The tenor saxophone is a medium-sized member of the saxophone family, a group of instruments invented by Adolphe Sax in the 1840s. The tenor, with the alto, are the two most common types of saxophones. The tenor is pitched in the key of B♭, and written as a transposing instrument in the treble clef, sounding a major ninth lower than the written pitch. Modern tenor saxophones which have a high F# key have a range from B♭2 to E5 and are therefore pitched one octave below the soprano saxophone.