Optimal modal spacing and density for critical listening

This paper presents a study on the subjective effects of modal spacing and density. These are measures often used as
indicators to define particular aspect ratios and source positions to avoid low frequency reproduction problems in
rooms. These indicators imply a given modal spacing leading to a supposedly less problematic response for the
listener. An investigation into this topic shows that subjects can identify an optimal spacing between two resonances
associated with a reduction of the overall decay. Further work to define a subjective counterpart to the Schroeder
Frequency has revealed that an increase in density may not always lead to an improvement, as interaction between
mode-shapes results in serious degradation of the stimulus, which is detectable by listeners.