Experiment design and Results.

<p><b>(a)</b> 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>(b)</b> Mean % trials in which 1^st 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).</p