Perception of modal distribution metrics in critical listening spaces—dependence on room aspect ratios

The subjective significance of two general types of metrics used to describe the “quality”
of a room based on its aspect ratio are compared. Tests were carried out to evaluate differences
between three virtual rooms that score extreme classifications in each of the metrics.
The results of the tests indicate that room aspect ratios do have some effect on the perception
of the modal distribution, but the effect is very much dependent on the frequency content of
the original signal. This indicates that a room that scores well using a certain metric may still
suffer from problems if the frequency content of the driving signal matches one particularly
strong modal artifact. More significantly, the results of these tests imply that attempts to rank
critical listening spaces based on modal distribution metrics are likely to be highly misleading;
and the derivation of difference limen, which would be required for useful comparison,
has been shown in practice to be highly problematic and perhaps meaningless.