The octophone is a stringed musical instrument related to the mandola family

Mandola

The mandola or tenor mandola is a fretted, stringed musical instrument. It is to the mandolin what the viola is to the violin: the four double courses of strings tuned in fifths to the same pitches as the viola , a fifth lower than a mandolin...

 resembling an octave mandolin

Octave mandolin

The octave mandolin is a fretted string instrument with four pairs of strings tuned in 5ths, G, D, A, E , an octave below a mandolin. It has a 20 to 23 inch scale length and its construction is similar to other instruments in the mandolin family...

. It gained fame as a novelty instrument in the 1930s being declared as "eight instruments in one".

Tuning

The tuning is done with the machine head

Machine head

A machine head is part of a string instrument ranging from guitars to double basses, a geared apparatus for applying tension and thereby tuning a string, usually located at the headstock. A headstock has several machine heads, one per string...

s located on the headstock, much like other stringed instruments, and the strings are paired like the mandolin

Mandolin

A mandolin is a musical instrument in the lute family . It descends from the mandore, a soprano member of the lute family. The mandolin soundboard comes in many shapes—but generally round or teardrop-shaped, sometimes with scrolls or other projections. A mandolin may have f-holes, or a single...

 and 12-string guitar.

Common tunings include:

• Standard, G d a e'
• Chicago, d g b e'
• "Guitar", d'/d g'/g b/b e'/e'
• Alto mando, c g d' a'

Perfume organ

An unrelated instrument, also called "octophone" was an instrument invented by a French chemist, in which the keys of a keyboard activated one of 46 perfume fragrances.