End Corrections of Organ Pipes
Arthur Taber Jones · The Journal of the Acoustical Society of America · 1941
This is an experimental study of the end corrections of two rectangular wooden pipes, each wide open at one end and partly closed in various ways at the other. The pipe to be examined was excited by a telephone receiver set into one side of the pipe, and the sound was picked up through a small bore brass listening tube screwed into another side of the pipe and connected by rubber tubing to the observer's ear. The telephone receiver was fed from an audiofrequency oscillator, the frequency of which was varied to obtain the maximum resonant response. Equations for the frequency of a partly closed pipe have been suggested by several investigators. The present experiments show that not more than one of these equations is satisfactory for any extended range of apertures. The one possible exception is an equation developed by Rayleigh and by Richardson, and for this equation the present experiments are not conclusive. Incidentally attention is drawn to the restriction which a wall near an opening imposes on the flow of air through the opening, and the consequent effect on the natural frequency of an adjacent cavity. It is also found that the fundamental resonant frequency of an organ pipe may be either above or below the frequency obtained by blowing.