|Acoustics of the saxophone
Bb tenor saxophone
Notes are the written pitch.
At frequencies below about 1 kHz, this curve looks rather like that for D4 and D#4, but raised in frequency. At higher frequencies, however, the situation is complicated by the cut-off frequency. Here, the 1 kHz cutoff is also weakening the third peak. The first peak can be reduced in magnitude and shifted in frequency using a register hole (operated by the octave key). See E5.
This note is, acoustically at least, a cross fingering: there is a key closed below the first open key, as the schematic inset shows. Because of the large size of the tone holes, cross fingerings have little effect at low frequency.
For general comments about the first register, see A#3. Compare with the impedance spectrum for a soprano sax on written E4: same fingering but sounding one octave higher.
In the sound spectra for the low notes, we can notice a sudden increase in the negative slope of the spectral envelope that occurs close to the cut-off frequency of about 800 Hz. For general comments about the sound spectra of the first register, see A#3, which is the first note of that register.
Sound spectrum of a Bb tenor saxophone played using fingering for E4.
For more explanation, see Introduction to saxophone acoustics.
You can hear E4 played.