Untangling the effect of the reed resonance and tonehole lattice cutoff frequencies on the internal and external spectra of a clarinet-like instrument
Erik Alan Petersen · The Journal of the Acoustical Society of America · 2021
The spectrum characteristics of reed instruments are determined by many factors, some of which are related to musician control and others that are intrinsic to the physics of the instrument. Two such factors are the reed resonance frequency and the tonehole lattice cutoff frequency. The former can be manipulated to some degree by the musician, while the latter is fixed by the geometry of the air column. Although both of these variables are known to impact the spectrum of a woodwind instrument, it is complicated to evaluate the relative importance of their individual contributions, which may present in similar manners. Here, digital synthesis coupled with a simple radiation model is used to untangle the dual effects of these two characteristic frequencies on the internal and external spectra of a clarinet-like instrument. The amplitudes of the even harmonics in the internal and external spectra are boosted at the reed resonance frequency. While the tonehole lattice cutoff frequency also boosts the even harmonics in the internal spectrum, there is an additional overall increase in radiation at the cutoff which emphasizes both the even and odd harmonics in the external spectrum, implying that it may have a larger impact on the perceived timbre.