In chemistry, the term base metal is used informally to refer to a metal that oxidizes or corrodes relatively easily, and reacts variably with diluted hydrochloric acid (HCl) to form hydrogen. Examples include iron, nickel, lead and zinc. Copper is considered a base metal as it oxidizes relatively easily, although it does not react with HCl.

Base is used in the sense of low-born, in opposition to noble or precious metal. In alchemy, a base metal was a common and inexpensive metal, as opposed to precious metals, mainly gold and silver. A long-time goal of the alchemists was the transmutation of base metal into precious metal.

In numismatics, coins used to derive their value primarily from the precious metal content. Most modern currencies are fiat currency, allowing the coins to be made of base metal.^{[citation needed]}

In mining and economics, base metals refers to industrial non-ferrous metals excluding precious metals. These include copper, lead, nickel and zinc. The U.S. Customs and Border Protection is more inclusive in its definition. It includes, in addition to the four above, iron and steel, aluminium, tin, tungsten, molybdenum, tantalum, cobalt, bismuth, cadmium, titanium, zirconium, antimony, manganese, beryllium, chromium, germanium, vanadium, gallium, hafnium, indium, niobium, rhenium and thallium.

Denis Arthur Smalley (born 1946 in Nelson, New Zealand) is a composer of electroacoustic music, with a special interest in acousmatic music.

Denis Smalley studied at the University of Canterbury and Victoria University in his native New Zealand, and later at the Paris Conservatoire with Olivier Messiaen, with the Groupe de Recherches Musicales (GRM), and at the University of York, in England, where he has lived since 1971. He also studied with Musique concrète pioneer François Bayle.^{[citation needed]}

He initially composed onto tape, but as early as the 1980s realised his works using computer software. His composition Pentes (1974) is regarded as one of the classics of electroacoustic music. Source sounds for his works may come from the environment—and are often the starting point for his pieces—but he may also develop highly sophisticated timbres from scratch using computer software. He describes his approach as "spectromorphological", featuring the development of sounds in time.

A lecturer at the University of East Anglia, England, from 1976 to 1994, he has been professor of music at City University, London since 1994, where he currently teaches electroacoustic composition and is the Head of the Music Department.^{[citation needed]}