Near threshold, masked threshold depends on both masker level and threshold-in-quiet via internal noise

Evidence

Near threshold in quiet, masked threshold becomes dependent not only on masker level but also on level of threshold in quiet. In this case, the masker noise and the internal noise responsible for threshold in quiet have to be added. Using such an assumption, the threshold of tones masked by broadband noises of lower levels changes from the masked threshold into threshold in quiet very smoothly. Threshold in quiet as such can be picked up from this model assuming an internal noise as the masking sound. — Professor Dr.-Ing. Hugo Fastl, Professor Dr.-Ing. Eberhard, Psychoacoustics- Facts and Models, 642

Categorization

• DEFINE: Clarifies that threshold in quiet is modeled as masking by an internal noise source — a conceptual framework worth remembering.