After iOS7 upgrade Siri only works with "Raise to Speak"

Upgraded to iOS 7 earlier today on my iPhone 5. Now Siri will now only respond if I set it to "Raise to Speak" and do so. Holding the home button does bring up the Siri interface, but nothing I say is recognized and I soon get the low-pich double tone of Siri timing out. Siri works normally if my iPhone is to my ear. Odd and unacceptable. Anyone else experience this? More important, anyone have any solution? I've tried toggling Siri on & off, hard resetting, erasing settings & rebooting, and toggling off then on around a hard reset. Frustrating. Thx.