The MLS technique

What is the MLS technique?

A technique for measuring the impulse response of a system using Maximum-Length Sequences, a special type of white pseudo-noise, as stimulus.

What is special about it?

When first presented, it gave the possibility to measure very long impulse responses in, e.g., rooms. At that time, large FFT-sizes were too heavy to calculate on personal computers and the MLS technique had the advantage of employing the very efficient Fast Hadamard Transform.

Today, large FFT sizes are easy to compute and methods such as swept sines (linearly or logaritmically) are possible to use as well. It has been found that the MLS technique is very sensitive to time-variance which can be a problem in large rooms, and definitely in outdoor situations [Svensson and Nielsen 1999].

Links

WinMLS, software using the MLS technique on PCs with ordinary soundcards.

Publications