Digital audio is now established among consumers while the use of Internet-connected devices, like in-car devices, smartphones, tablets and connected TVs, is increasing and boosting the digital market.

That’s according to the findings of a new study from TargetSpot, called the “2012 Digital Audio Benchmark and Trend Study.” The survey sample included 1,000 adults who listen to Internet radio between at least once a month up to daily listening, according to Parks Associates, which fielded the poll.

Internet radio listenership has reached 42% of adult households in the U.S. that have a broadband connection, an increase of 8% compared to 2011. The purchasing power of that audience is also rising, according to the findings, with 22% having a household income of $100,000, a 29% increase over 2011.

TargetSpot is a digital audio advertising network, working with name brand advertisers and streaming partners like CBS Radio, ABC Radio News and Entercom as well as Slacker, Live365 and Grooveshark.

Digital audio listeners are also highly engaged: 80% listen from one hour to three hours per day and 40% listen to between one to two hours per session. Seventy-five percent of listeners change stations on the same Internet radio service at least once a day, andnearly two-thirds change to different Internet radio websites at least once a day, according to this year’s findings.

Interactive Advertising Bureau VP Michael Theodore says the study provides insight into consumers’ interaction with a medium that is becoming increasingly important to marketers, adding that digital audio listeners are highly engaged, connected at home, in the gym and the car “and they respond to advertising.” Fifty-eight percent of listeners recalled having seen or heard an Internet radio ad within the last 30 days compared to 52 percent in 2011, an 11% increase.

Consumers are spending more time listening across multiple devices. Compared to last year, 48% of digital audio listeners spend more time listening on their tablets, 44% spend more time listening on computers and 38% spend more time listening on mobile phones.

The use of connected TVs and in-car Internet radio players is on the rise and are market segments to watch moving forward, according to TargetSpot. More than one-third of Internet radio listeners regularly tune in to digital audio on a connected TV and 14% listen on an in-car Internet radio player.

Of those that have in-car Internet radio access, more than half (54%) use an Internet radio player that is built-in to the dash and one-third use Internet audio apps on portable Internet radio devices that they connect to the car. Additionally, 15% manually connect a smartphone or tablet into the car’s device outlet, according to the findings.

The study found 86% of Internet radio listeners do not pay a fee for access to premium digital audio content, in essence opting-in to receive ads on free ad-supported digital audio services.