All About Sound, Vol. 3: Advances in Audio Quiz

Answer: Pittsburgh, Pennsylvania

KDKA transmitted the first scheduled radio broadcast on Nov. 2, 1920. The live returns of the Presidential election between Warren G. Harding and James Cox were announced. Westinghouse was also one of the founding owners of the Radio Corporation of America (RCA). In 1926, RCA established the National Broadcasting Company (NBC), a group of 24 radio stations that made up the first radio network in the United States.

As of 2024, KDKA (1020 kHz) has a news/talk radio format and operates with a transmitter power of 50,000 watts. The station can be heard throughout central and western Pennsylvania, along with portions of adjacent states.

Answer: An optically read transparent wave on the edge of the film

"Talkies," movies with sound, revolutionized the movie industry in the 1920s. The most common format for adding sound to film has been to have a translucent line running down a strip on the edge of the film. Sound is encoded into the varying width of the line in a wave pattern and is called the variable area method. A lamp, called an 'exciter', shines through the translucent waveform printed on the film strip. The light is focused onto a photodetector which transforms the optical signal into an electrical signal. This signal is then amplified and drives the speakers.

The earliest sound recordings for use in movies were on separate records. In the early 1930's sound-on-disc was replaced by sound-on-film. Early sound-on-film utilized a variable density system. During the recording process, sound waves would cause fluctuations in a light source, which in turn causes variations in exposure on the printed track. This method of optical recording was replaced by the variable area system explained above in the 1940s.

Magnetic strips on film have also been used and have some advantages. However, it is more expensive than optical recordings and magnetic recordings have not lasted as long as optical ones so optical recording has remained the standard.

Answer: Western Electric Company

Early recordings were made mechanically. The sound was collected by a horn and piped to a diaphragm (a type of membrane) which was connected to and vibrated the cutting stylus. The person being recorded nearly had to put their face in the recording horn to get decent results.

Engineers at Western Electric mastered the technology for capturing sound with a microphone and amplifying it with vacuum tubes. The result was much more lifelike sound reproduction. The Victor and Columbia record companies licensed the new electrical system and produced the first electrically recorded discs in 1925.

Answer: FM stands for fidelity modulation

FM stands for frequency modulation and was invented by American engineer Edwin Armstrong in 1933. The sound is encoded into variations (modulation) of the carrier wave frequency rather than variations of the amplitude as occurs in AM (amplitude modulation). FM broadcasting offers higher fidelity, which means more accurate reproduction of the original sound, compared to AM broadcasting.

It is also less susceptible to a variety of forms of noise, including static and popping sounds, which are heard on AM. FM radio stations use the VHF (very high frequency) range of radio frequencies.

Answer: In the 1950s, commercial vinyl records were primarily produced for 78 rpm

Emile Berliner, inventor of the gramophone, began making disc records out of shellac around 1895. Shellac remained the standard material until the transition to vinyl. Vinyl is indeed short for polyvinyl chloride (PVC), a common type of plastic.

Columbia Records introduced two 33 1/3 rpm LP (long play) options in 1948 at 10 inch (25.4 cm) and 12 inch (30.5 cm) diameters. Originally not wanting to license the LP format, RCA Victor came out with a 7 inch (17.8 cm) 45 rpm record with a large hole in early 1949. The 12 inch LP and 45 rpm both became popular and gradually replaced 78 rpm records in the 1950s.

Answer: Bing Crosby

During World War II, John T. "Jack" Mullin had been assigned to analyze German radio technology. He obtained some units of the Magnetophon which was a pioneering reel-to-reel magnetic tape recording system. In 1946, he demonstrated the device to a meeting of radio engineers. Word got back to Bing Crosby, who was one of the first entertainer/entrepreneurs. With Mullin as a consultant, Crosby began to use the Magnetophon to record his radio programs. Mullin entered an arrangement with the electronics company Ampex to supply the equipment and recording medium while Crosby provided financing. Ampex and reel-to-reel technology took off from there.

Answer: Less expensive

The use of transistors, instead of vacuum tubes as the amplifier elements in radios, meant that the radios could be much smaller, required far less power and were more resistant to physical shock than radios with delicate glass vacuum tubes. The Regency TR-1, the world's first commercially produced transistor radio, started being sold in 1954.

It retailed for around $50, which translates to nearly $400 today. Basic tube radios of the same era cost around $20.

Answer: Sony

The Walkman, first introduced in 1979, revolutionized the portable music listening experience providing high quality sound in a small package and at a reasonable price. The Walkman was extremely popular and became an icon of 1980s culture. It helped cassette tapes outsell vinyl for the first time in 1983.

In 1986, the word "Walkman" was entered into the Oxford English Dictionary. By 1989 over 100 million Walkmans had been sold worldwide.

Answer: Optically

CDs have a track, with tiny pit and "land" areas, which are arranged in a continuous spiral. These pit and land areas represent data recorded in binary form (zeros and ones). Laser light is focused on these tracks and data is read by detecting the pattern of the reflected light so the data is read optically.

Answer: Digital encoding is in a form that is more like the original sound

Electrical analog recording involves using a microphone to turn the original sound into electrical signals and recording a waveform representation of the signal onto the recording material. An analog representation is a continuous smooth wave that contains all the original acoustical information picked up by the microphone. Since sound is a waveform pattern, the analog representation is like the original.

Digital systems take the electrical analog representation and sample it (take readings of the signal level) many times a second. The sampled quantities are converted to a binary numerical representation.

Digital has some major advantages over analog. For sound reproduction, perhaps the biggest advantage for digital is low noise. Storing the sound as a series of zeros and ones makes it less likely that distortions of the data will occur compared to storing an analog waveform. Digital recordings are also less prone to wear and tear and are easier to duplicate and distribute. Digital storage devices are small and can contain a lot of data.