Additivity of masking.

Suppose, in separate experiments, the level of noise and the level of a sinusoid are adjusted so that each produces the same amount of masking of a gated sinusoidal signal. If now the noise and sine‐wave masker are combined, how much must the level of the signal be increased to achieve the same level of masking effectiveness as before? Few conditions require only a 3 dB increment of the signal. It is argued that an increment greater than 3 dB implies that the processing of the signal when masked by noise and when masked by a sine wave are different.