[neild]

It doesn't talk out loud if you hold the phone up to your ear. To use Siri with minimal noise (aside from your own speech):

Push the power button to turn on the screen. Hold the phone to your ear. Wait for the be-beep sound, played quietly through the ears-only speaker. Speak. Keep the phone against your ear. Siri will respond through the ears-only speaker.

[bretthoerner]

That's exactly what the parent said he doesn't want to do.

[neild]

Aha! I misread the parent's "she" as referring to Siri, not as to the person using the phone. Apologies.