, Inc. (AMZN) has sold approximately 8.2 million Echo devices, its voice assistant speakers, so far, according to research firm Consumer Intelligence Research Partners (CIRP). This past quarter was especially good – CIRP estimates that the Seattle-based company sold 3.1 million Alexa devices during that time period. 

The increase in sales was accompanied by a rise in awareness about Amazon's voice assistants. Consumer awareness of Amazon Echo speakers was 82% by the end of last year, up from 47% as of the same time in 2015. Echo speakers were first released in December 2014 and were a surprise holiday hit that season. They essentially kickstarted the voice-activated smart assistant industry. (See also: Alexa, Who Won CES This Year?)

A number of major technology players have released their own voice assistants. For example, Alphabet Inc. subsidiary Google (GOOG) released Google Home, its take on the voice assistant, last year. According to analytics firm VoiceLabs, Google's device has sold between 400,000 and 500,000 units since launch. (See also: How Does Google Home Compare With Alexa?)

In a report on trends that will shape the voice speaker industry, VoiceLabs also predicted that a total of 24.5 million units of voice-activated assistants will be shipped by the end of this year. However, based on the report's findings, it would seem that voice assistants have problems with stickiness. For example, only 31% of Alexa's skills have more than one review. "This indicates that many of Alexa's voice applications are 'Zombie Skills': they are accessible but not heavily used or appreciated," the report's authors write. 

That said, a bump in sales comes with several advantages for Amazon. For starters, it enables the company to mop up data about consumer tastes and shopping habits. Such data could prove to be invaluable for the e-commerce company to extend its reach into consumer homes as well as minimize the number of steps required to order a product from its website. (See also: Amazon Set to Disrupt Auto Parts Industry.)

Then there is the prospect of additional revenue from paid search on its platform. Based on statements at a recent media conference​ by Seth Dallaire, vice president of global ad sales at Amazon Media Group, the company may begin paid search queries sooner rather than later. At the conference, he outlined a number of examples in which Amazon's search functionality (which, according to some estimates, is favored over Google for product searches) could be useful to consumer product companies. For example, Amazon partnered with Campbell Soup Company (CPB) to develop a branded skillset for Alexa that enables users to search for recipes using Campbell's products. (See also: Will Amazon Get Into the Online Ads Business Next?)