How to detect that we are on the current page while we r reading epub3?

Hi Everyone,

Im newer of using epub3. I'm trying to product an audio epub3 and i set display option "open-to-spread = true", when i slide first page, an audio will be played auto but for ibooks, when we slide first page, the second page already load before i open it. My question is that are there any way to detect that we are on current page?

Sorry for my enlish language

Thank in advance