The History of Sound Waves

Before the discovery of the fact that sound traveled in waves, for years many people were bewildered and curious about how we were able to hear what we hear. This all changed when some of the most notable scientists discovered how sound travels.

Aristotle (384 BC- 322 BC)

Aristotle (384 BC- 322 BC)

One of the first people to claim that sound traveled in waves was Greek philosopher, Aristotle. Aristotle claimed that the quality of sound will be unchanged and will travel as far as the waves reaches.

 

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Gailileo Galilei (1564-1642)

Italian physicist, Galileo, was the first scientist to record the relationship between the frequency of the wave to the pitch it produces. Since the sound waves produced by musical instruments vary in pitch, this was a very significant discovery. He was able to come to this conclusion after taking a chisel and scraping it against a brass plate. From there, he began to observe that the pitch of the screech varied directly with the spacing of the grooves, which are created from the contact between the chisel and the brass plate.

 

Marin Mersenne (1588-1648)

Marin Mersenne (1588-1648)

Now that people knew that sound traveled through waves, people wanted to know how exactly fast these sound waves traveled. Marin Mersenne, French mathematician, was the first person to record the speed of sound as it travels through air in the year of 1640. As technology got better as time progressed, Mersenne’s speed of sound was shown to be an error of less than 10%. Although 10% might seem like a large error for this type of information, his findings are quite impressive considering the lack of technology during his time.

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Robert Boyle (1627-1691)

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Diagram of Boyle’s Experiment

 

 

 

 

 

 

 

 

 

 

 

20 years after Mersenne’s discovery, a British scientist, Robert Boyle, determined that in order for sound to travel/transfer, it has to go through a medium. This medium would be air. Boyle was able to come to this conclusion by conducting an experiment in which he placed a ringing bell inside a glass jar. From there, he observed that the ringing noise made by the bell cannot be heard. This is due to the air being pumped out of the jar. By having no air source, sound doesn’t have the capability to be produced; therefore, you are not able to hear anything.

 

Joseph Fourier (1768-1830)

Joseph Fourier (1768-1830)

Research on sound waves along with waves in general continued throughout the 1700s and 1800s. During this period, many scientists and mathematicians began to extensively study the topic due to the improvement of technology and knowledge from minor discoveries/experiments done by people before their time. This included the French Mathematician, Joseph Fourier, who discovered that the sound waves that are produced by a vibrating string are just series of waves that travel periodically.

Christian Doppler’s findings about the frequency of sound waves is argued to be the most significant out of all the different discoveries that other people had made about sound waves throughout history. The Austrian physicist is known for developing a mathematical equation that calculated the frequency of a wave when the waves of the source is moving relatively to the person/observer. He claimed that as the source of the waves moved further away from the observer, the frequency of the waves would become lower; therefore, the person would hear the sound with less intensity. On the other hand, if the the source of the waves moves closer to the observer, the person would hear the sound with greater intensity. This coined the term, ” The Doppler Effect.” Specifically for sound waves, Doppler came to the conclusion that the velocity of the waves produced are directly influenced by the medium in which it travels in.

Christian Doppler (1803-1853)

Christian Doppler (1803-1853)

 

Doppler's Frequency Equation

Doppler’s Frequency Equation

 

 

 

 

 

 

 

 

Relating specifically to music, a discovery made in the late 1890s by Harvard Physicist, Wallace Sabine, completely changed the setting in which musicians perform in. Before Sabine’s time, nobody paid attention to the venue that musicians played in. Sabine was assigned to renovate and improve the acoustics of a Harvard museum. In this process, Sabine became the first person to measure reverberation. From this, Sabine experimented with several things including the seats of the venue along with materials that absorb sound. Opened in 1900, the Boston Symphony Hall became the first building that incorporated scientific formulated acoustics in its construction. Today, concert halls, including ours, are built in close attention to acoustics, which wouldn’t have been done without the work of Sabine.

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Boston Symphony Hall (1900)