Download - Odeon

if changing input signal or BRIR from within this display you may press the Maximize Gain button
to maximize the gain for the new setup.
Relative play back levels
In some cases you'll be interested in obtaining correct relative levels e.g. for comparisons
between different seats in a concert hall. In this case you should remember to use the same
recording level (convolver level and mixer level) in the samples to be compared; it is a good
idea to use the same input Signal file to make sure that levels are the same at this point. If you
wish to compare across different rooms you should also be careful to remember that source
gains in the rooms corresponds. If using the Streaming convolution option available from the main
display in the Joblist, ODEON will maximize the auralisation output level, so if you wish to
compare different setups you should make sure to set the Gain in the Streaming convolution display to
the same value.
Absolute play back levels for headphone auralisation
Setting the level to an absolute level so the subject presented to the auralisation sample
experiences the same level as would have been the case in the real room is a bit tricky as it
involves every part in the signal chain.
To obtain a reasonable correct level a first approach is to adjust the auralisation output
against levels of some kind of sound in the room in which you are, e.g. if you are simulating
voice, try to compare the level of the playback with the level of somebody speaking in your
room. This method should make it possible to make a rough adjustment - and it’s certainly
better than none.
A more precise method is to use the calculated SPL A as a reference (if it is calculated at an
absolute level):
Present the auralisation signal over a loudspeaker in the room in which you are sitting
Measure the sound pressure level in the room at the position where you will be sitting
when listening to the auralisation and adjust the output level of the loudspeakeramplifier
until the measured L Aeq corresponds to the calculated level. At this point you
have a physical reference level, which can be used for calibration of you auralisation
playback level
Change between playing your auralisation sample over headphones and over the
loudspeaker while adjusting the level of the auralisation playback until you are satisfied
that the levels are the same.
This method is somewhat inspired by the old Barkhausen method for measuring loudness level
in Phon and should at least in principle allow perfect calibration of the level (the resulting level
being within one subjective limen).
Headphones
The binaural auralisation results created in ODEON are binaural signals which should be
presented over headphones, the objective being to reproduce the same sound pressure at the
entrance of the ear canals (and at the eardrums for that matter) of the subject as would be
obtained in the real room, if it exists).
Soundcards
A sound card is required in order to play back the auralisation results and may also be useful if
you wish to transfer (anechoic) signals to the hard disk. As a minimum the sound card should
be capable of handling signals in stereo, in a 16-bit resolution at a sampling frequency of
44100 Hz. To transfer signals, without loss in quality to /from a DAT recorder the soundcard
should be equipped with digital input and output and the soundcard should be able to handle a
sampling frequency of 48000 Hz. It should also be considered whether the card is immune to
electromagnetic noise, which is always present in a PC and whether its analogue output for
headphones is satisfactory. (For surround auralisation, obviously a multi channel surround
soundcard is needed along with the necessary loudspeakers and amplifiers).
Input signals for auralisation - anechoic recordings
For auralisation you will be using input signals to convolve with the calculated BRIR's. Usually
the signals will be anechoic signals although it may also be other types of signals, e.g. if you
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