Just to be clear, I can speak to Google NOW, it just won't answer my inquiries with a synthesized voice. I first noticed this the other day when I read about an "easter egg" on Droid-life. Apparently, if you say "Beam me up Scotty" to Google Now it comes back with a cute line from the original Star Trek series which it speaks outloud with its synthesized voice. I tried it on my Nexus 7, and it worked like a charm. I then tried it on my S4, and nothing.
BTW, I greatly appreciate the help.
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Verizon pushed 4.3 several weeks ago.
I misunderstood your question. I just tried "Beam me up Scotty" - its computerized voice told me "I dunna have the power". I'll try going through settings and see if something will turn that off, which you could then use to turn it on.
EDIT: Here's the Google help section on Voice - take a look at "speech output" - maybe you have handsfree only turned on so the voice will only work if headphones are plugged in?
Voice settings
Voice settings control different aspects of speech input and output when you search by voice or use Voice Actions:
Language. The language you select here for Voice Search input and output can be different from the language displayed by your device.
Speech output. To turn on speech output only when you've got a headset attached to your device, select Hands-free only.
Block offensive words. Check to ensure that search results with offensive language are blocked.
Hotword detection. When this is checked, you can say "Google" when viewing the Google Now screen rather than touching the Microphone icon to initiate a voice search or action.
Offline speech recognition. Choose to select one or more additional languages for speech recognition when you don't have a network connection.
Google Account dashboard. Manage the data for your Google Account.
Bluetooth headset. Perform voice searches or actions using a Bluetooth headset.