>"Oishii" means delicious in Japanese and it seems something that makes sense to say whilst you are smiling at enjoying your food. The long "ii" vowel to rhyme with the "e" of "she" in English.

Honestly, I don't necessarily agree. For example in Japanese 'iie' sounds very similar to 'yes' or 'yeah' but it actually means the opposite, it means 'no', whereas 'hai' means 'yes'.

If we want to talk about individual phonemes caused by emotional reactions, there might be some truth behind what you're saying, however as soon a we enter the realm of "this word sounds soft so it's positive" and "this word sounds hard hence it's negative" everything collapses.

Obviously you can find tons of examples of words that are different in different languages. I probably confused the situation by bringing Japanese in. My son is Japanese so we talk in Japanese to a baby. I wasn't trying to compare languages. I was trying to talk about baby words.

Yeah it falls apart at any level of complexity.

I just think there are certain cases in often used words and words that babies say or hear a lot at first. Like the mama/haha/papa/baba words. I'm talking about a 'language' in the same way the article talks about an animal language. Like a few often used words linked to emotional states.

I don't mind if you disagree I just happen to believe oishii may be one of these words.

all predicate adjectives in Japanese end in -i ookii, chisai, mazui, etc. the -i is the suffix indicating it is a predicate

oishii thus means "is delicious" - you don't need a "da" after it

I made a mistake by bringing Japanese into it - see my other comment. It's the language we speak at home so the one I use to talk to our son. The emphasis was supposed to be on baby-talk not foreign languages.