Knowledge that an ear is covered reduces loudness summation

Evidence

Since the Silence and Virtual-Finger conditions of experiment 2 produced significantly different summation effects, it seems that a portion of the loudness constancy effect observed in experiment 1 may have been mediated by the residual sound at the occluded ear. Both the Silence and the Virtual-Finger conditions produced a collapse in externalisation for the monaural case, so it seems unlikely that the difference in effect can be attributed to this cause. On the other hand, 2.5–3 dB of summation was still observed in the Virtual-Finger condition, whereas less that 1 dB was observed in the Loudspeaker condition of experiment 1. It appears, therefore, that the listeners’ awareness of meatal occlusion, which would only be present in the first case, may still play a role. — Dijk, Pim van, Physiology, Psychoacoustics and…, 1525

Categorization

• DEEPTHINKING: The finding that cognitive awareness of occlusion — not residual sound — drives most loudness constancy overturns a purely peripheral account of binaural summation, implicating top-down processing in a supposedly sensory phenomenon.