The envelope of the rms deflection of the basilar membrane has been studied by means of a digital computer model simulation. The deflection envelope was observed for equal‐intensity bandlimited noise stimuli centered at a frequency of 300 Hz. Two kinds of noise‐band symmetry were used: arithmetic and geometric. Bandwidth was varied in steps from pure tone to 4 oct. It was found that as the bandwidth of the noise increased, the length of the membrane that exceeded an arbitrary threshold increased quite slowly until a bandwidth of about 100 Hz was reached. The threshold used was 0.5 of the maximum deflection to pure tone. At higher bandwidths, suprathreshold membrane length increased more markedly. When a higher threshold near that of the pure‐tone maximum deflection was employed, the suprathreshold membrane length decreased then increased with bandwidth. Comparison of these results with psychoacoustic studies on loudness and the critical band reveal similarities. They suggest that loudness phenomena may originate peripherally and be associated closely with the extent of the basilar membrane simulated.