The dual influence of the reed resonance frequency and tonehole lattice cutoff frequency on sound production and radiation of a clarinet-like instrument.

The internal and external spectra of woodwind reed instruments are partially determined by the tonehole lattice cutoff and reed resonance frequencies. Because they can impact the spectrum in similar ways, a study of one without accounting for the other risks incomplete or false conclusions. Here, the dual effects of the cutoff and reed resonance frequencies are investigated using digital synthesis with clarinet-like academic resonators. It is shown that the odd and even harmonics have similar amplitudes at and above the cutoff frequency or reed resonance frequency, whichever is lowest. However, because the resonators radiate efficiently at the cutoff, it has the additional role of reinforcing the amplitude of both the odd and even harmonics in the external spectrum. The spectra are analyzed using the single value descriptors playing frequency, spectral centroid (SC), odd/even ratio (OER), and brightness as a function of the musician mouth pressure. Higher reed resonances correspond to higher values for all descriptors. The OER and brightness increase with resonator cutoff frequency, whereas the SC exhibits more complicated trends. The reed resonance has a larger impact on the "playing condition oscillation threshold," implying that it may have a more important role in sustaining auto-oscillation.

The bassoon tonehole lattice: Links between the open and closed holes and the radiated sound spectrum.

The acoustics of the bassoon has been the subject of relatively few studies compared with other woodwind instruments. One reason for this may lie in its complicated resonator geometry, which includes irregularly spaced toneholes with chimney heights ranging from 3 to 31 mm. The current article evaluates the effect of the open and closed tonehole lattice (THL) on the acoustic response of the bassoon resonator. It is shown that this response can be divided into three distinct frequency bands that are determined by the open and closed THL: below 500 Hz, 500-2200 Hz, and above 2200 Hz. The first is caused by the stopband of the open THL, where the low frequency effective length of the instrument is determined by the location of the first open tonehole. The second is due to the passband of the open THL, such that the modes are proportional to the total length of the resonator. The third is due to the closed THL, where part of the acoustical power is trapped within the resonator. It is proposed that these three frequency bands impact the radiated spectrum by introducing a formant in the vicinity of 500 Hz and suppressing radiation above 2200 Hz for most first register fingerings.