Digital room correction

Digital room correction is a fairly new area of study which has only recently been made possible by the computational power of modern CPUs and DSPs.

The spectrum is then smoothed, and a filter set is calculated, which equalizes the sound pressure levels at each frequency to the target curve.

To calculate the delays and other time-domain corrections, an inverse Fourier transform is performed on the spectrum, which results in the impulse response.

Room correction filter calculation systems instead favor a robust approach, and employ sophisticated processing to attempt to produce an inverse filter which will work over a usably large volume, and which avoid producing bad-sounding artifacts outside of that volume, at the expense of peak accuracy at the measurement location.

REW also features IR windowing, and SPL meter, room simulation for subwoofer placement, and peaking filter-based EQ generation for multiple platforms, DSPs, and AVRs with a target curve editor.

QuickEQ supports multichannel measurements with multiple microphones, time and level alignment with multiple standards and target curves, IR windowing, multi-sub crossover, and experimental filters for increasing speech intelligibility and simulating other cabinet types.

Dirac Live is a commercial software that is available for PC and select Onkyo, Pioneer, Integra, StormAudio, and other AVRs.

Notable examples are IMAX cinemas, which use Audyssey MultEQ XT32,[2] while Datasat processors (found in all DTS:X rooms) have Dirac software.