Measured dependences of thePfeifentonfrequency on static flow pressure, orifice diameter, and pipe length are presented, based upon studies of air flowing through pipes terminated various orifices. Frequency measurements were made of the vibrations inside the pipe. ThePfeifentöneare not a series of discrete single valued harmonics. Each covers a range of frequencies, any specific value of which is determined by the discharge flow‐velocity or pressure. When the orifice diameter approaches zero the behavior of theprimary Pfeifentonfrequencies is as if they were produced by an open‐closed organ pipe; when the orifice diameter approaches that of the pipe, the behavior is as if they were produced by an open‐open organ pipe. A mechanism for the excitation of thePfeifentöneis proposed.