Vocal-Tract Influence during Saxophone Performance

Vocal-Tract Influence during Saxophone Performance

Gary P. Scavone, Antoine Lefebvre, and Andrey R. da Silva

Music Technology, Schulich School of Music
McGill University


Research in the Computational Acoustic Modeling Laboratory (CAML) with regard to measuring vocal-tract influence in saxophone performance has been ongoing since 2005.

A complete description of this work and the results are reported in:

Previous results were reported in 2006: This site is intended to provide further details on the measurement system.

Mouthpiece Setup

A stock alto saxophone mouthpiece, sold by Twigg Musique in Montreal, Canada, was fitted with two Endevco pressure transducers to measure the sound pressure inside the mouthpiece as well as inside the player's mouth. A groove was carved into the top of the mouthpiece to allow the 8507C-1 transducer to be positioned 3 mm behind the front edge of the mouthpiece tip. The 8510B-1 pressure transducer was threaded through the top of the mouthpiece about 5.5 centimeters from the mouthpiece tip to obtain internal pressure values.

Figures 1 and 2: The mouthpiece groove and the Endevco transducers (click to enlarge).

Figures 3 - 5: The complete mouthpiece system (click to enlarge).

Measurement System

The Endevco pressure transducers were connected to an Endevco 136 differential voltage amplifier and the signals from there were connected to a National Instruments (NI) PCI-4472 8-channel dynamic signal acquisition board (only four channels were used in this study). A small force sensing resistor (8 mm diameter) made by Interlink Electronics was placed under the cushion on the top of the saxophone mouthpiece to measure relative lip pressure. When the experiment was conducted, the external sound was recorded using a Sennheiser KE4-211-2 pressure capsule amplified by a Unides Design conditioning unit.

Figures 6 and 7: The mouthpiece and saxophone system with player (click to enlarge).

Figures 8 and 9: The mouthpiece and saxophone system in the IAC double-walled sound isolation booth (click to enlarge).

LabVIEW Interface

An NI LabVIEW virtual instrument was designed to allow realtime display of the spectra of the two pressure signals from the mouthpiece, as well as the lip and external pressures. When the "record" button is depressed in the interface (shown below), all four channels of data are also saved to a binary file in 8-byte floating-point format for subsequent analysis in Matlab.

Figure 10: The LabVIEW interface (click to enlarge).

Demonstration Video

The following video shows the measurements system and examples of its use while playing in the tradition and extended register of the alto saxophone, as well as special effects such as pitchbend, bugling, and multiphonics. The waveform in red is the internal mouthpiece pressure spectrum, while the waveform in white is the pressure spectrum inside the player's mouth.
© Gary P. Scavone. All Rights Reserved.
Computational Acoustic Modeling Lab (CAML)
Music Technology, McGill University.