alto trombone

The alto trombone has primarily been used in choral, orchestral and operatic settings, and came to some prominence in the early 19th century, particularly in the symphonies of Schubert, Schumann, Brahms and Mendelssohn. Since the 18th century in Vienna, it has also enjoyed a history as a solo instrument.

ˈträm-ˌbōn. : a brass instrument consisting of a long cylindrical metal tube with two turns and having a movable slide or valves for varying the tone and a usual range one octave lower than that of the trumpet.

And other brass instruments such as horns trumpets were improved by adding valves to them so this little fellow largely fell out of favor. And sort of come back a little bit into popularity.

Eb Pitched in the key of Eb, the alto trombone is not as common as tenor or bass but is still used in a variety of musical settings.

As the name would suggest, alto trombones play higher notes than tenor or bass models. To accomplish this, their bodies, bells and bores are smaller. And because they (and their slides) are shorter, the slide positions used to make notes are also different from other types of trombones.

An Alto Trombone is the smallest common trombone, these first started out in the 16th through to the 18th Century as the highest voice in the trombone section. Pitched in Eb (fourth higher) than the standard tenor trombone, this instrument has made a revival recently especially in the education sector.

The most common type of trombone is the tenor - so much so that it's considered the “standard” trombone.

The trombone is a 15th-century development of the trumpet and, until approximately 1700, was known as the sackbut. Like a trumpet, it has a cylindrical bore flared to a bell. Its mouthpiece is larger, however, suited to its deeper musical register, and is parabolic in cross section, like a cornet.

Nowadays, the word “alto” is a general term used to describe a lower female voice rather than a specific vocal category. Chorus music usually calls for an “alto” part for voices with a strong middle and lower register, but there's no real separate alto voice type in Western music.

alto, (Italian: “high”), in vocal music the register approximately between the F below middle C to the second D above - the second highest part in four-part music. The word alto originally referred to the highest male voice, singing falsetto (see countertenor).

Overall size: 818mm, bell diameter: 142mm. Sounding length: 2008mm. Bore: c 50mm from mouthpiece receiver: 11.3mm not expanding in 110mm from mouthpiece receiver; main tuning slide: descending slide, 11.3mm; ascending slide, 11.3mm; joint, 11.3mm.

Short answer - trombone is NOT a transposing instrument.