Page 13 - Summer 2021

FEATURED ARTICLE
“Put a Sock in It!” Mutes for Musical Horns
Murray Campbell, Joël Gilbert, and Arnold Myers
Introduction
“Take the A Train” was first recorded by Duke Ellington and his orchestra in January 1941 and rapidly became the signature tune of this famous swing band. The recording (which can be heard at bit.ly/3pr3g7e), features two solos improvised by trumpeter Ray Nance. In the first solo, which starts around 50 seconds into the recording, Nance conjures a thin, edgy sound quality from his instrument; in the second solo, beginning at 1 minute 50 seconds, the full brassy brilliance of the trumpet is unleashed. How was this remarkable transformation of timbre achieved?
The answer to this question is revealed in a 1962 filmed performance of “Take the A Train” by the Ellington band in which Ray Nance reprises his 1941 solos (available at bit.ly/3u82DD5). When he walks forward to take the first solo, a copper-colored object can be seen protruding from the bell of the trumpet, almost completely blocking the opening through which the sound is radiated. This obstruction, which Nance removes during a break by the full band before the start of his second solo, is an example of a mute (in this case, a “harmon mute”). Brass instru- ments come in many different shapes and sizes; some
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https://doi.org/10.1121/AT.2021.17.2.13
examples of common trumpet mutes are illustrated in Figure 1. The acoustical behavior of mutes for musical horns is the subject of this article.
Muting Musical Instruments
The curtailment of social interaction arising from the Covid-19 pandemic has resulted in an explosive growth in the use of conference software platforms such as Zoom. A large fraction of the population is now familiar with the “mute button,” which an online host can use to silence the contributions of other participants in a meet- ing. The mutes used on musical instruments such as the violin and the trumpet have a more subtle effect than the mute button; a musical mute is not usually designed to completely suppress the radiated sound but to modify its loudness and timbre. A typical mute on a stringed instrument is a mechanical device that can be clamped on the bridge, reducing the efficiency with which vibra- tional energy is transferred from the strings to the body of the instrument. The primary role of a brass instrument mute is as a partial reflector of acoustic waves, controlling the balance between the energy trapped in the internal air column and the energy radiated as sound.
The use of an outwardly tapering horn to increase the radiated power of a wind instrument has a long history. For at least three millennia, the shofar, a lip-excited ram’s horn, has been used in Jewish religious ceremonies, and the metal trumpets found in the tomb of the Egyptian Pharaoh Tutankhamun expand into conical terminations.
All the sound from one of these ancient instruments is radiated from the mouth of the horn, and the same is true of the trumpets, trombones, French horns, and tubas of the modern brass family. These instruments can therefore be muted very effectively by introducing modifications in the region of the horn mouth, usually described as the bell. This article surveys some of the inventive techniques that performers have developed to mute musical horns.
Figure 1. Examples of trumpet mutes. A: plunger mute. B: fiber straight mute. C: aluminum straight mute. D: cup mute. E: harmon mute.
Volume 17, issue 2 | Summer 2021 • Acoustics Today 13