Although the glockenspiel player could hold two mallets in each hand the main playing technique is the performance of one-part melody lines, similar to the xylophone. Chords and harmony are nowadays more the province of the marimba. The vibraphone, on the other hand, is equally well suited to the playing of both melody and harmony.
In the orchestra, the main task of the glockenspiel is to add brightness to melody lines played by other instruments by doubling either in unison or one, two or three octaves above. It performs this task most frequently in combination with the flute, piccolo, celesta and harp, less often with the violin, oboe and clarinet.
Solos are fairly rare, though very effective and noticeable. They appear less for tonal reasons than for symbolic ones (the glockenspiel represents birds, or the swift passage of time).
The glockenspiel, as both a doubling and a solo instrument, can be seen as having an accentuating effect. In Classical-Romantic tradition it was used only sparingly so that its extremely bright timbre did not tire the audience. With the shift of the sound ideal in the 20th century the glockenspiel has been entrusted with a much greater range of tasks in a wide variety of musical styles.
A comparison between four mallet instruments
The glockenspiel is one of the melody instruments in the percussion group. This is true of all the other mallet instruments (vibraphone, xylophone, marimba, lithophone) as well. The tasks performed by the mallet instruments in the orchestra are determined by their sound characteristics and are consequently many and varied:
The extremely bright and high sound adds brilliance to melody lines and doubles them an octave higher. Thanks to the increased brightness provided by the glockenspiel, the melody line becomes more prominent. In smaller ensembles, the glockenspiel also performs solo tasks.
Mellow sound, great resonance. Used to prolong notes or chords. In the lower register it tends to be drowned by other instruments, in the middle and upper registers it can assert itself better. Inaudible in tutti passages. Performs both harmonic and solo tasks, especially in smaller ensembles.
Thanks to the short and very high-pitched sound of the xylophone, note sequences become more sharply defined and can be distinguished even in an orchestra tutti. The sound of the xylophone is audible in every combination of instruments. The xylophone’s specialty in the orchestra is the precise definition of immediately recognizable contours and not the blending in with other sounds.
Unlike the xylophone, the mellow, warm and gentle sound of the marimba is very well suited for tonal blends with other instruments. It performs chiefly harmonic tasks, in keeping with its low register. Its ability to assert itself is limited.