[ Reference Leonardo Forti in 187026 MMDigest ]

I have to take exception with Mr. Forti's statement that "If you don't
finger any valves, you can't play all the notes on a tuba.  You can
play only some notes -- those not requiring any fingering."  He is
correct with regard to the typical human musician but not with regard
to the computer played sousaphone.

The tuba produces nothing itself, it is only an amplifier.  Based on my
own experience as a trombonist for 50+ years, wind instruments such as
the tuba, baritone, trombone, trumpet, etc. produce a tone by the
player buzzing their lips to produce a vibrating column of air of the
correct frequency to correspond to the note to be played.  The purpose
of the instrument is to amplify that sound.

Different lengths of tubing produce different resonant frequencies and
the purpose of the valves on a tuba or trumpet, or the slide on a
trombone, is to alter the length of the tubing to produce different
notes. These variances in tubing are necessary to compensate for the
fact that most humans, even trained musicians are not capable of the
precise control required to produce a chromatic scale without some
variation in the resonance.

Most brass players are capable of "lipping" a note up or down,
sometimes by a half tone or even a full tone.  A good example of this
is a tenor trombone player managing the tones (b, c, c#, and d) between
a pedal b flat and the low e natural which I believe most can do, if
necessary.  A better example was Arthur Pryor.

Pryor learned to play on a battered old trombone given to his father in
settlement of a debt.  He became fairly proficient even though he only
used the slide in two positions.  Apparently it was difficult to move
the slide on the battered old horn.  Later, a traveling salesman told
him that if he oiled the slide, there were actually seven different
positions.  The skill he had developed served him well with all seven
positions.  Through the years he played many notes in "false" or
improvised positions which gave him a flexibility in performance that
brought him world wide acclaim.  See Windsong Press, Arthur Pryor,
http://www.windsongpress.com/brass%20players/trombone/Pryor.pdf 

Not unlike our current point of discussion, a European who heard Pryor
play said "No one can play that well, it is a Yankee trick."  See
Wikipedia, Arthur Pryor, https://en.wikipedia.org/wiki/Arthur_Pryor 

Unfortunately, virtuosos like Pryor are few and far between but he most
certainly was playing the instrument regardless of whether the correct
position was used.

The point of all this is that with a vibration source capable of
producing the _precise_ vibrating frequency at the mouthpiece, the
length of the tubing through which it is amplified becomes irrelevant,
and thus the valves depressed or position employed also becomes
irrelevant since they are simply altering the length of the tubing.
This is true whether it is an ordinary musician lipping the note up or
down, a virtuoso like Pryor, or a computer controlled membrane.

I have "played" the computer mouthpiece (provided the stable air source
for) with it attached to a conventional upright tuba, a brass sousaphone
and a fiberglass sousaphone.  While a note is sustained you can do
whatever you want with the valves, push them in or leave them alone and
the tone does not change.  That's because the computer mouthpiece is
producing the precise frequency required for that note.

Similarly, I have played it to produce a multiple note scale run
without fingering a valve.  In both cases, the tuba is amplifying the
vibrating column of air delivered to it at the mouthpiece.  The
computer is most certainly "playing" the tuba, and it is doing so
regardless of the valve positions.

Here is a short clip I recorded earlier this year of the sousaphone
playing along with the accordion and a 20er street organ:
https://www.youtube.com/watch?v=_pFhQgwujNw 

At around the 43-second mark, and again very close to the end, you can
hear the tuba play multiple descending notes and it is pretty clear the
valves aren't moving because I have one hand playing the accordion and
the other cranking the organ.

Deane Shepard