FROM SUPPRESSION TO ENHANCEMENT: THE EFFECTS OF SELF-GENERATION ON SENSORY RESPONSES AND PERCEIVED LOUDNESS DEPEND ON SOUND INTENSITY

Self-generated (SG) sounds typically elicit attenuated perceptual and neural responses at clearly audible intensities. However, recent studies suggest a reversal of this effect at near-threshold intensities, with SG sounds perceived as louder than externally generated sounds. Whether these perceptual changes are mirrored by neural responses remains unclear.
This study examined how sound source (self-generated vs. external) and sound intensity (near-threshold vs. supra-threshold) interact to influence auditory processing at perceptual and neural levels. Forty-seven participants performed a two-alternative forced-choice intensity discrimination task. The first sound was either self-generated or externally generated at a fixed intensity, while the second sound was always externally generated and varied in intensity (±3 dB). Psychometric functions were fitted to estimate points of subjective equality (PSE). Concurrent EEG recordings were used to analyze the amplitude of the N1 component evoked by the first sound.
Results revealed a significant interaction between sound source and intensity. Near-threshold sounds evoked weaker neural responses than supra-threshold sounds. At supra-threshold intensities, self-generated sounds showed sensory suppression, whereas at near-threshold intensities they showed sensory enhancement. This interaction was evident in both perceptual measures (PSE) and neural responses (N1 amplitudes). Moreover, self-generation eliminated intensity-related differences in N1 amplitudes, further supporting a direct correspondence between perceptual and neural effects across stimulus intensities.
These findings demonstrate that self-generation effects on auditory processing depend on stimulus intensity and are consistently reflected at both perceptual and neural levels.