How the slentho makes its sound
In the Hornbostel–Sachs system, which classifies instruments by how they produce sound, the slentho belongs to the struck idiophones: the body is struck directly – bells, gongs, xylophones and cymbals.
More broadly it is one of the idiophones, where the solid body of the instrument itself vibrates, without strings or a stretched membrane.
Press play above and watch the spectrum: the evenly spaced peaks are harmonics, and their relative strength is what gives the instrument its character.
From Wikipedia
The slentho (also spelled slento) is a musical instrument of the gamelan. It is similar to the saron family of instruments, and would be its lowest member (pitched one octave below the saron demung). Like those instruments, it has (typically) seven keys in the same arrangement, over a resonator box, and is hit with a wooden mallet (tabuh). However, unlike the other sarons, the center of its keys have a boss similar to that of a bonang. The slentho usually has the same notes as the slenthem, but a brighter, louder sound.
The slentho is no longer a common instrument in the gamelan, having largely been replaced by the slenthem. It does, however, continue to be used in older sets of gamelan, in which it may be used in preference to the slenthem in gendhing bonang.
Other struck idiophones
Frequently asked questions
What does a slentho sound like?
As one of the struck idiophones, its sound comes from the way the body is struck directly.
What type of instrument is the slentho?
It is classified as struck idiophones (Hornbostel–Sachs 111.222).