Wilson's Wall of Sound-based orchestrations mixed conventional rock set-ups with elaborate layers of vocal harmonies, found sounds, and instruments never before associated with rock, such as bicycle bells, French horn, flutes, Electro-Theremin, string sections, and beverage cans. The album consists mainly of introspective songs like "I Know There's an Answer", a critique of LSD users; and "I Just Wasn't Made for These Times", the first use of a theremin-like instrument on a rock record. Its unprecedented total production cost exceeded $70,000 (equivalent to $ in ). In October, the leftover song "Good Vibrations" followed as a single and became a worldwide hit. In 1997, a "making-of" version of "Pet Sounds" was overseen by Wilson and released as "The Pet Sounds Sessions", containing the album's first true stereo mix.