The illustrations were done with Corel Draw and the graph (spreadsheet) was done using Excel. There are just a few easy math equations involved in creating the data.

The wavelength (l) is the speed of sound (c) divided by the frequency (f).

The speed of sound in a warm moist instrument is usually represented by 347 m/s or 347,000 mm/s. Therefore the wavelength of A = 440 is: l = 347/440 = .7886 m or 788.6 mm.

A sound wave travels to the first open tonehole (or bell) and back to make a complete wave so the length of the instrument that sounds that note is always 1/2 the wavelength. Another way to say it is that the soundwave is 2L and the length of the saxophone is L.

For the note A Concert (F# on the alto sax) the length of the sound wave is 788.6 mm and the "sounding length" of the saxophone from the apex of the missing cone is 394.3 mm.

A great resource to learn more about saxophone acoustics is here:

http://www.phys.unsw.edu.au/~jw/saxacoustics.html
John