All About Sound, Vol. 2: Scientists and Inventors Quiz

Answer: Galileo Galilei

Galileo's interest in sound was likely inspired by his father, who was a mathematician, musician, and composer, and wrote texts about sound himself. Galileo utilized the sophisticated tools available at the time including chisels, knives, and brass plates to produce different pitches of sound.

He asserted that the pitch correlates with the number of vibrations. He is, therefore, credited with being one of the first to understand that the pitch of a sound is related to the frequency of vibration of an object.

Answer: Marin Mersenne

Marin Mersenne (1588-1648) was a French ordained priest. He developed Mersenne's laws which describe the harmonics of a vibrating strings such as those on string instruments. His seminal work, "Harmonie universelle," described all the musical knowledge available to him. For these works, he is called the "father of acoustics."

Answer: A sound recording device

Kircher is credited with being the first to experiment with a bell in a vacuum jar. This experiment eventually showed that sound is transmitted as waves in air rather than the alternative view of sound being carried by invisible particles produced by the source of the sound. He constructed the first known modern Aeolian harp, a stringed instrument played by the wind that was popular in the late 18th through the 19th century. Furthermore, he made the earliest known attempt to amplify sound with a parabolic horn that could be used either as a hearing aid or as a voice amplifier.

Sound recording devices were not made until the mid 1800s.

Answer: Measuring the time for an echo to reach him from clapping his hands

Newton indeed attempted to measure the speed of sound by clapping and timing the echo. He was the first to publish estimates of the speed of sound around 1686. Of course the difficulty at the time was getting a reasonably accurate measurement of the time it took for the echo to reach him. One method he employed was to use a pendulum which he adjusted to swing in the same period as the echo. Then, knowing the length of the pendulum, he could calculate the time.

Other early attempts to measure the speed of sound utilized the delay in sound vs. light from a gun or cannon fire at a distance. Marin Mersenne utilized this method as well as echoes to estimate the speed of sound even earlier than Newton.

Measurements can also be done using a source of sound with a known frequency and a tube which resonates at the same frequency as the source (the effective tube length can be adjusted such as by adding or subtracting water). Speed can be calculated from the frequency and wavelength (from the effective length of the tube). In 1866, physicist August Kundt invented a much more accurate way of measuring the speed of sound with this method and his device is referred to as Kundt's tube.

Accurately measuring the delay in sound vs. light from a lightning strike is more difficult because lightning is unpredictable and not repeatable.

Answer: Adding fluid to a bottle lowers the resonant pitch

The Helmholtz resonator is named for the physicist Hermann von Helmholtz who described resonators in his book in 1862. Resonance, which is the natural strongest vibrational frequency of an object, occurs in a resonator when air is forced into the cavity. This causes the air going in and out to vibrate at a specific frequency related to the dimensions of the resonator (and potentially other variables). The air going in reaches a point at which the pressure of the air inside the resonator exceeds the pressure of the air going in. The higher pressure inside pushes some air out. Once some air has gone out, the pressure going in again exceeds the pressure going out. This dynamic continues back and forth causing vibrations analogous to a spring going back and forth. A longer neck and larger volume of the resonator lowers the pitch of the resonant frequency and vice versa.

In addition to blowing into a resonator, providing sound at the resonant frequency also stimulates a resonator that has a second, no-neck opening, to resonate. For complex sounds, this type of resonator can detect whether or not a particular frequency is included in the sound since it will resonate when that frequency is present. Helmholtz produced sets of this type of resonator tuned to different frequencies which enabled early acoustic spectral analysis.

Exhaust resonators are used to reduce engine noise. The dimensions are calculated so that the sound waves reflected by the resonator help cancel out certain frequencies of sound in the exhaust before it enters the muffler.

Answer: Tin foil

Edison's early phonographs used a thin sheet of metal, usually tinfoil, as the recording material. The foil was temporarily wrapped around a helically grooved cylinder which was rotated for recording and playback. Sound was encoded as the depth of the groove made into the foil. Instead of tinfoil, Alexander Graham Bell and associates utilized wax cylinders for recording and received a patent in 1886.

Emile Berliner first experimented with celluloid as a recording material, but it proved to be too delicate. He then tried rubber, but there were too many defects. Around 1895, he introduced discs based on shellac which is a resin secreted by female lac bugs. Shellac became the standard material until the introduction of vinyl.

Answer: Thomas Edison

The invention of the carbon microphone, also referred to as "the loose-contact transmitter," was the subject of a huge conflict in the late 1800s. On June 4, 1877, Emile Berliner applied for a patent that set off a 15-year battle between himself and Thomas Edison who filed his own patent. British-American inventor David Edward Hughes was also part of the controversy.

While Hughes revealed his findings in 1878, and may have demonstrated the device a few years earlier, he apparently never attempted to patent it. Bell paid Berliner $50,000 for the rights to his patent.

However, the United States Supreme Court finally awarded the patent to Edison in 1892.

Answer: Operating at 45 rpm

Flat discs were easier to reproduce than cylinders because they could be mass produced by stamping the disc with a metal master plate. They were also easier for consumers to store. Having the stylus vibrate side to side offered higher fidelity and prevented the stylus from jumping out of the groove which was frequent when the stylus vibrated up and down with prior records. An improved spring-driven motor provided consistency in playback speed.

Early disc recordings were produced in the range of 60-130 rpm. Eventually, 78 rpm became the standard. The first regular production 45 rpm record wasn't introduced until 1948.

Answer: Enabling a group of callers to talk to each other without direct phone lines between each subscriber

The telephone exchange was a system that could be used in a small area to enable the switching of subscriber lines for calls made between them so that each subscriber wouldn't have to be directly connected to each other. Puskás was working for Thomas Edison and, around 1876, proposed the idea of the exchange.

In 1877, the first experimental telephone exchange, based on Puskás's ideas, was built by the Bell Telephone Company in Boston and was the start of the modern telephone system. The first commercial telephone exchange in the world was started in 1878 in New Haven, Connecticut. The District Telephone Company of New Haven began operations with twenty-one subscribers who paid $1.50 per month.

Answer: False

Nikola Tesla was actually the first to build a working radio system which he demonstrated in St. Louis, Missouri, in 1893. But Tesla was apparently not focused on using radio for communication.

On the other hand, Marconi was focused on using radio for communication and, in 1895, he began field testing his system and was able to transmit signals up to 0.8 km (0.5 mi). He continued to make improvements and received a patent in 1896. However, Marconi's wireless telegraphy system communicated only using Morse Code, not voice.

Canadian-American inventor Reginald Fessenden was the first to make improvements in radio to the point that it could carry voice signals. In the fall of 1900, he successfully transmitted speech over a distance of about 1.6 km (1 mi) and is credited as being the first to successfully send audio transmission using radio.