An organ pipe is closed at one end has fundamental frequency of 1500 Hz. The maximum number of overtones generated by this pipe which a normal person can hear is :

Critical hearing frequency for a person is 20,000Hz.  If a closed pipe vibration in Nth mode then frequency of vibration n=(2N−1)v4l=(2N−1)n1(where n1 = fundamental frequency of vibration)Hence 20,000 =(2N−1)×1500⇒N=7.1≈7Also, in closed pipe Number of over tones = (No. of mode of vibration) –1                                    = 7 – 1 = 6.