NOTE: all the percussion sound samples were performed by Matteo Manzini on 04/12/2007. Sound engineer: Valerio Carboni.
Triangle
We have collected several sound samples of the triangle, partly to dispel the myth of the "Cinderella of instruments". The triangle is a fascinating instrument which, despite its elementary structure, produces a very rich and ever-changing sound.
The instrument seems elementary because, unlike other more complex ones, it does not "let you down": once struck, even by an inexperienced hand, it always produces a "ding", but the richness and variety of its effects certainly do not end there. Unfortunately, of all the vibration modes of the triangle, only the highest ones radiate efficiently enough to be heard at a distance; this is why most of the sound of the triangle is lost, and why it is used only as a "special effect" in a modern symphony orchestra. An effect, nevertheless, that can add a magical colour to the music.
In musical traditions far from ours, on the other hand, idiophones like this one take a large place at the centre of the stage, and not only at its margins.
Let us try to understand how the sound arises and what its main features are, remembering that the true richness of the sound can only be perceived at close range.
Anatomy of a "ding"
In this example the triangle is struck with a metal beater in five different positions (see the photograph at the top of the page):
halfway along the lower side
halfway along the left side
near the lower left corner
exactly on the lower left corner
near the top corner (the one by which the triangle is hung)
First of all, note that the triangle is considered an instrument of indefinite pitch, but for a completely different reason than, for example, the snare drum. The snare drum emits a broad-spectrum noise, from which a few distinct peaks barely emerge, mostly due to the resonances of the shell. The triangle, instead, as the sonogram clearly shows, emits a very distinct set of well-defined frequencies.
There are two reasons why its pitch is indefinite:
The partial components of the sound do not form a harmonic series
The intensities of the peaks change continuously, making the sound constantly shift. As first one peak and then another prevails, the apparent pitch of the instrument is in continuous motion.
waveform
sonogram
Audio
PC_TriangoloDiversiColpi.mp3
PC_TriangoloDiversiColpi
Learning to listen
waveform
sonogram
Audio
PC_TriangoloArmonici.mp3
PC_TriangoloArmonici
Effects
waveform
sonogram
Audio
PC_TriangoloRullo.mp3
PC_TriangoloRullo
waveform
sonogram
Audio
PC_TriangoloGira.mp3
PC_TriangoloGira
Tambourine
The tambourine (Basque drum) is a frame drum. Unlike the snare drum, it has a single membrane stretched over a cylindrical frame, so it has no resonating cavity. It is called a "jingle tambourine" when metal jingles are set crosswise into the frame, as in the picture. The tambourine typically has a rhythmic and timbral role. A single stroke produces sounds of different colour depending on how the membrane is struck with the hand (fingers, knuckles, palm).
waveform
sonogram
Audio
PC_TamburelloDiversiColpi.mp3
PC_TamburelloDiversiColpi
The jingles always add high-frequency components to the sound. "Roll" effects are obtained by sliding the fingers over the membrane very close to the frame. Because of the friction between fingers and membrane, the fingers do not slide but skip, producing a series of small excitations very close together in time. The same friction-based mechanism, when it occurs between chalk and blackboard, produces the characteristic, annoying squeak. In the violin, too, the bowed string moves "in jerks": here the same phenomenon is caused by the friction between the string and the hair of the bow. On the page on the physical and mathematical aspects of harmony you will also find some passages quoted from Galileo, who was able to exploit this phenomenon to deduce the relation between the frequency of a sound and its pitch.
waveform
sonogram
Audio
PC_TamburelloRulli.mp3
PC_TamburelloRulli
Castanets
Castanets are very ancient instruments, traces of which are found in Sumerian Mesopotamia. They spread in the West mainly through Spain. They come in two forms: the symmetric one shown here, in which two small circular plates of hardwood are shaped into small cups and struck against each other, and the asymmetric one, called "with handle", less spectacular but better suited to the orchestra, in which each cup strikes a wooden support to which it is attached and which serves as a handle.
waveform
sonogram
Audio
PC_Nacchere.mp3
PC_Nacchere
Woodblock
The woodblock is a block of wood into which a slit is carved. Its prehistoric version (a hollow log with a lengthwise crack) is perhaps the most elementary and ancient of the percussion idiophones. The modern (or Chinese) version, of small size, produces a particularly dry and penetrating sound when it is made of hardwood. Plastic versions like the one pictured are used for convenience, but produce a relatively softer sound.
waveform
sonogram
Audio
PC_Woodblock.mp3
PC_Woodblock
Check your understanding
The triangle and the snare drum are both instruments of indefinite pitch. For the same reason?Answer. No. The snare drum emits broadband noise, from which a few peaks barely emerge. The triangle instead emits well-defined frequencies, but they do not form a harmonic series and their intensities change continually: the apparent pitch moves from one peak to another.Why can much of the sound of the triangle be heard only close up?Answer. Because the triangle is a thin rod, much thinner than the wavelengths of its lowest modes: it moves very little air and radiates them poorly. At a distance mainly the higher modes arrive, which radiate more efficiently.Sliding the fingers along the edge of the tambourine's membrane produces a "roll". What do this effect, the violin bow and chalk squeaking on a blackboard have in common?Answer. The "jerky" motion produced by friction: the fingers (or the bow hair, or the chalk) stick to the surface until the elastic force makes them slip, then stick again. The cycle of sticking and slipping produces a series of small excitations very close together.
