A brass instrument is a musical instrument that produces sound by sympathetic vibration of air in a tubular resonator in sympathy with the vibration of the player's lips. Brass instruments are also called labrosones, literally meaning "lip-vibrated instruments".

There are several factors involved in producing different pitches on a brass instrument: One is alteration of the player's lip tension (or "embouchure"), and another is air flow. Also, slides (or valves) are used to change the length of the tubing, thus changing the harmonic series presented by the instrument to the player.

The view of most scholars (see organology) is that the term "brass instrument" should be defined by the way the sound is made, as above, and not by whether the instrument is actually made of brass. Thus one finds brass instruments made of wood, like the alphorn, the cornett, the serpent and the didgeridoo, while some woodwind instruments are made of brass, like the saxophone.

Modern brass instruments generally come in one of two families:

Ingolf Dahl (June 9, 1912 – August 6, 1970) was a German-born American composer, pianist, conductor, and educator.

Born in Hamburg, Germany to a German father and a Swedish mother, his birth name was Walter Ingolf Marcus. He studied with Philipp Jarnach at the Hochschule für Musik Köln (1930–32). Leaving Germany where the Nazi Party was coming to power, he continued his studies at the University of Zürich with Volkmar Andreae and Walter Frey. Living with relatives and working at the Zurich Opera for more than six years, he rose from an internship to the rank of assistant conductor. He served as a vocal coach and chorus master for the world premieres of Alban Berg's Lulu and Paul Hindemith's Mathis der Maler.

After Switzerland became hostile to Jewish refugees and his role at the Opera was restricted to playing in the orchestra, Dahl emigrated to the United States in 1939. There he used the name Ingolf Dahl, based on his original middle name and his mother's maiden name. He consistently lied about his background, claiming to be of Swedish birth and denying his Jewish heritage. He claimed to have emigrated a year earlier than he actually had. He settled in Los Angeles and joined the community of expatriate musicians that included Ernst Krenek, Darius Milhaud, Arnold Schoenberg, Igor Stravinsky, and Ernst Toch. He had a varied musical career as a solo pianist, keyboard performer (piano and harpsichord), accompanist, conductor, coach, composer, and critic. He produced a performing translation of Schoenberg's Pierrot Lunaire in English and translated, either alone or with a collaborator, such works as Stravinsky's Poetics of Music. He performed many of Stravinsky's works and the composer was impressed enough to contract Dahl to create a two-piano version of his Danses concertantes and program notes for other works. In 1947, with Joseph Szigeti he produced a reconstruction of Bach's Violin Concerto in D Minor.