The sounds of music and speech are deeply rooted in man's evolutionary past. The study of sound began in ancient times. As early as the 500’s B.C., Pythagoras, a Greek philosopher and mathematician, conducted experiments on the sounds produced by vibrating strings. Pythagoras is said to have invented the sonometer, an instrument used to study musical sounds. This philosopher of Samos and Crotona, and his master, Thales of Miletus (ca. 640-546 B.C.), were the intellectual pioneers who introduced and established mathematics in the culture of ancient Greece. Pythagoras is primarily remembered now for his espousal of the science of numbers: this doctrine shaped nearly all inquiries about the nature of sound for the next few centuries.
Pythagoras was also one of the first to insist that precise definitions should form the cornerstone for logical proofs in geometry, although he is better remembered in this field for the unhistorical association of his name with the already well-known theorem about sums of the squares on the side of a right triangle. His teacher Thales, the first of the seven Wise Men of Greece had already brought deductive rigor to bear on geometry by introducing the concepts of logical proof for abstract propositions.
The most enduring contribution Pythagoras made to acoustical theory was to establish the inverse proportionality between pitch and the length of a vibrating string.
Aristotle (384 – 322 B.C.) probably deserves to be called the first mathematical physicist, since he was deeply concerned with the whole range of natural philosophy and with the use of mathematical reasoning as a tool for examining nature. The relative velocity of transmission of light and sound periodically commanded the attention of philosophers and scientist until nearly the middle of the eighteenth century. In referring to the physical nature of sound Aristotle wrote “lightning comes into existence after the collision and the [resulting] thunder, though we see it earlier because sight is quicker than hearing.” This inverted notion that thunder causes lightning persisted for centuries.7
Two other historians of antiquity expressed proper conclusions concerning the relative velocity of the transmission of light and sound. Pliny the Elder (A.D. 23-79) observed, “it is certain that when thunder and lightning occur simultaneously, the flash is seen before the thunderclap is heard (this is not surprising, as light travels more swiftly than sound).”
In about 400 B.C. Greek scholar Archytas (428 – 347 B.C.) expressed the fundamental idea that sound is always produced by the motion of one object striking another. This statement was paraphrased in one way or another and repeated by almost every writer of ancient and medieval times who considered the generation of sound. About 50 years later, the Greek philosopher Aristotle suggested that sound is carried to our ears by the movement of air. From then until about A.D. 1300, little scientific investigation took place in Europe, but scientists in the Middle East and India developed some new ideas about sound by studying music and working out systems of music theory.
European scientist began extensive experiments on the nature of sound during the early 1600’s. About that time, the Italian astronomer and physicist Galileo demonstrated that the frequency of sound waves determines pitch. Galileo scraped a chisel across a brass plate, producing a screech. He then related the spacing of the grooves made by the chisel to the pitch of the screech,
About 1640, Marin Mersenne, a French mathematician, obtained the first measurement of the speed of sound in air. About 20 yeas later, the Irish chemist and physicist Robert Boyle demonstrated that sound waves must travel in a medium. During the late 1600’s, the English scientist Sir Isaac Newton formulated an almost correct relationship between the speed of sound in a medium and the density and compressibility of the medium.
In the mid-1700’s, Daniel Bernoulli, a Swiss mathematician and physicist, explained that a string could vibrate at more than one frequency at the same time. In the early 1800’s, a French mathematician named Jean Baptiste Fourier developed a mathematical technique that could be used to breakdown complex sound waves into pure tones that make them up. During the 1860’s, Herman von Helmholtz, a German physicist, investigated the interference of sound waves, the productions of beats and the relationship of both to the ear’s perception of sound.8
Research Activity: Euclid of Alexandria (330-275 B.C.), Archimedes (ca. 287-212 B.C.), Galileo (1564-1642) and Plato (ca. 429-347 B.C.) are but a few of the great scientists of sound. Have student do research to get information on ancient scientist and modern day scientist who specialize in sound and acoustics.
