Speech Synthesis works on Safari iPad in iframe but not in event sheet

I'm trying to get speech synthesis to work on Safari on the iPad/iPhone.

When using the C3 plug-in it does not work (only works on a PC), however, when I use JavaScript code in an iframe, it does work.

Here I have two ways to do the speech:

First way is with a sprite, when touched it will call a JS function and say the phrase. This does NOT work on Safari on iPad (but does on a PC).

Second way is in an iFrame, using the same speech function. This works in on Safari.

Why wouldn't the function work when the sprite is touched on Safari, when the iframe buttons work?

https://1drv.ms/u/s!AobC4q3rBlr65IhYl02rKCS0ATJFcQ?e=PKdRCx