Enabling the Siri confirmation "beep" when holding the home button down?

On the iPhone 6 Plus (which doesn't have Hey Siri unless connected to power) prior to the upgrade to iOS 10, Siri would confirm that it was ready when holding the home button down with a "beep" sound. Since iOS 10 there is just a visual cue that it is ready. There is also a vibrate feedback, but that is subtle.

The problem for my 97 year old friend with an iPhone 6 Plus is that he has trouble confirming visually that Siri is ready. And he doesn't notice the vibrate. He was used to the "beep."

Is there a way of restoring that beep confirmation on the iPhone 6 Plus? On my iPhone 6 Plus I tried all the Siri settings but none of them seemed to help restore the beep.

He is having trouble phoning me now because he is having trouble getting Siri to work.