Allophone
Allophone, one of the phonetically distinct variants of a phoneme (q.v.). The occurrence of one allophone rather than another is usually determined by its position in the word (initial, final, medial, etc.) or by its phonetic environment (Britannica).
We define an “allophone” as a speech segment with a distinct acoustic realization that can be context dependent and position specific, but not necessarily so (e.g., English /l/ has “light” and “dark” allophones, [l] and [ɫ],1 which are position specific; but English /f/ has only one allophone, [f], which appears in different positions) (Holger Mitterer, Eva Reinisch, James M. McQueen).
Britannica, T. Editors of Encyclopaedia (2018, February 26). allophone. Encyclopedia Britannica. Retrieved from: https://www.britannica.com/topic/allophone.
Mitterer, H., Reinisch, E., & McQueen, J. (2018) Allophones, not phonemes in spoken-word recognition. Journal of Memory and Language (Vol. 98, pp. 77-92).