In Middle English, intrusive consonants sometimes appeared in certain phonetic environments. These consonants tended to appear especially before ME /l/, /r/, and /n/.
1. Intrusive /b/ sometimes appeared after /m/ and before /l/, /r/, or /n/. For example, OE bremel /bremel/ "bramble" became ME bremble /bremb'l/; OE næmel /næ:mel/ "nimble" became ME nimble /nImb'l/.
2. Intrusive /d/ sometimes appeared after /n/, either in final position or before /l/, /r/, or /n/.
3. Intrusive /t/ sometimes appeared after /s/, either in final position or before /l/, /r/, or /n/.