[...] the best way to pose the problem of the psychology of speech sounds is to compare an actual speech sound with an identical or similar one not used in a linguistic context. It will become evident almost at once that it is a great fallacy to think of he articulation of a speech sound as a motor habit that is merely intended to bring about a directly significant result.
- Sapir (1925), a pag.33

[...] the articulation of the 'wh'-sound in such a word as 'when' has no direct functional value; it is merely a link in the construction of a symbol, the articulated or perceived word 'when', which in turn assumes a function, symbolic at that, only when it is experienced in certain linguistic contexts, such as the saying or hearing of a sentence like 'When are you coming?'.
- Sapir (1925), a pag.34

[...] a speech sound is not merely an articulation or an acoustic image, but material for symbolic expression in an appropriate linguistic context. Very instructive is our attitude towards the English sounds 'j', 'ŋ' and 'ts'. All three sounds are familiar to us (e.g., 'azure', 'sing', 'hats'). None occurs initially. For all that, the attempt to pronounce them initially in foreign words is not reacted to in the same way [...]
- Sapir (1925), a pag.44