The movies and sounds presented on this page are related to the article "Experimental study of the effects of the long chimney of a closed tonehole on the sound of bassoon" The Journal of the Acoustical Society of America 153, 1229 (2023). Link to the article
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A simple conical instrument, imitating a bassoon, is played with an artificial mouth whose control parameters are constant. The instrument has three closed lateral holes. Their length is simultaneously modified by means of a piston inserted in the chimney of the holes. More details are given in the article.
This spectrogram represents the evolution with respect to time of the absolute magnitude of each harmonic component of the sound radiated by the simple conical instrument. The x-axis indicates the lengths of the 3 chimneys which vary simultaneously from 0 mm to 100 mm and then from 100 mm to 0 mm.
The muffler effect of the chimney is clearly observable. A comb filter, corresponding to the series of "quarter-wave" resonances of the chimney, appears on the spectrum.
This spectrogram represents the evolution with respect to time of the absolute magnitude of each harmonic component of the pressure measured inside the double-reed for the simple conical instrument. The x-axis indicates the lengths of the 3 chimneys which vary simultaneously from 0 mm to 100 mm and then from 100 mm to 0 mm.
A variation in pitch can be heard. This is a logical consequence of the chimney length variation, but it is not related to the "quarter-wave" resonances. The distribution of the energy between the partials is also modified by the chimney length. For example, the "formants" in the range 1.5kHz-2.5kHz are shifted when the corresponding partials cross the quarter-wave resonance (in the range 40mm-70mm).
A French bassoon is played with an artificial mouth whose control parameters are constant. The fingering used is an alternative fingering for a C#, in which only 3 long long_chimneys are closed. Their length are modified by using piston inserted into the holes' chimney. The usual offset between the 3 chimneys (0mm, -3.5mm, 5mm) is maintained during the experiment. More details are given in the article.
This spectrogram represents the evolution with respect to the chimney length of the absolute magnitude of each harmonic component of the sound radiated by the simple conical instrument. The length of the chimney is varied by step of 10mm, and 1s of sound is recorded.
It is very difficult to perceive visually the muffler effect on this absolute spectrum, contrary to its relative variation presented in the article. Changes in the sound are however perceptible to the ear.
This spectrogram represents the evolution with respect to the chimney length of the absolute magnitude of each harmonic component of the pressure measured inside the double-reed of the bassoon. The length of the chimney is varied by step of 10mm, and 1s of signal is recorded.
Visually, the reed pressure spectrum appears to be independent of chimney length. A small variation can be heard, but it is difficult to relate it to the variation in chimney length. It may also be due to slight fluctuations in the parameters of the artificial mouthpiece.