By Jeffrey Dastin
SAN FRANCISCO - Amazon.com Inc is dominating the nascent market for voice-controlled speakers, research firm eMarketer said on Monday.

The e-commerce giant's Amazon Echo and Echo Dot devices will claim a 70.6 percent share of the U.S. market this year, the study found. The speakers feature Alexa, Amazon's voice-controlled aide, which users can tell to play music, order an Uber or turn on the house lights.

That puts it far ahead of Alphabet Inc's Google Home, a similar gadget that has a 23.8 percent share, and less successful offerings from other tech companies.

The number of active U.S. users will more than double for the devices this year, to 35.6 million, eMarketer said.

The report underscores Amazon's progress in making Alexa and its speech-recognition technology an integral part of customers' lives. More users means more data that can improve Alexa's understanding and could make it a top platform for voice, like Windows is for desktop.

Amazon does not disclose Echo sales figures but has said it had trouble keeping the product in stock. Device sales and extra revenue from shoppers placing orders via Alexa could generate $10 billion for Amazon by 2020, RBC Capital Markets analyst Mark Mahaney said in a recent note. And that does not include potential revenue from others using Alexa as a platform.

Google's share is expected to grow, though. Tests by analysts have shown the technology underpinning the Google Home to match or be superior to competitors. A survey by Mahaney found the device's brand awareness in the United States already equaled 80 percent of Alexa's, despite being on the market for fewer months.

The statistics from eMarketer focused on speakers and left out other virtual assistants: notably, Apple Inc's Siri and Microsoft Corp's Cortana. More than 60 million in the United States will use virtual assistants at least once monthly in 2017, the report said. That's over a quarter of U.S. smartphone users.