Hooker confirmed that he used an open G guitar tuning technique for his guitar, although he usually used a capo, raising the pitch to B (1948), A (1959), or A (1970). He also employed hammer-on and pull-off techniques, which are described as "a slurred ascending bass line played on the fifth string [tonic]" by music writer Lenny Carlson. Although it is titled a "boogie", it does not resemble the earlier boogie-woogie style. Boogie-woogie is based on a left-hand piano ostinato or walking-bass line and, as performed on guitar, forms the popular 1940s instrumental "Guitar Boogie". Rather than being derivative, Hooker's boogie becomes "as overwhelmingly personal a piece as anything ever done in the blues". Recording and release In September 1948, Besman arranged recording sessions for Hooker at United Sound studios in Detroit. Several songs were recorded with Hooker's vocals and amplified guitar. To make the sound fuller, a microphone was set up in a pallet that was placed under Hooker's foot. According to Besman's account, a primitive echo-chamber effect was created by feeding Hooker's foot-stomp rhythm into a speaker in a toilet bowl, which in turn was miked and returned to a speaker in the studio in front of Hooker's guitar, thus giving it a "big" or more ambient sound. Three takes of Hooker's performance were recorded, the last providing the master for "Boogie Chillen'". Even though Besman had his own record label, Sensation Records, he licensed "Boogie Chillen'" to Los Angeles-based Modern Records. On November 3, 1948, it was released nationally and Hooker commented on its immediate appeal: "The thing caught afire. It was ringin' all around the country. When it come out, every juke box you went to, every place you went to ... they were playing it there". Because of the response, Nashville, Tennessee, radio station WLAC, a 50,000 watt clear-channel station that reached fifteen states and Canada, played the song ten times in a row during one broadcast night. "Boogie Chillen'" entered the Billboard Race Records chart on January 8, 1949, where it remained for eighteen weeks, and reached number one on February 19, 1949. The Detroit Free Press, Hooker's hometown newspaper, published a favorable review on January 22, 1949: "Boogie Chillen'" became the most popular race record of 1949 and reportedly sold "several hundred thousand" to one million copies. In an experience similar to Muddy Waters' 1950 hit "Rollin' Stone", the song's popularity allowed Hooker