I’ve been keeping my ear out for the song of the summer. It’s gotta be a song with that hook, the beat, and becomes an earworm before you know it. Though jamming to Lil Nas X or the Jonas Brothers is not just a summer activity. U.S. adults spend more time listening to digital audio than browsing on social media. With 204 million digital audio listeners in the U.S. or nearly 2/3 of all digital media consumers, digital audio is the second most popular digital activity (based on time spent) for U.S. adults (behind the video). People have even started to spend more time on digital audio than on AM and FM radio.

This is leading to more media investment. The latest IAB Internet advertising and revenue report (prepared by PricewaterhouseCoopers) stated that digital audio advertising revenue reached $2.3 billion in 2018 — a 22.9% full-year increase over 2017’s revenue of $1.8 billion.

Digital audio includes not just streaming music, but live talk radio and sports, as well as podcasts. In fact, podcasts are a quickly growing audio format in terms of listenership. Survey research from Infinite Dial shows that 70% of respondents ages 12 and older are familiar with podcasts. But have they binged on Wondery’s Dirty John in a week?

Audio is personal

Digital audio is a naturally mobile (and personal) channel. Most people consume it on their headphones. But they also may be in their car. Or they’ll have the dial turned up past 11 on their smart speaker in their house. Anyone can consume audio while on the move and its part of so many stages of your day – the moment you wake up, during your commute, at work, at the gym, or when you’re cooking. It goes on and on.

People have always been listening to something – music, live games, talk shows, etc. Audio is consumed actively or passively. It’s the ultimate multitasking media channel – you can walk or drive while listening at the same time. Try reading this piece or binging on video while crossing an intersection.

Listen to the Money

Audio ads offer deep engagement. They are served on an already a personal medium. They cost relatively less to produce than other ad units (it’s all writing, voice, and sound). You get a high share of voice –listeners only hear one ad at a time, which are not easily skippable (would you pause your workout just to skip an audio ad?).

These qualities lead to efficiency and effectiveness. Nielsen Media Lab says audio ads have a 24% higher recall rate than traditional display ads. Even more, the audience data produced with audio creates good addressability, where the marketer can utilize their understanding of users’ locations, interests, preferred genres and more to target with unique messages.

Audio Ad Automation

Programmatic buying is an emerging factor, creating more automation in the buying, selling, and fulfillment of audio ads. Plenty of audio content publishers sell direct, but there is a rising trend to make more inventory available through programmatic systems. Spotify claimed that programmatic sales are now over 1/4 of its ad revenue. Other programmatic audio suppliers now include Pandora, as well as marketplaces like TargetSpot, Triton Digital, and TuneIn, with millions of audio impressions daily.

Don’t Audio Alone

Audio (much like any emerging medium or tactic) should be utilized within multi-faceted campaigns that blend together with other formats such as display, video, search and social. Audio should not be activated by itself, on tools outside of your team’s typical workflow. Otherwise, it causes extra work connecting it with the other related parts of your campaign. When media teams are using digital audio ad buying tactics with their overall digital strategy, they are maximizing a full arsenal of tools to operate high-performing campaigns.

Digital audio is worth consideration for shifting budgets. It is personal. It is growing in popularity. And the rise in programmatic buying in audio will increase the volume of transactions through the channel as campaigns are faster to execute.

And for the song of the summer, while Ed Sheeran and Bieber may win out singing I Don’t Care, you should care and give digital audio a second listen as you plan digital campaigns.

Read more: Voice Assistants Land Brands in Uncharted Creative Territory