Valve horns with narrow bore, with long air column (more than 2 m)
Valve horns with narrow bore, with short air column (less than 2 m)
The air itself is the vibrator in the primary sense. The standing waves are significantly confined within the instrument itself. The air-stream passes through the player's vibrating lips, so gaining intermittent access to the air column which is to be made to vibrate. The tubular body has a narrow bore profile that is intermediate between conical and cylindrical. The body can be lengthened or shortened by connecting or disconnecting auxiliary lengths of tube.
Valve horns with narrow bore
Hornbostel - Sachs
Valve horns