"Pet Sounds" includes tempo changes, metrical ambiguity, and unusual tone colors that, in the opinion of author James Perone, remove the album from "just about anything else that was going on in 1966 pop music". He cites the album's closer "Caroline, No" and its use of wide tessitura changes, wide melodic intervals, and instrumentation which contribute to this belief; also Wilson's compositions and orchestral arrangements which experiment with form and tone colors. Wilson's arrangements combined traditional rock set-ups with unconventional selections of instruments and complex layers of vocal harmonies. His orchestrations, in terms of the choices of instruments themselves and the stylistic appropriation of foreign cultures, were similar to those by exotica producers such as Martin Denny, Les Baxter, and Esquivel. Many of the instruments were alien to rock music, including glockenspiel, ukulele, accordion, Electro-Theremin, bongos, harpsichord, violin, viola, cello, trombone, Coca-Cola bottles, and other odd sounds such as bicycle bells.