Partial masking steepens the loudness function in a way that mirrors hearing recruitment

Evidence

A white noise with a density level of 30 dB shifts the threshold in quiet to a masked threshold in such a way that a I-kHz tone of 50 dB sound pressure level is just audible in the noise. This means that the loudness of this I-kHz tone, which in unmasked conditions would be 2 sone, decreases to 0 sone. When the level of the I-kHz tone is increased to 80 dB, the loudness of the tone is close to the loudness produced in unmasked conditions. This means that the masking sound not only produces a shift of the threshold in quiet to masked threshold, but also produces a masked loudness function that has to be steeper than the unmasked loudness curve. … Above masked threshold, loudness rises very steeply and, at levels about 20 to 30 dB above masked threshold, almost reaches the unmasked loudness. … This means that partial masking produces a loudness function that is comparable to that described by audiologists as recruitment. — Professor Dr.-Ing. Hugo Fastl, Professor Dr.-Ing. Eberhard, Psychoacoustics- Facts and Models, 1216

A white noise with a density level of 30 dB shifts the threshold in quiet to a masked threshold in such a way that a I-kHz tone of 50 dB sound pressure level is just audible in the noise. This means that the loudness of this I-kHz tone, which in unmasked conditions would be 2 sone, decreases to 0 sone. When the level of the I-kHz tone is increased to 80 dB, the loudness of the tone is close to the loudness produced in unmasked conditions. This means that the masking sound not only produces a shift of the threshold in quiet to masked threshold, but also produces a masked loudness function that has to be steeper than the unmasked loudness curve. A so-called partial masked loudness curve is produced. — Professor Dr.-Ing. Hugo Fastl, Professor Dr.-Ing. Eberhard, Psychoacoustics- Facts and Models, 1216

Categorization

• DEFINE: Explains the mechanism of partial masked loudness and links it to the audiological concept of recruitment.
• corroborated: 3 independent passages support this claim — Professor Dr.-Ing. Hugo Fastl, Professor Dr.-Ing. Eberhard, Psychoacoustics- Facts and Models, 1216