• Volume/Page
  • Keyword
  • DOI
  • Citation
  • Advanced
   
 
 
 

Proceedings of Meetings on Acoustics

BROWSE VOLUMES

Year Range: 
Search Volume | RSS Feeds RSS
POMA - 163rd Meeting Acoustical Society of America/ACOUSTCS 2012 HONG KONG
Conference Location: Hong Kong Conference Date: 13 - 18 May 2012
Return to All Sections
back to top
RSS Feeds
FREE

Bamboo pipe wall vibrations in Asian free reed instruments

Miles Faaborg and James Cottingham

POMA Volume 15, pp. 035001 (June 2012); (7 pages)

Online Publication Date: June 22, 2012

Full Text: | Download PDF

Show Abstract
Asian free reed instruments generally employ bamboo pipes, and the properties of bamboo are of current interest, especially in relation to pipe wall vibrations. Recent results on measured physical properties of bamboo as used in Asian free reed instruments are presented, including mechanical properties of bamboo reeds as well as pipes. Recent investigations have been made of wall vibrations in the bamboo pipes of free-reed mouth organs for mechanically excited pipes. Modal frequencies and mode shapes of a number of pipes were measured, and measurements of pipe input impedance were made, some of which suggested possible changes occurring as a result of damping the pipe vibrations. The most recent work involves the study of pipe wall vibrations for a mechanically blown reed-pipe combination for undamped pipes and pipes heavily damped with sand or other damping material. Measurements were made of the internal and external sound fields as well as measurements of the wall vibrations.
Show PACS
43.75.Lm Free reed instruments
FREE

Real-time segmentation of the temporal evolution of musical sounds

John Glover, Victor Lazzarini, and Joseph Timoney

POMA Volume 15, pp. 035002 (August 2012); (8 pages)

Online Publication Date: August 03, 2012

Full Text: | Download PDF

Show Abstract
Since the studies of Helmholtz, it has been known that the temporal evolution of musical sounds plays an important role in our perception of timbre. The accurate temporal segmentation of musical sounds into regions with distinct characteristics is therefore of interest to researchers in the field of timbre perception as well as to those working with different forms of sound modelling and manipulation. Following recent work by Hajda (1996), Peeters (2004) and Caetano et al (2010), this paper presents a new method for the automatic segmentation of the temporal evolution of isolated musical sounds in real-time. We define attack, sustain and release segments using cues from a combination of the amplitude envelope, the spectro- temporal evolution and a measurement of the stability of the sound that is derived from the onset detection function. We conclude with an evaluation of the method.
Show PACS
43.75.Zz Analysis, synthesis, and processing of musical sounds
FREE

Performance expression synthesis for bowed-string instruments using ``Expression Mark Functions'

Yuma Koizumi and Katunobu ITOU

POMA Volume 15, pp. 035003 (November 2012); (8 pages)

Online Publication Date: November 02, 2012

Full Text: | Download PDF

Show Abstract
This paper proposes a method to synthesize the performance expression of bowed-string instruments using transfer functions for expression marks. ``Expression mark functions' are estimated from recorded performance sounds using string motion spectra and filtering the instruments' resonance properties. Bowed-string motion forms a triangular wave called the Helmholtz motion and can be determined from the bowed-string position. Deviations in waveform of expression performance are estimated by non-negative matrix factorization. The resonance properties of instruments are measured as time-stretched-pulse responses using a ``direct-drive speaker.' Expression mark functions are extracted by decomposing the actual performance sound using these data. To evaluate the synthesized sound quality, it is compared using expression mark functions and wavetable synthesis method. For all expression marks, almost all audience members could recognize changes in tone. MOS for ``dolce' and ``marcato' were scored 4.0.
Show PACS
43.75.De Bowed stringed instruments
43.75.St Musical performance, training, and analysis
43.75.Yy Instrumentation and measurement methods for musical acoustics
43.75.Zz Analysis, synthesis, and processing of musical sounds
FREE

Acoustic radiation from the pipa and yueqin

Christopher Waltham, Evert Koster, Andrzej Kotlicki, James Simard, and Nathan Wolfe

POMA Volume 15, pp. 035004 (March 2013); (6 pages)

Online Publication Date: March 27, 2013

Full Text: | Download PDF

Show Abstract
The pipa and yueqin are Chinese plucked string instruments. The examples studied here have soundboards made of Paulownia wood and each has a small cm-sized tone hole. The acoustic radiation patterns of these instruments have been measured as a function of angle and frequency. The measurements were made in an anechoic chamber and were obtained using an automated impact hammer. The radiation data are compared with measured vibration modes of the soundboxes. The spectra have maxima at higher frequencies than are typical for Western instruments (500 Hz for the yueqin and 700 Hz for the pipa, compared to 100 Hz for the guitar), whose construction tends to emphasize the fundamental frequencies of the strings. The Helmholtz resonances of the pipa and yueqin have also been observed, but the effect of the tone holes have not been detected in the radiation data and their function is not understood.
Show PACS
43.40.Ey Vibrations of shells
43.75.Gh Plucked string instruments
43.75.Yy Instrumentation and measurement methods for musical acoustics
Return to All Sections
Close

Home Publications Meetings Contact ASA Site Map Back to Top

Copyright © Acoustical Society of America

close