In music, sustain is a parameter of musical sound over time. As its name implies, it denotes the period of time during which the sound remains before it becomes inaudible, or silent.

Additionally, sustain is the third of the four segments in an ADSR envelope. The sustain portion of the ADSR envelope begins when the attack and decay portions have run their course, and continues until the key is released. The sustain control is used to determine the level at which the envelope will remain. While the attack, decay, and release controls are rate or time controls, the sustain control is a level control.

Drum percussion instruments are usually the instruments with the shortest sustain; a drum beat begins to fade almost instantly. Instruments with the highest possible sustain often involve the passage of air, such as brass or the pipe organ, which have theoretically unlimited sustain. Resonating instruments such as the piano and guitar also have fairly long sustain for string instruments.

Within a family of instruments, sustain is affected by a variety of factors. For example, sustain in guitars is determined by factors including body construction (hollow versus solid), body woods, neck woods, the placing of strings (through the body or atop the body), strings gauge and pickup design.

Joseph "Joe" Satriani (born July 15, 1956) is an American instrumental rock guitarist of Italian origin, multi-instrumentalist and multiple Grammy Award nominee. Early in his career, Satriani worked as a guitar instructor, and some of his former students have achieved fame such as Steve Vai, Larry LaLonde, Rick Hunolt, Kirk Hammett, Andy Timmons, Charlie Hunter, Kevin Cadogan and Alex Skolnick. Satriani has been a driving force in music credited to other musicians throughout his career, as a founder of the G3 tour, as well as performing in various positions with other musicians.

In 1988, Satriani was recruited by Mick Jagger as lead guitarist for Jagger's first solo tour. In 1994, Satriani was the lead guitarist for Deep Purple. Satriani worked with a range of guitarists, including Steve Vai, John Petrucci, Eric Johnson, Larry LaLonde, Yngwie Malmsteen, Brian May, Patrick Rondat, Andy Timmons, Paul Gilbert, Adrian Legg, and Robert Fripp through the annual G3 Jam Concerts. He is currently the lead guitarist for the supergroup Chickenfoot. Since 1988, Satriani has been using his own signature guitar, the Ibanez JS Series, which is sold in music stores worldwide.

Lester William Polsfuss (June 9, 1915 – August 13, 2009)—known as Les Paul—was an American jazz and country guitarist, songwriter and inventor. He was the inventor of the solid-body electric guitar which made the sound of rock and roll possible. He is credited with many recording innovations. Although he was not the first to use the technique, his early experiments with overdubbing (also known as sound on sound),delay effects such as tape delay, phasing effects and multitrack recording were among the first to attract widespread attention.

His innovative talents extended into his playing style, including licks, trills, chording sequences, fretting techniques and timing, which set him apart from his contemporaries and inspired many guitarists of the present day. He recorded with his wife Mary Ford in the 1950s, and they sold millions of records.

Among his many honors, Paul is one of a handful of artists with a permanent, stand-alone exhibit in the Rock and Roll Hall of Fame. He is prominently named by the music museum on its website as an "architect" and a "key inductee" along with Sam Phillips and Alan Freed.

Bradley "Brad" Carlton (born George Kaplan) was a fictional character on CBS soap opera The Young and the Restless. Actor Don Diamont played the role since May 1985 until he departed the show in 1996 and returned on July 28, 1998. Diamont was temporarily replaced by Russell Todd in 1993. The character has also appeared on The Bold and the Beautiful briefly in 1993. In December 2008, it was announced that Diamont had been released from his contract. His final air date was on February 5, 2009.

Brad Carlton was first introduced as the Abbotts' gardener, who caught the eye of the youngest Abbott daughter, Traci. The two were married twice, with the second marriage producing a daughter, Colleen Carlton. During his second marriage to Traci, Brad was held captive in a cage by his unstable ex-wife, Lisa Mansfield. After he divorced Traci, Brad was tricked into marrying the wealthy widow, Cassandra Rawlins, after a ski trip to Aspen. Brad eventually returned to Genoa City with plans to divorce Cassandra, but en route to finalize her divorce plans, Cassandra was hit by a truck and killed. Brad inherited her fortune and her estate. Throughout his on-and-off relationship with Traci, he had feelings for her sister, Ashley Abbott. They eventually married, and he adopted her daughter who was given his last name, Abby Carlton. Ashley was pregnant with Brad's child, but she lost the baby in a car accident. They split up, and he later married Victoria Newman in November 2006.