I noticed that some words have a bracketed sound in their transcriptions in some dictionaries, for example, see the following from Lexico:
- locate - /lə(ʊ)ˈkeɪt/
- open - /ˈəʊp(ə)n/ (I assume here the bracketed schwa sound represents syllabic "n")
And the case of "length" is more interesting, Lexico gives two transcriptions:
- /lɛŋ(k)θ/ -- with "(k)"
- /lɛn(t)θ/ -- with "(t)"
I couldn't find any other examples. What does a sound in brackets mean in the transcription of a word?