Improving Lateral Fraction Estimation by FIR filtering correction of room impulse responses

The Lateral Fraction (JLF) objective parameter correlates well with the subjective impression of Spaciousness of concert halls and it is not difficult to estimate. The usual way of measuring JLF consist in using a variable pattern microphone with matched gain between omnidirectional and bidirectional patterns. Sources of error of different microphones are shown to be high, especially depending on the spectral content of the lateral reflections and the gain matching process is not clear. This paper introduces an alternative method using a small diaphragm omnidirectional microphone and a bidirectional microphone corrected by the use of a FIR filter to minimize this problem.