General Monthly Meeting
An Afternoon of Science and Music
Special Joint Meeting with members of the
Powerhouse Museum Society
Date: Saturday 1st June, 2002
Venue: Target Theatre, Level 3, Powerhouse Museum
Time: 2.30 - 5.00pm
Musical Instruments and How They Work - Joe Wolfe
How is it that a few pieces of wood and metal can make such wonderful sounds?
The musician is a large part of the answer, or course, and we know that talent
and hard work are required. But how do the instruments themselves work? Why are
their sounds musical? What are their strengths and weaknesses and what do these
mean for composers and players? In this talk, Prof. Wolfe (who plays a number of
instruments himself) will start with demonstrations of the fundamental
principles, and then move on to explanations and demonstrations with real
instruments from the string and woodwind families.
Music, Physics and the Puzzle of Consonance - Ian Jonhston
Few people would disagree that as our science (particularly physics) progressed
from the earliest recorded times to what it is today, it has had great
influence on the way music developed. What is not so well known is that the
influence was two-way. Music, in its turn, has changed the way physics
developed.
Western science, and Western musical theory, are both taken to have begun with the school of Pythagoras around 500 BC. His discovery, that musical intervals correspond with ratios of small whole numbers, led to the conception that the natural world could be analyzed in mathematical terms and that the cosmos displayed an order that was musical in character. In the succeeding two and a half thousand years, this Music of the Spheres has underpinned our way of looking at the cosmos, right up to our current understanding of an expanding universe controlled by the laws of quantum mechanics and string theory. Running through all this is one recurring question, the so-called puzzle of consonance. Why do human beings respond to music and musical sounds the way they do? What is the nature of the aesthetic enjoyment which we derive from both music and mathematics? It is the attempts by musicians and scientists down the ages to apply new knowledge to answering these questions which gives this story its fascination, and which will be the subject of this talk.
Joe Wolfe researches the acoustics of musical instruments, the voice and the ear. He is also a minor composer, whose works are occasionally played by orchestra and chamber ensembles. His laboratory has industrial collaborations with Cochlear and with Australian instrument makers including Gilet Guitars, the Woodwind Group and Terry McGee. He has a BSc in physics, a BA in French and a PhD in applied maths. He has worked at Cornell University, CSIRO and the École Normale Supérieure. He is an Associate Professor in Physics at the University of New South Wales.
Ian Johnston spent his early years on a pineapple farm in southern Queensland, studied physics and mathematics and was appointed to a lecturing position at the University of Sydney in the late 1960s. He was there until he retired in 2000, except for two separate years in the USA and one in England at the Open University. His research work was in nuclear physics and astrophysics, and more recently in physics education. He has a strong teaching interest in musical acoustics, sings tenor with the Sydney Philharmonia Choirs and has made occasional broadcasts on Australian national radio on that and other subjects.
Report on the General Monthly Meeting
by David Craddock
The Society's June Meeting was a combined affair with the Members of the Power House Museum. Council Member Karina Kelly introduced the speakers, after presenting the attentive and large audience with a short history of the Royal Society of New South Wales. The speakers treated the audience to two fascinating presentations, which carefully interwove music and science.
Professor Joe Wolfe at first demonstrated wave motion with the aid of a long, coiled spring, which he plucked. Varying frequency and wavelengths were demonstrated by grasping the spring at several intermediate positions. Prof Wolfe then brought in to play his talents with a range of musical instruments. From the cello he showed how harmonics are produced, with finger placement along the instrument's strings. The transition of sound from string, through the bridge to the large amplifying "box" of the cello was his lead into the range of wind instruments.
He described first, the flute, as "a column of air with a silver box around it." A clarinet was shown to play sounds half an octave lower than the flute. This is due to one end being closed for the mouthpiece thus enabling the clarinet to double the length of its sound waves. An oboe was next to appear, described as containing an almost conical column of air. This instrument worked by way of very low rate of airflow, and high pressure. It is "breath-limited." A myth was shattered when the cor anglais was produced. This was a longer instrument than the oboe and thus produced lower sounds. It had been thought that the pleasant sounds from this instrument were due to the design of the open end, which in size was apparently equivalent to the human mouth. Prof. Wolfe played the instrument with and without the end piece attached, and there was no discernible difference! When the bassoon was demonstrated, the audience was able to witness the low frequency sounds, almost as "clicks".
It had been mentioned earlier that a frequency of about 30Hz was important for human hearing. Below that frequency, sounds are more like definite "clicks" whereas above that frequency, we hear them more as smooth music. In his field of research, Prof. Wolfe mentioned that some 60,000 possible finger positions had been identified for the flute and were mapped and available on a website for use by musicians. He went on to briefly note that scientists now understand how to stimulate nerves in the human head, and thus help the deaf hear melodies. When asked what music they could perceive, before cochlear implants were available, the answer was rap and country and western music!
Professor Ian Johnstone began the second part of the afternoon's presentation with a question: "why do human beings like music?" He described some of the influence that music has had on physics over the past 2,500 years, from Pythagoras and his identification of various sounds of the anvil when struck by different hammers to the mathematics of the pentatonic scale. The modern scale of seven notes was linked to early astronomy. What was observed in music, was also seen in the heavens (five planets, sun and moon). The Renaissance period re-introduced the 4 basic studies: geometry, astronomy, arithmetic and music. Kepler produced the three laws of planetary motion, and published the data both geometrically and as music! The link between music and physics was described through examples such as Galileo Galilei, Rameau and Heisenberg. Prof. Johnstone ended with modern "superstring" theory in which the "basic building blocks of the universe are vibrating strings." The audience appreciated both speakers' presentations and it was heartening to hear questions from young and old.