1. How Edison's 1877 tin foil phonograph recorded sound and how often it could be played
In 1877, Edison invented the phonograph. It worked by scratching grooves into a cylinder wrapped with thin tin foil to record sound waves [1]. When a needle traced the groove again, the vibrations returned as sound. However, the tin foil was weak. After a few plays, it tore, and the recording could never be heard again [1].
Devices that recorded sound shapes on paper existed before Edison’s machine. But at that time, those records could not be played back as sound [9] [10]. Edison’s machine is considered the first machine that could play back recorded sound [9]. Just being able to preserve a voice was a huge event. But you could not "listen and enjoy it repeatedly." The next challenge was to create a container that lasted longer and held more music.
2. How cylinders and discs were limited to about 3 to 5 minutes of music
After tin foil, cylinders were made of wax. Early versions wore out after about 20 plays, but by the early 1900s, they could be played more than 100 times. Still, the maximum recording time was about 3 minutes. Later, "4-minute" Amberol cylinders appeared, but the length depended on the standard [2].
In the 1910s, the competing disc format became the market standard, and Edison’s cylinder production ended in November 1929 [2]. But discs also had a time limit. Home records before the LP were made of shellac and spun at about 78 revolutions per minute. Even a 12-inch disc held less than 5 minutes per side [3]. In Japan, the Nippon Phonograph Company (later Nippon Columbia) is said to have started selling domestic disc-based phonographs in 1910 [6]. The length of the container directly set the limit on "how long you could listen at once." The next goal was to extend that time.
3. How the 1948 LP used slower rotation and narrower grooves to hold more music
In 1948, Columbia introduced the LP (Long Play). Development was led by a team including Peter Goldmark at the CBS Research Institute, with a reported goal of "more than 20 minutes per side." The LP spun at 33 1/3 revolutions per minute, used vinyl material, and featured narrow "microgrooves," holding about 20 to 25 minutes per side (estimates vary by source) [3].
Compared to the 78 rpm shellac records that held less than 5 minutes, the listening time increased many times over. Long pieces of music could now be heard in one go. However, the LP did not spread instantly. In the US, LPs made up only 17% of sales volume in 1952. By the early 1960s, they reached about 25% by volume and 58% by value [3]. Even when a new container appears, replacement takes time if people and markets still use the old format.
4. Why the CD is 12 cm wide and holds up to 74 minutes: several theories
CD manufacturing began on August 17, 1982, in Langenhagen, West Germany. The first disc is said to have been ABBA’s *The Visitors*. It is 12 cm in diameter and can hold up to 74 minutes [4]. The world’s first commercial CD player, Sony’s CDP-101, was released in Japan on October 1, 1982, for 168,000 yen [5]. Note that the CD came out in August, but the player followed in October.
Why 12 cm and 74 minutes? Philips argued for 11.5 cm and 60 minutes, while Sony pushed for 12 cm and 74 minutes. It is said that Sony’s Norio Ohga wanted a size large enough to fit Beethoven’s Ninth Symphony without the opera curtain falling in the middle. Some theories link this to a 1951 performance by Furtwängler at Bayreuth [4]. However, the German tech magazine *heise* suggests that practical reasons, such as Sony’s manufacturing readiness, likely played a larger role [4]. There are several theories, so the famous "Ninth Symphony" story alone is not the definitive answer.
5. How streaming reached record sales in 2024 while CDs did not disappear
According to the Recording Industry Association of Japan (RIAJ), digital music sales in 2024 reached 123.3 billion yen (106% of the previous year), marking the 11th consecutive year of growth and an all-time high. Streaming accounted for 113.2 billion yen, or 91.8% of digital sales. Note that this 91.8% is the share within digital sales, not the entire music market [7].
Did CDs lose? In the same year, CD production was 62.52 million albums and 41.98 million singles, totaling about 104.5 million units. The production value of physical music software (including vinyl and DVDs) was 205.2 billion yen, which is larger than the 123.3 billion yen from digital sales [7]. While streaming is definitely growing, CDs still play a significant role in Japan. It is too early to say, based on the numbers, that "streaming has replaced CDs."
6. How new analog records grew about 22 times in the streaming era
Another surprise is the growth of analog records. In 2024, Japan produced 3.15 million analog discs (117% of the previous year) worth 7.9 billion yen (126% of the previous year). This exceeded 7 billion yen for the first time in 35 years, since 1989 [7].
New analog titles reportedly increased from 41 in 2011 to 900 in 2024, a roughly 22-fold increase (this figure comes from a summary article) [8]. However, the 7.9 billion yen value is about 4% of the total physical music production value of 205.2 billion yen. It is accurate to view this not as a return to the mainstream, but as a small but definitely growing sector [7]. The statistics used here do not explain why vinyl production is growing. Try thinking about the reasons yourself.
7. How you can investigate CD size and playing time at home
If you have a CD at home, measure its diameter with a ruler and check the playback time. Comparing discs with times close to 74 minutes to those that are much shorter can help you realize that "how many minutes fit on one disc" was a choice made by the creators.
You can also visit libraries or used record stores. Compare the size of LPs and singles with the amount of information on their jackets. For official data, you can read the original numbers in the RIAJ statistics or the National Park Service’s explanation of the Edison National Historical Park.