The Clarinet

The clarinet consists of a closed cylindrical air column with a bell-shaped opening at one end. It's mouthpiece holds a single reed, in contrast to the double reed of the oboe family. It is typically constructed of wood. The traditional wood is an ebony from Africa, Asia or South America commonly referred to as grenadilla wood. Hard and black, this wood is capable of taking a high polish. The instrument most commonly used today is known as the B-flat clarinet; the next most common is the clarinet in A. The B-flat clarinet is about 60 cm (23.6 in) long and has a range of more than three octaves. Further details Sample waveforms

The Clarinet

The clarinet consists of a closed cylindrical air column with a bell-shaped opening at one end. It's mouthpiece holds a single reed, in contrast to the double reed of the oboe family. The reed is made from cane, and reeds from southern France are favored. The base of the reed is at least 3 mm thick and the reeds for the clarinets used in the U.S. are 69 mm long. The base width specification is 11.55 mm and the tip 13.05 mm. The body of the instrument is typically constructed of wood. The instrument most commonly used today is known as the B-flat clarinet; the next most common is the clarinet in A. The B-flat clarinet is about 60 cm (23.6 in) long and has a range of more than three octaves. There are also soprano clarinets (range D3 to F6) and bass clarinets some 94 cm in length which cover D2 to F5flat.

The clarinet is a versatile member of the orchestra, the principal treble woodwind of the concert band. The clarinet is a transposing instrument--its part in the score is written at a different pitch from the one actually sounded.

Since a closed air column does not produce even harmonics, the holes in the column must cover a wider range that those of the flute, carrying the instrument up to the third harmonic of the full column. The use of a register key can then cause the instrument to sound its third harmonic and contribute the notes of the higher register.

Register Key of Clarinet

The lower notes of the clarinet are achieved by opening holes along the closed cylindrical air column to shorten the air column and raise its fundamental frequency. A higher series of notes, called its "upper register" can be produced by forcing the air column to vibrate at its third harmonic frequency instead of the fundamental. This upper register is achieved by using a register key or "speaker key" which opens an additional hole in the side of the instrument close to the mouthpiece. This open hole destroys the fundamental mode and forces the air column up to its next resonance, which is the third harmonic (closed cylinders produce only odd harmonics). The open hole produces a pressure node at a point where the fundamental mode produces a significant pressure variation, so that the lowest vibrational mode cannot be sustained. The musical interval between the lower and upper registers is an octave plus a musical fifth, compared to an octave interval for overblowing the flute.

Register Key Action in Clarinet

When the register key is pressed, it opens a hole in the side of the instrument, producing a pressure node at that point. This destroys the fundamental mode and the frequency jumps to the third harmonic.

Clarinet Mouthpiece a Closed End?

It's obviously not closed, you're blowing air through it! Nevertheless, it acts acoustically as a closed end, so that the clarinet acts as a closed-end cylinder.

The action of the player's mouth on the reed causes the pressure oscillation to be greatest at the mouthpiece, a pressure antinode. Air rushing back and forth into the first open hole creates a motion antinode at that point which represents the other end of the oscillating air column. That in-and-out air motion alternately squeezes and expands the air in the column. The squeezing and expanding effect is greatest at the mouthpiece end, contributing to a large pressure variation there. The distance between a node and the closest antinode is a quarter wavelength, so the length of the vibrating air column of the clarinet represents a quarter wavelength for the fundamental frequency produced for this closed cylindrical column.