Thresholds of detection for changes to the Q-factor of low frequency modes in listening environments

Abstract

An investigation into the measurement of the thresholds of detection of modal Q factors in rooms at low frequency is measured. Key features of the approach taken include the use of music rather than test tones or noise as program material, and the manipulation of damping conditions for a range of modes over a broad low-frequency bandwidth as opposed to the control of one modal artifact within an array of surrounding uncontrolled resonances. It is shown that the detectability of Q-factor changes is directly proportional to the reference Q, and is weakly dependent on the presence and level of higher frequency reverberations. A threshold value of Q = 16 is suggested, below which further changes are unlikely to be detected.