What Happens When fD approaches
fCR
In summary then, When f surpasses the so called limit of frequency discrimination
fD, we distinguish two separate tones. However at that limit the sensation of roughness
still persists, especially in the low pitch range. Do not confuse
fD with the limen of frequency
discrimination, the JND for pitch.
Only after surpassing a still larger frequency difference fCR called the critical band, the
roughness sensation disappears and both tones sound smooth. This transition from
roughness to smoothness is gradual.