Most of DS' words aren't very clear - DH and I often have to translate for friends. For instance, dog is 'guh' and duck is 'cuh' - he's sounding out the last sound in the word. Some words he will only say the first part, e.g. bus is 'buh' and bag is 'ba'. On the other hand, he is able to say 'beep' and 'woof' quite clearly.
The main thing I've noticed is that he doesn't seem to be able to say two syllable words unless the sound is reduplicated. For instance, he will happily say 'booby' (pointing proudly to his own moobies ), but he will pronounce buggy as 'bubby'. Likewise, a digger is 'diddah', nappy is 'nanny', monkey is 'mummy' (great!) and play-doh is 'bay-bo'...and so on. The only exception to this seems to be the word flower, which he pronounces 'vow-wuh'.
A couple of words bear absolutely no relation to their proper pronunciation - a cat is a 'da-ah' and a banana is a 'ma'.
Should I just let him get on with it, or are there ways I can help him sound out the words? I already try to make sure I answer him with the correct word, yet not correct him, e.g. he will point at a digger and say 'diddah', and I will answer, "Oh yes, there's a digger!"
I don't have any books on child development and haven't seen the health visitor in ages, so have no idea what sounds a typical 19 month old should have mastered - advice/ideas therefore appreciated!
I have a 19 month DD and she is very similar - although I don't think she says as many words! She vey rarely says anything if there is any one other than me or DH around although she does at nursery). She only says probably about 20 words and very few are said perfectly! eg. she says 'Daddin' for Daddy, and 'mamma' for mummy, 'choo' for shoes, 'bow' for ball etc etc. All quite normal as far as I am concerned. Your DS sounds like he is having a good go at saying lots of things and before too long he will be saying more things and a lot clearer - nothing to worry about and talking to him about all sorts of things will help him pick things up.
DS is 21 months and his pronounciation has come on in leaps and bounds in the past month or so, all of a sudden, so don't worry at all I also think you're doing just the right thing with 'oh yes, it's a digger!', that's exactly what I do too
He sounds normal to me! My DS was the same at that age, saying words similar to yours but all of a sudden he started saying some words properly. Even now his words aren't always clear and I often have to translate for people but he is getting there. Like you we just repeat the words correctly and they soon pick it up.