has since become widely used in acoustics and related fields.

Advantages and applications: ESS provides a high dynamic range and effective separation of nonlinear distortion, making it well suited for measuring loudspeakers, rooms, microphones, and musical instruments. It is also employed in diagnostic testing of electroacoustic devices and in the creation of impulse responses for reverberation modeling.

Practical considerations: selecting sweep bandwidth, duration, and end frequencies depends on the device under test; care is taken in designing the inverse filter and in windowing or gating the measured response to isolate relevant components.