Here's how you can extend the life of your iPhone, iPod or iPod Touch by disabling Siri's Raise to Speak feature.
1. Open the Settings app.
2. Tap on General.
3. Tap on Siri.
4. Toggle the Raise to Speak switch to the Off position.
This will help save battery power so you won't need to recharge your iPhone, iPod Touch or iPad as often.