Heart sounds are the noises generated by the beating heart and the resultant flow of blood through it (specifically, the turbulence created when the heart valves snap shut). In cardiac auscultation, an examiner may use a stethoscope to listen for these unique and distinct sounds that provide important auditory data regarding the condition of the heart to a trained observer.

In healthy adults, there are two normal heart sounds often described as a lub and a dub (or dup), that occur in sequence with each heartbeat. These are the first heart sound (S₁) and second heart sound (S₂), produced by the closing of the AV valves and semilunar valves respectively. In addition to these normal sounds, a variety of other sounds may be present including heart murmurs, adventitious sounds, and gallop rhythms S₃ and S₄.

Heart murmurs are generated by turbulent flow of blood, which may occur inside or outside the heart. Murmurs may be physiological (benign) or pathological (abnormal). Abnormal murmurs can be caused by stenosis restricting the opening of a heart valve, resulting in turbulence as blood flows through it. Abnormal murmurs may also occur with valvular insufficiency (or regurgitation), which allows backflow of blood when the incompetent valve closes with only partial effectiveness. Different murmurs are audible in different parts of the cardiac cycle, depending on the cause of the murmur.

Nathaniel Joseph "Nature" Ruess (February 26, 1982) is an American indie/indie pop singer-songwriter from Arizona. Ruess was the singer of The Format and currently lead vocalist of the band Fun.

Nate was born February 26, 1982 in Iowa City, Iowa. He was the youngest of two children, his sister Libbie being one year older.

In 1986, his family moved to a farm in Glendale, Arizona, where he remained throughout his childhood. He attended Deer Valley High School and graduated in 2000. Having an uncle, John Ruess, who performed on Broadway, Ruess was always somewhat interested in music and performing. He joined punk bands in high school and, upon graduation, chose to pursue music instead of attending college. He never took formal singing lessons or learned to play an instrument and was often told by peers that he lacked the talent to make it professionally. He took a job in a law firm as a way to support himself while he pursued his musical ambitions.

In 2001, at the age of 19, he launched the band The Format with his longtime best friend, Sam Means. This was his first musical endeavor to garner widespread attention.

Pierre David Guetta (7 November 1967), known professionally as David Guetta (French pronunciation: [daˌvid ɡɛˈta]), is a French house music producer and DJ. Originally a DJ at nightclubs during the 1980s and 1990s, he co-founded Gum Productions and released his first album, Just a Little More Love, in 2002. Later, he released Guetta Blaster (2004) and Pop Life (2007). His 2009 album One Love included the hit singles "When Love Takes Over" (featuring Kelly Rowland), "Gettin' Over You" (featuring Chris Willis, Fergie & LMFAO) and "Sexy Bitch" (featuring Akon), the last becoming a top five hit in the United States and all three reaching #1 in the United Kingdom, as well as another internationally known single called "Memories" featuring Kid Cudi which became a top five hit in many countries. Guetta has sold over three million albums and 15 million singles worldwide. He is currently one of the most sought-after music producers. As at 2012 David Guetta is the world's most popular DJ, claiming the #1 poll position of the DJ Mag 100 popularity poll.

Katheryn Elizabeth Hudson (born October 25, 1984), known by her stage name Katy Perry, is an American singer, songwriter and actress. Perry grew up with gospel music, and during her first year of high school she pursued a music career as Katy Hudson, releasing her first studio album called Katy Hudson which failed to chart. She recorded a solo album later, which was never released. After signing with Capitol Music Group in 2007, her fourth record label in seven years, she adopted the stage name Katy Perry.

She first gained recognition with the release of her first mainstream album, One of the Boys in 2008, which spawned three Billboard Hot 100 top-ten songs—"I Kissed A Girl", "Hot n Cold" and "Waking Up In Vegas". Perry supported the album with her Hello Katy Tour. In 2010, her third studio album, Teenage Dream (2010), which topped the Billboard 200 chart, and spawned five number one singles—"California Gurls", "Teenage Dream", "Firework", "E.T." and "Last Friday Night (T.G.I.F.)"—Teenage Dream was the only album (after Michael Jackson's Bad)—to do so, and the first female in history to achieve this milestone. She embarked on the California Dreams Tour, which grossed nearly $60 million worldwide. Perry re-released the album under the name of Teenage Dream: The Complete Confection on March 26, 2012, and the re-release has already spawned the number-one single "Part of Me".