Looking through their site, I think the optional hifi is in reference to their Blinc Bluetooth system. I see no other reference to the built-in speakers other than:
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Easy-to-use hands-free communication, BLINC I gives you the ability to take and make calls, listen to your MP3 player and GPS unit, and talk to your passenger via intercom. BLINC I is available on both full face and modular helmets.
Lithium ion battery with a power charger.
8 hours talk time, 150 hours standby.
2 Built-in speaker.
Built-in anti-noise microphone.
Incoming call overrides intercom, music, or navigation audio; terminating the call resumes audio from intercom, GPS, or MP3 player.
Multi-pairing ability with Bluetooth® equipped phone, GPS, MP3 player, etc.
100 ft intercom distance.
1 touch control for call answering, rejecting, and redialing.
Weather resistant.
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I would be stoked if their helmets had a simple speaker system with audio jack, as I have that with my snowboard helmet. But if the bluetooth system were decently priced it would be handy to not have to pull over to use my phone.