Living in Merseyside, I've noticed a phonetic oddity that I can't find described anywhere [I did a Web search and found a transcript of Liverpool speech on a Liverpool University site, but no mention of the following]. When single-syllable words end in T, the T is dropped but, if I'm hearing correctly, the whole syllable is aspirated. Voiced consonants are still voiced but also aspirated. So 'but' is pronounced /bʰʊʰ/, 'not' pronounced /nʰɒʰ/ and 'that' pronounced /ðʰaʰ/. Is this a recognized phenomenon, and if so, is it confined to Liverpool?
There is no such thing as, "The whole syllable is aspirated." What you are describing is breathy voicing of the vowel, probably. 'Tis not aspiration.
Non-nasal stops may be aspirated. In some languages, voiceless (non-nasal) stops can be preaspirated, but typically aspiration occurs upon the release of the stop. Both voiced and voiceless stops can be aspirated, as shown in many languages of the Indian subcontinent.