P. L. Hoekje
Phys. Dept., Univ. of Northern Iowa, Cedar Falls, IA 50614-0150
The lack of a distinct bell at the large end of the renaissance cornett is associated with some unique properties. The typical cornett has a conical shape with a length between 55 and 65 cm, and an open end diameter of 2.5--3.5 cm. Its range is from A3 to D6 (about 220--1175 Hz). With all holes covered, it usually overblows a minor ninth from the first register to the second. Notes with open holes overblow an octave, and adjustment of tone-hole dimensions can bring the ratios of second- to first-mode frequencies close to 2:1 for diatonic scale notes. Besides benefitting tuning, this also improves low register response due to intermode cooperation. The cutoff frequency of the tone-hole lattice is typically between about 600 and 900 Hz. Higher frequencies pass down the bore but are reflected back at the open end, whose cutoff frequency exceeds 3000 Hz. This sustains several higher modes whose frequencies are strongly affected by the total bore length. The length directly affects the tuning of some third-register notes, and a second-register note can benefit when the bore length is adjusted so that a higher mode frequency lines up with a harmonic of the tone.