|Other names||Baritone, Tenor Saxhorn (formerly named, possibly conjectural)|
(Valved aerophone sounded by lip movement)
The baritone horn is a low-pitched brass instrument. Baritone horn is a piston valve brass instrument with a predominantly cylindrical bore like the trumpet and uses a wide-rimmed cup mouthpiece like that of its peers the trombone and euphonium, for like the trombone and the euphonium, the baritone horn is pitched in B♭ one octave below the B♭ trumpet.
In the UK the baritone is frequently found in brass bands. The baritone horn in the United States is common in school and university bands, the baritones found in school inventories often being older models as the instrument over time appears to be yielding in popularity to the euphonium.
A person who plays a baritone horn is a baritone (horn) player or baritonist.
Construction and general characteristics 
The baritone, like the trombone and euphonium is a nine-foot brass tube. Valves are most often piston-style. It is predominately of cylindrical bore, in contrast to the more conical bore of the euphonium, rendering its attack more distinct than the rounder attack of the euphonium.
The baritone is pitched in concert B♭ meaning that when no valves are in use the instrument will produce partials of the B♭ harmonic series. Music for the baritone horn can be written in either the bass clef or the treble clef. When reading from the bass clef, the baritone horn is a non-transposing instrument. However, when written in the treble clef it is often used as transposing instrument, transposing downwards a major ninth, so that written middle C for the baritone is concert B♭ below low C, with the fingerings thus matching those of the trumpet but sounding an octave lower. It is often used to play parts written for the similarly pitched tenor trombone or euphonium.
The baritone is part of the low brass section of the band. Its second partial with no valves pressed is concert B♭ on the second line from the bottom of the bass clef. The eighth partial with no valves pressed is concert B♭ in the center of the treble clef. Experienced amateur players can often reach a fifth above that to the concert F at the top of the treble clef, with higher notes reachable by the virtuoso.
The slightly erroneous diagram at the right shows the range ascending from the first partial with all valves pressed, i.e., the lowest fundamental available being concert third low F. In reality, the lowest B♭ baritone fundamental with all valves pressed is concert third low E, a semitone below the note shown in the diagram.
The baritone sounds with a timbre between the brightness of the trombone and the more mellow tone of the euphonium.
Distinguishing the Baritone Horn from the Euphonium 
Much more has been written about distinguishing the baritone horn from the euphonium than ever needed to be written as the similarities of the two instruments overwhelmingly outweigh the differences in bore and conicality/cylindricity.
Although both baritone horn and euphonium produce partials of the B♭ harmonic series in the same range, and both have a nine-foot-long main tube, the instrument identified as the baritone horn tends to have a smaller and more cylindrical bore than the euphonium, which latter is larger and exhibits a more conical bore. The baritone horn usually has a tighter wrap and a smaller bell, and is thus smaller and lighter overall, and produces a "lighter" sound versus the more solid, brassy timbre of the euphonium.
There is some confusion of nomenclature in the United States due to the old practice of American euphonium manufacturers calling their professional models by their proper names, and branding entry-level student models as baritones. This practice has nearly stopped. True baritone horns are sometimes called "British-bore Baritones" in the US to avoid this confusion.
Another common misconception is that the three-valve instrument is a baritone and that the four-valve instrument is a euphonium. Euphoniums often have a fourth valve as an alternate fingering for 1&3 split fingering with improved intonation. The fourth valve can also be viewed in the same way as an F trigger on trombone, repitching the instrument to expand the lower range. The fourth valve is less common to nearly nonexistent on baritones, but absence of a fourth valve is not a defining characteristic.
An "American baritone", featuring three valves on the front of the instrument and a curved forward-pointing bell, was common in American school bands throughout most of the twentieth century. While this instrument is in reality a conical-cylindrical bore hybrid, neither truly euphonium nor baritone, it was almost universally labeled a "baritone" by both band directors and composers.
Marching Baritone Horn 
Specially wrapped versions of the baritone horn have been created for use in marching bands and Drum and Bugle Corps. They have 3 valves and a front-facing bell and are the tenor voice of a drum and bugle corps, below the soprano voice of the trumpet, the alto voice of alto horn or mellophone, and above the low contrabass bugles or tubas.
Over the past several decades, the baritone advanced in the drum and bugle corps due to certain rule changes. Up until 1977, baritone bugles, as with all bugles at the time, were restricted to one horizontal piston valve and one rotary valve. That year, the Drum Corps International rules congress passed a rule allowing 2 vertical piston valves. The rules were amended once more in 1989 permitting the addition of a third valve. From the 1950s until 2000, all drum and bugle corps were required to use instruments pitched in the key of G. That year, Drum Corps International changed its rules again, allowing instruments in any key, with most other major organizations (e.g. Drum Corps Associates) following suit soon after. Since this change, the standard baritone has been the instrument pitched in B♭.
Some high school and college bands do not use marching baritones and continue to use upright-bell front baritone horns on the field.
Some marching bands substitute a section of baritones for the trombone or euphonium section.
The baritone horn has largely receded into the background in the concert band world of today. Notable artists who are today referenced as great baritone horn and/or euphonium players include Mel Sykes, Simone Mantia, and Leonard Falcone. The Leonard Falcone International Tuba and Euphonium Festival is a notable venue for aspiring artists on euphonium, but its namesake played baritone horn on his many recordings. Legendary trumpeter Maynard Ferguson used a baritone horn in the song "Gospel John" and in one of his three solos (the other two involving a valved trombone and a trumpet) in a live performance of one of his songs "Great Guns".
- Virginia Tech Multimedia Music Dictionary : Baritone Horn
- Robert Donington, "The Instruments of Music", (pp113 ffThe Family of Bugles) 2nd ED., Methuen London 1962
- Apel, Willi (1969), Harvard Dictionary of Music, Cambridge:: Belknap Press of Harvard University Press, 1972., pp. 105–110
- "What is a baritone Horn?". Wise GEEK. Retrieved 2012-05-26.
- Michigan State University Archives - Leonard Falcone Collection https://www.msu.edu/unit/msuarhc/falcone1.htm
- http://www.dwerden.com/emg/ Retrieved on 29 January 2008