Recently, I was talking to someone about how to properly pronounce a yod that follows a patach when it is not at the end of a word. For example, we know that words like חַי are pronounced as chai with the yod making an ie sound like “pie” but what about words like לְהַחַיוֹת , חַיֵינוּ, or וְצָהֳרָיִם? The person I spoke with insisted the the yod would create a sound exactly the same as ַי . Conversely, if we take the word חַיֵינוּ I would pronounce it cha-yeh-nu rather than chai-yeh-nu. For לְהַחַיוֹת I would pronounce it l’ha-cha-yot rather than l’ha-chai-yot. That said, one example he offered was דַיֵנּ. To provide some context, I taught myself Hebrew as an adult which makes me less confident when more experienced people talk to me about the finer details of pronunciation. It was my impression, that while both approaches sound similar in practice, there is a slight difference in that the “ie” sound only occurs when a yod appears next to a patch at the end of a word.
Generally, a syllable is closed by a consonant with a sheva na, a consonant at the end of a word, or a consonant with a dagesh chazak. Otherwise, it is an open syllable and ends in a vowel. Therefore, in your cases (in an Israeli pronunciation):
- וְצָהֳרָיִם = vetso-hora-yim
- לְהַחֲיוֹת = leha-chayot
- חַיֵּינוּ = chay-ye-nu
- דַּיֵּינוּ = day-ye-nu
For more information on syllable structure, see "Syllable structure: Biblical Hebrew."