Seoul, South Korea -- A dollar can buy a pack of gum, a can of soda or a bag of chips. And in South Korea, it can buy an opportunity to sing karaoke.

In South Korea, karaoke, locally called noraebang, has been a culturally important leisure activity for decades. Now it's evolving further to better meet singers' needs.

So-called coin karaoke has emerged as a way for people to have more control over how much time and money they spend on one of their favorite pastimes.

Coin karaoke works like a vending machine, where one can begin by inserting coins or paper money.

"I love coin karaoke," said Jason Li, a college senior who's been practicing k-pop boy band BTS’ song "DNA" recently. "I come here every other day to relieve stress. It’s a routine now."

It's becoming routine for many in South Korea, which now boasts more than 1,900 registered coin karaoke machines among a total of more than 35,000 total karaokes, according to the Ministry of Culture and Sports.

Coin Rock Star, a company that makes the machines, said inquiries from potential customers have increased more than 160 percent from January 2017 to January 2018.

"Most of the new karaoke businesses are considering bringing in coin karaoke," said an official from TJ Media, a company that makes karaoke machines. "Given the same area, coin karaoke rooms are twice or three times smaller than the original ones, so it is more economical for the owner."

Coin karaoke booths are compact, with most designed to fit no more than two people. There's usually one remote control, two microphones, the display screen and a slot to insert money. For 500 Korean won, about 50 cents, a user can sing one song, although prices vary slightly. There are change machines outside the booths so customers can exchange large bills for smaller bills.

This shift to shorter singing sessions is dramatic when compared with spending much more money up front to book a room for an hour or for multiple hours, often with a large group to help defray the costs. In short, it gives more people more opportunities to sign more frequently.

"I come to coin karaoke because I can practice singing at a reasonable price," Kim Do Hyun, a customer who stops by coin karaoke at least once every week, told ABC News.

Customers said they don't feel pressured to finish songs quickly or keep singing to fill a whole hour that was booked in advance. And singers also get to enjoy up-to-date track lists, many of which are updated every day to reflect current musical trends.

"The rooms are quite small, so you can sing alone or with an intimate group," Park Jae Young, who came to sing a ballad for herself after school, told ABC News. "It gives convenient entertainment because you can come here any time you want, and there is no need to make a reservation."