4.3 Bore Profiles of Brass Instruments
127
Fig. 4.21 (a) Photograph of four brass instruments. Left to right: Kaiserbaryton, Wagner tuba,
bass trombone, tenor trombone. (b) Bore profiles of Kaiserbaryton (green), Wagner tuba (blue),
bass trombone (red), tenor trombone (black) (Color figure online)
then expand more and more rapidly towards the bell; the french horn starts with a
conical section, then becomes cylindrical and ends in a flaring bell almost identical
to the bass trombone in the region plotted.
The nature of the bore profile is clearly determined to some extent by the
practical way in which the instrument operates. On the ophicleide, side holes are
opened to shorten the effective sounding length, and the rapidly expanding bore
makes it possible to have large holes which radiate low frequencies more efficiently
(see Sect. 4.4). On the trombone, the use of a long slide makes it essential that a
substantial fraction of the tube length is of constant diameter. On the french horn,
the cylindrical part corresponds to the valve section in which alternative lengths of
tubing are switched in or out of the main bore: in this case a large section is switched
out to raise the playing pitch from F to B .
127
Fig. 4.21 (a) Photograph of four brass instruments. Left to right: Kaiserbaryton, Wagner tuba,
bass trombone, tenor trombone. (b) Bore profiles of Kaiserbaryton (green), Wagner tuba (blue),
bass trombone (red), tenor trombone (black) (Color figure online)
then expand more and more rapidly towards the bell; the french horn starts with a
conical section, then becomes cylindrical and ends in a flaring bell almost identical
to the bass trombone in the region plotted.
The nature of the bore profile is clearly determined to some extent by the
practical way in which the instrument operates. On the ophicleide, side holes are
opened to shorten the effective sounding length, and the rapidly expanding bore
makes it possible to have large holes which radiate low frequencies more efficiently
(see Sect. 4.4). On the trombone, the use of a long slide makes it essential that a
substantial fraction of the tube length is of constant diameter. On the french horn,
the cylindrical part corresponds to the valve section in which alternative lengths of
tubing are switched in or out of the main bore: in this case a large section is switched
out to raise the playing pitch from F to B .