Auditory Masking

Auditory masking is also known as frequency masking

It occurs when a sound that we can normally hear is masked by another sound with a nearby frequency.

This type of masking is also called simultaneous masking as both sounds occur simultaneously.

The following figure illustrates Auditory masking:

The Red flick arrow in the above diagram at 8 KHz represents a strong sound source.

This source raises normal threshold in its vicinity such that the nearby sound x is masked and is inaudible.

This masking of the other sound in the vicinity of a high frequency sound is frequency masking/ Auditory masking.

Temporal Masking

Temporal masking may occur when a strong sound A of frequency f is preceded or followed in time by a weaker sound B at a nearby (or the same) frequency.

If the time interval between the sounds is short, sound B may not be audible. Figure 2b illustrates an example of temporal masking

The threshold of temporal masking due to a loud sound at time 0 goes down, first sharply, then slowly. A weaker sound of 30 dB will not be audible if it occurs

10 ms before or after the loud sound, but will be audible if the time interval between the sounds is 20 ms.