Ha Suse, I'd read that we instinctively use a higher pitched voice with babies because they respond better to that - spose there's a difference between soothing sing-song and annoying screeching though!

I guess it really depends on what stage your child is at - for us, any verbal communication Riv made would be fantastic! If he says 'ta' I'll be super happy that he's saying 'ta' and not ummph that means ta. Then when he starts to say ta consistenly, perhaps I'll start to suggest he say thankyou instead. Kids can relearn things, they do it all the time!