Page 47 - Fall 2005

Scanning the journals
􏰀 Theory predicts abundant production of acoustic waves in subsurface layers of the Sun, and such waves are believed by many to constitute the dominant heating mechanism of the chromosphere, according to a paper in the 16 June issue of Nature. Such waves are difficult to detect because of distur- bances in the Earth’s atmosphere. This paper reports the detec- tion of such waves and numerical simulations to show that the acoustic energy flux of these waves is too low, by a factor of at least ten, to balance the radiative losses in the solar chromos- phere. Acoustic waves therefore cannot constitute the dominant heating mechanisms of the solar chromosphere.
􏰀 There is widespread belief among players and listeners alike that violins improve with age and/or playing. Although mechanical measurements show noticeable differ- ences between two violins built from the same wood sam- ples, rankings of the instruments by experienced playing and listening panels showed no statistical differences in the finished instruments, according to a paper in the April issue of Acoustics Australia. One instrument had been played regularly and the other had been kept in museum condition. 􏰀 Tree frog embryos have a remarkable ability to sense and interpret vibrations, according to a paper in the July issue of Animal Behaviour. Eggs of the red-eyed tree frog usu- ally hatch after seven days, but the embryos can emerge up to 30% earlier to escape a predator’s attack. Upon hatching they drop into the water and, as tadpoles, swim away to safe- ty. They are more likely to hatch when exposed to vibrations recorded from a snake attack than when exposed to record- ings of heavy rain. The embryos must therefore be able to distinguish between these different kinds of motion.
􏰀 The Australian didgeridoo is a simple musical instru- ment that is capable of a spectacular variety of timbres, according to a brief paper in the 7 July issue of Nature. Simultaneous measurement of the didgeridoo sound and the acoustic impedance of the player’s vocal tract just inside the lips indicated that the maxima in the envelope of the sound spectrum are associated with minima in the impedance of the vocal tract. This acoustic effect is similar to the produc- tion of vowel sounds made during human speech or singing,
although the mechanism is different, and leads to the con- clusion that experienced players are subconsciously using their glottis to accentuate the instrument’s tonal variation. 􏰀 New evidence for bubble fusion or sonofusion is report- ed in the May issue of Nuclear Engineering and Design. Engineers at Purdue University used the same test chamber filled with deuterated acetone as in previous experiments (see Summer 2004 issue of ECHOES) but with californium- 252 as a continuous source of neturons instead of the pulsed source previously used. The acetone was exposed to the neutron source and then bombarded with ultrasound to pro- duce tiny bubbles that expand before imploding.
􏰀 The March issue of Acoustical Science and Technology is a special issue on Room Acoustics in honor of RADS 2004 (International Symposium on Room Acoustics: Design and Science 2004) held on the Island of Awaji in April 2004. The symposium, which was a satellite symposium of the International Congress on Acoustics (ICA 2004), included 20 invited oral presentations and 63 poster presentations, of which 12 papers, one technical report, and 12 acoustical letters appear in this special issue.
􏰀 A novel method of controlling reflections in a listening room, using flat panel loudspeakers, is described in a paper in the May issue of the Journal of the Audio Engineering Society. Models and implementations are presented for sin- gle-channel, two-channel, and five-channel arrangements. The results of a pilot listening test showed that differences in reflection patterns were readily detected by a panel of experienced listeners.
􏰀 EURASIP Journal on Applied Signal Processing, Volume 2005, Issue 9, is a special issue on Anthropomorphic Processing of Audio and Speech. Some papers are paid for by the authors and can be downloaded free of charge at http://www.hindawi.com.eg/asp/.
􏰀 The July/August issue of Acta Acustica/Acustica includes a two-part review article on “Noise and Its Effects—A Review on the Qualitative Aspects of Sound.” The first part deals with “Notions and Acoustic Ratings,” while the sec- ond part deals with “Noise and Annoyance.”
Thomas D. Rossing
ASA 2006 Meetings–Plan Now to Attend!
5–9 June • Providence, RI (Abstract submission deadline: 24 January 2006)
28 November–2 December • Honolulu, HI • 4th joint meeting–Acoustical Society of America and Acoustical Society of Japan (Abstract submission deadline: 30 June 2006)
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