title: An active mute for the trombone.
abstract: A mute is a device that is placed in the bell of a brass instrument to alter its sound. However, when a straight mute is used with a brass instrument, the frequencies of its first impedance peaks are slightly modified, and a mistuned, extra impedance peak appears. This peak affects the instrument's playability, making some lower notes difficult or impossible to produce when playing at low dynamic levels. To understand and suppress this effect, an active mute with embedded microphone and speaker has been developed. A control loop with gain and phase shifting is used to control the damping and frequency of the extra impedance peak. The stability of the controlled system is studied and then the effect of the control on the input impedance and radiated sound of the trombone is investigated. It is shown that the playability problem results from a decrease in the input impedance magnitude at the playing frequency, caused by a trough located on the low frequency side of the extra impedance peak. When the extra impedance peak is suppressed, the playability of the note is restored. Meanwhile, when the extra impedance peak is moved in frequency, the playability problem position is shifted as well.
authors.affiliation: IRCAM, CNRS UMR 9912 STMS, 1 Place Igor-Stravinsky, 75004 Paris, France.
authors.forename: Thibaut
authors.initials: T
authors.lastname: Meurisse
authors.affiliation: IRCAM, CNRS UMR 9912 STMS, 1 Place Igor-Stravinsky, 75004 Paris, France.
authors.forename: Adrien
authors.initials: A
authors.lastname: Mamou-Mani
authors.affiliation: IRCAM, CNRS UMR 9912 STMS, 1 Place Igor-Stravinsky, 75004 Paris, France.
authors.forename: René
authors.initials: R
authors.lastname: Caussé
authors.affiliation: Ensemble Intercontemporain, 223 avenue Jean-Jaurès, 75019 Paris, France.
authors.forename: Benny
authors.initials: B
authors.lastname: Sluchin
authors.affiliation: The Open University, Walton Hall, Milton Keynes, MK7 6AA, United Kingdom.
authors.forename: David B
authors.initials: DB
authors.lastname: Sharp