Masking noise raises the loudness threshold and fades audible tones

Evidence

When the test sound is partially masked due to the presence of white noise, the perceived loudness of the signal is also affected, as shown in Figure 10.10. The threshold above which Equation (10.2) holds rises with the level of masking noise. When the level of the masker is increased, the loudness level of the tone decreases gradually before becoming inaudible. — Ville Pulkki, Matti Karjalainen, Communication Acoustics- An…, 1138