M

Masking
The obscuring or covering up of one sound by another.

Mass
Mass is the fundamental property of a material relevant to sound transmission loss through that material. Generally, the more massive the material, the greater the sound transmission loss.

Mass Law
A law which states that the transmission loss of a barrier is directly related to the barrier’s surface mass. Specifically, the law states that for each doubling of surface mass, or frequency, there is a 6 dB increase in the transmission loss of the barrier.

Mode
A room resonance. Axial modes occur with parallel walls. Tangential with four room surfaces and oblique modes with all six surfaces.

Modal Frequency
The frequency of the normal mode of vibration.