|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 C#4 and D4 , but raised in frequency. At higher frequencies, however, the situation is more complicated because of the cut-off frequency. The 1 kHz cutoff means that there are only three strong peaks, so only three notes that one can 'bugle' with this fingering. The first peak can be reduced in magnitude and shifted in frequency using a register hole (operated by the octave key). See D#5.
For general comments about the first register, see A#3. Compare with the impedance spectrum for a soprano sax on written D#4: 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 D#4.
For more explanation, see Introduction to saxophone acoustics.
You can hear D#4 played.