Bluetooth headphone sales surpass others for first time, with Apple's Beats in top spot

During the first six months of the year, Bluetooth models accounted for 54 percent of dollar sales and 17 percent of unit sales, NPD said. Whereas the U.S. headphone market as a whole grew dollar sales 7 percent year-over-year, Bluetooth figures surged 42 percent.

Together, Beats and second-place LG controlled 65 percent of dollar sales in the first half of 2016. Following behind in the top five were Bose, Jaybird, and Skullcandy.

NPD linked the growth of the Bluetooth market to promotions and new products, as well as a lower average sales price, down 5 percent. 30 percent of headphones sold cost $50 or less, versus just 16 percent in 2015.

Bluetooth headphones — particularly those from Beats — have often commanded a high premium. Wireless versions of Beats' Solo2 headphones, for instance, are still $100 extra at $300, and Apple charges a $50 premium for the Bluetooth versions of its Powerbeats2 earbuds.

The segment will probably do even better if Apple drops 3.5mm headphone jacks from this year's iPhones, wrote NPD analyst Ben Arnold. Without those jacks, owners will be forced to use either Lightning or Bluetooth connections for external audio.