Over the past year, ear-worn devices have emerged as the most promising growth category within the broader wearables market. Market researcher IDC has been raising its forecasts for wearables all year, and now expects 2019 wearables volumes to be higher than even those boosted estimates. IDC initially thought wearable device shipments would hit 198.5 million this year, then increased its estimate to 222.9 million over the summer. In its latest forecast, released this week as the year winds down, IDC is now expecting wearables volumes to hit 305.2 million -- over 50% more than its initial estimate.

Here's what's happening in the wearables market.

Woman wearing AirPods and Apple Watch using an iPhone

Image source: Apple.

The wearables tables have turned

The 305.2 million units that should ship this year represent growth of 71% compared to the 178 million units shipped in 2018. A lot has changed over the past nine months, mostly within the hearables market that all the major tech companies are jumping into in an effort to counter Apple's (NASDAQ:AAPL) dominance.

At the onset of 2019, smartwatches were expected to dominate unit volumes with a 45.6% share, with earwear accounting for just 27.4% of the market. Fast-forward to today, and the tables have turned: Earwear should grab 45.7% of the market, and smartwatches will have a 22.7% market share.

Product Category

2019 Estimated Shipments

2019 Estimated Market Share

Earwear

139.4 million

45.7%

Smartwatches

69.3 million

22.7%

Wristbands

68.2 million

22.4%

Other

28.2 million

9.2%

Total

305.2 million

100%

Data source: IDC.

The stark discrepancy between the forecasts demonstrates how rapidly the wearables market -- and consumer preferences -- are evolving. Apple has launched a slew of hearables throughout 2019, including AirPods 2, Powerbeats Pro, Solo Pro, and AirPods Pro. In fact, Apple effectively threw off IDC's March forecast by announcing AirPods 2 just days later, jump-starting demand.

The Mac maker also continues to sell its Apple Watch Series 3, which received a price cut after the Series 5 launched in September.

"Underpinning the growth in the wearables market has been a drastic reduction in average selling prices," IDC's Jitesh Ubrani said in a statement. "While companies such as Xiaomi have focused on reducing costs by commoditization, market leaders like Apple that typically focus on the premium segment are also playing a crucial role in lowering prices."

Alphabet subsidiary Google is trying to acquire Fitbit to get a better foothold in the wearables market, following years of meandering along with Wear OS. Fitbit was the No. 5 player in the wearables market in the third quarter, according to separate estimates from IDC, but the smaller wearable tech company's shipments were flat.

The wearables market is evolving at a breakneck pace

Going forward, IDC estimates that the wearables market will soar to 489.1 million units in 2023, representing a compound annual growth rate (CAGR) of 22.4%. Earwear is expected to represent 273.7 million of those units that year, with smartwatch shipments forecast at 109.2 million.

However, investors should approach those projections cautiously. The wearables landscape shifted so rapidly that earwear easily blew out IDC's initial forecast (139.4 million compared to 54.4 million) in just nine months, so you can only imagine how much things will change over the next four years.