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 20,000 Hz. 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 pipeNumber of over tones =( No. of mode of vibration )−1                                      =7−1=6