Acronyms and letter sequences

At this stage it is worth mentioning two other types of word/token relationships that are often cited as problems for TTS. Acronyms are words formed from sequences of other words, usually (but not always) by taking the first letter of each. Examples include NATO, UNICEF SCUBA and AIDS. In our approach, these are treated as normal words so that we have a word NATO in our lexicon and this has a pronunciation /n ey t ow/ the fact that this was historically formed from other words or is normally found written in upper case is of no real concern. (In fact, with use many acronyms really do become indistinguishable from normal words such that radar is nearly always spelled in lower case and few people realise that it is an acronym, and fewer still what the original words were). 

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