Working Group
1.73
Room Acoustics
Auralisation
A valuable tool for the documentation of room
acoustic changes is the so called "auralisation". It is the presentation of
a hearing impression in a room, in most cases in form of a dummy head recording for
presentation via headphones. Such a recording may be generated in a real room by a dummy
head with microphones in the ear canals or by a simulation of the acoustic conditions in a
virtual room. This is the usual case for room acoustical simulations made on a computer.
Virtual dummy head recordings take into account the sound of individual directions
by using so called head related transfer functions (HRTF).
All relevant room information for the
description of the sound path from sender (S) to receiver (R) is included in the
stereophonic impulse response. Nowadays this is easily
measured and simulated by modern computer systems which also enable a convolution process.
Thus random source signals which should be recorded in an
anechoic surrounding (see photo) can be used to calculate the
convoluted sound using the impulse response of the sound path S ---> R. By using stereo
headphones with the correct equalisation the virtual sound can
be listened to as if the listener is located inside the virtual room (see photo). For the simulation of sound propagation from a
source its directivity is taken into account as well.
This auralisation gives us the
possibility of listening into a simulated room and is therefore considered as being
another criterion for the comparison of room simulation software. Sound signals recorded
with low reverberation are convolved at the room‘s impulse response and conditioned
for earphone reproduction like an artificial head recording. Material of the actually
recorded series of sounds in the ELMIA concert hall is
available now.
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