Masking threshold
![The spectrum of a 1 kHz tone. A sound will not be heard if it is under the threshold in quiet.
This limit changes around the masker frequency, making it more difficult to hear a nearby tone. The slope of the masking threshold is steeper toward lower frequencies than toward higher frequencies, which means it is easier to mask with higher frequency tones.](/Images/godic/202501/26/Threshold22633.gif")
The masking threshold is the sound pressure level of a sound needed to make the sound audible in the presence of another noise called a "masker". This threshold depends upon the frequency, the type of masker, and the kind of sound being masked. The effect is strongest between two sounds close in frequency.