A jet‐edge‐resonator (JER) whistle consists essentially of a jet‐edge (JE) system, such as may itself produce edge tones, and a resonator. Sound fields generated by such sources are described, as well as dependence of various aspects of these fields on airflow and whistle dimensions. Empirical findings are interpreted in terms of independently determined properties of JE systems and of resonators. A method is described for adjustment of a given whistle to maximum or near‐maximum output for a given frequency. Typical output data so obtained are presented for each of several models. Approximate values are also given of the modulation coefficientMfor various circumstances. This quantity is an index of effectiveness with which steady flow into a whistle is converted into a sinusoidally varying flow out of its mouth.