Multiphonics in the recorder: Some observations on the effects of selective basis tone removal induced by localized perturbations of window-region air flow
Katherine L. Saenger, Nicholas J. Giordano · The Journal of the Acoustical Society of America · 2024
Multiphonic tones in the recorder are readily produced with certain fingerings and pressure/flow conditions. These tones typically comprise two strong basis tones that do not have a harmonic relationship, along with weaker tones whose frequencies are linear combinations of the basis tone frequencies. In this work, an artificial blower was used to generate multiphonic tones in three recorder body types (each attached to the same Yamaha soprano recorder head): (i) a forked fingering for G5 in a standard tapered body; (ii) a C5 in a cylindrical body; and (iii) a C5 in a capped cylindrical body. It was found that a thin post placed in the recorder's window region could selectively remove one of the basis tones (as well as the combination tones) with little effect on the sound power of the other basis tone. Navier-Stokes simulations were performed to help understand why a post in this position can have these effects. [Work supported by NSF under Grant No. PHY2306035.]