## 1pMU4. The measured vocal tract impedance for clarinet performance and its role in sound production.

### Session: Monday Afternoon & Evening, May 13

### Time: 2:45

**Author: Teresa D. Wilson**

**Location: School of Music, Box 353450, Univ. of Washington, Seattle, WA 98195**

**Abstract:**

The role of the vocal tract in clarinet performance has been investigated
by examining the vocal tract impedance, Z[inf u]. Theory predicts that Z[inf u]
peaks aligned with harmonics of the pitch frequency stabilize the oscillation.
The vocal tract impedance was measured directly with a one-microphone technique
and indirectly from a calculation using the continuity of flow equation p[inf
u]/Z[inf u]+p[inf d]/Z[inf d]=0, where p[inf u] and p[inf d] are the mouth and
mouthpiece pressures and Z[inf d] is the instrument impedance. The continuity
equation was verified for single tones and then used to examine the role of the
vocal tract in a variety of musical situations. In orchestral excerpts, the
performer tends to align resonances with the first and/or second harmonics, and
there is some dependence on the musical context. For multiphonics, the performer
creates a resonance that supports an oscillation at a linear combination of the
audible pitch frequencies. For tones played with pitchbend, induced by slacking
the jaw muscles, the playing frequency is controlled by the frequency of a
large-amplitude vocal tract resonance, for which |Z[inf u]|(approximately equal
to)100--400 CGS ohms. Z[inf u] changes only slightly when clarion tones are
played without the register key, suggesting that other variables are involved.

from ASA 131st Meeting, Indianapolis, May 1996