Re: Brass instruments

[brian whatcott <inet@INTELLISYS.NET>]

At 15:02 7/8/99 -0700, Mel Bartels wrote:
...
> I have taught that the trumpet bell acts to reflect 90% of the
> standing wave energy back into the
> trumpet, the remaining 10% of the energy goes into the
> tone projected into the room.  This
> reflection point can be modified by the hand as french horn players do
resulting in a pitch change
> and also a slight tonal change. ...

 Mel Bartels

I wonder what support Mel has for this magnitude of discontinuity
 at the bell mouth?
It is a provocative thought. Recall the acoustic record players
- the 'gramophones'- with their big exponential horns.
    One supposes their acoustic impedance transformation ratio must
have been much larger than that of a brass instrument.
They needed to couple as much of the sound as possible to free air.

While it's fairly easy to recall a value for electrical impedance
of free space - I wonder what the acoustic impedance for free air is?



brian whatcott <inet@intellisys.net>
Altus OK