Fig 1.
Experiment design and Results.
(a) Subjects were presented with two tones and had to decide which tone was louder. In the active condition subjects triggered the first tone by a button press whereas the second tone was generated by a computer (top); in the passive condition, both tones were generated by a computer (bottom). (b) Mean % trials in which 1st tone was reported being louder (error bars denote s.e.m. across 28 subjects). Perceived loudness of self-generated sounds is differently modified by the sound intensity (repeated measured ANOVA, p<0.05). The asterisks denote significant differences between corresponding active and passive conditions within each sound intensity (p<0.05 one-tailed paired t-test).