The worldwide market for wearable devices, now inclusive of wireless headphones with smart assistants, is forecast to grow 15.3% over the previous year to 198.5 million units by the end of 2019, according to the International Data Corporation (IDC) Worldwide Quarterly Wearable Device Tracker.   Driving that growth will be the continued proliferation of watches, ear-worn devices, and wrist bands as well as further adoption in the healthcare segment. Looking ahead, the market is expected to reach ...