Instrument families

Every instrument makes sound the same way: something in it vibrates. What that something is, a string, a column of air or a surface that is struck, is the simplest way to sort instruments into families, and it is the way the books do it (Lacerda 1966, ch. XLII).

• In a string instrument, a string vibrates. The violin is the example.
• In a wind instrument, the air blown into a tube vibrates. The flute.
• In a percussion instrument, a surface vibrates after being struck. The drum.

Each family then splits into smaller groups, and the way it splits says something about how the instrument is played.

Strings: bowed, plucked, struck

A string can be set vibrating in three ways, and Lacerda divides the family accordingly (Lacerda 1966, ch. XLII).

Group	How the string vibrates	Examples
bowed strings	rubbed with a bow	violin, viola, cello, double bass
plucked strings	plucked by the fingers or a pick	harp, guitar, cavaquinho, viola caipira, lute
struck strings	hit by hammers	piano

The bowed strings form a family within the family, from highest to lowest: violin, viola, cello and double bass. They are the core of the orchestra.

The piano surprises people here. It has keys like an organ and is often grouped with percussion because its hammers strike, but what sounds is a stretched string. By how the sound is made, it is a string instrument (Lacerda 1966, ch. XLII).

A bowed string can also be plucked. A score asks for that with pizzicato, and for the bow again with arco; a player can also put on a mute to soften the tone. Blatter notes that this is how most changes of colour are written: there are few signs for timbre, so a score names the instrument and a handful of ways of playing it (Blatter 2007, part 1, art. 7).

Winds: woodwind and brass

Wind instruments are traditionally divided by material (Lacerda 1966, ch. XLII):

Group	Examples
woodwinds	piccolo, flute, oboe, cor anglais, clarinet, bassoon, saxophone
brass	trumpet, cornet, horn, trombone, tuba, euphonium

The names are older than the instruments. A modern flute is made of metal and the saxophone was always brass, yet both are woodwinds, by tradition (Lacerda 1966, ch. XLII). What really separates the two groups is how the air starts vibrating. In the woodwinds, the player's breath crosses an edge, as in the flute, or sets a reed vibrating, as in the clarinet and the oboe. In the brass, the player's lips buzz against a cup-shaped mouthpiece. Lacerda mentions this more scientific division, by mouth, reed and mouthpiece, and sets it aside as more than an elementary book needs (Lacerda 1966, ch. XLII).

The organ is a wind instrument too: its keys send air into pipes. Lacerda points out what makes it unusual among winds: it can sound many notes at once, where a flute or a trumpet plays one at a time (Lacerda 1966, ch. XLII).

Percussion: pitched and unpitched

Percussion divides by what is struck (Lacerda 1966, ch. XLII):

• stretched membranes: timpani, bass drum, snare drum, pandeiro, tamborim;
• hard bodies of wood or metal: xylophone, marimba, celesta, triangle, cymbals, gong, castanets, agogô, reco-reco.

The more useful split for a musician cuts across that one: some percussion instruments play definite notes and others do not. Among the membranes, only the timpani are tuned to a pitch; the other drums give sounds of indefinite pitch. Among the hard bodies, the xylophone, marimba and celesta play melodies, while the triangle, cymbals and gong do not (Lacerda 1966, ch. XLII). This is the difference between musical sound and noise, seen family by family.

Timpani are tuned before the piece starts, usually to the notes the harmony leans on most. The orchestral score Lacerda reproduces has them on C and G, the tonic and the dominant (Lacerda 1966, ch. XLII):

Hear the passage

Lacerda also lists instruments typical of Brazil, the agogô, reco-reco, chocalho and cuíca (Lacerda 1966, ch. XLII), and a samba ensemble is almost all of them at once.

Families in an orchestra

When instruments of one kind play together, they form a section, naipe in Portuguese: the strings, the woodwinds, the brass. Scores and orchestral players often use the Italian names, archi for strings, strumentini for woodwinds and ottoni for brass (Med 1996, ch. XXXVII). How those sections are grouped into ensembles, from a duo to a symphony orchestra, is a subject of its own.

What comes next

Every family covers a span of notes, and every instrument in it covers only part of that span. The double bass and the violin are both bowed strings, yet the bass reaches more than two octaves below the violin's lowest string. The span each instrument covers is its range, and putting instruments with different ranges and colours together is what ensembles are made of.