Crediting “sustained growth” of business in the U.S. market, Targetspot revenue grew 31.5% to $4.4 million during the first three months of the year. The Audio Valley Group, its Brussels-based parent company, says the number reflects a “boom in digital radio and a swing in advertising budgets” with growth “being confirmed” in the U.S. The vast majority of Targetspot’s revenue comes out of the U.S. where during the quarter sales of advertising on streaming radio and podcasts totaled $3.3 million, a 27% increase compared to a year ago.

“To date, the Targetspot network monetizes several thousand digital radio stations and aggregates one of the main global digital audiences,” the company told investors last month in its annual report. “This growth reflects the relevance of an offer that, thanks to the technology of a comprehensive monetization management platform, allows both internet radio and FM radio [to] have a digital audience to generate new revenue.”

TargetSpot has taken several steps during the past year to strengthen its ad-selling capabilities. Earlier this month it cited the “tremendous growth” in digital audio advertising as a reason for opening a new office in Atlanta targeting the Southeast. Internationally, Targetspot expanded into the U.K. this month as it opened a new office in London. That brought the number of new offices opened by the company during the past year to five.

TargetSpot is also expanding its sights beyond streaming radio to podcasting. It launched a podcast ad marketplace in December connecting podcast publishers with advertisers throughout North America and Europe. Advertisers will be able to buy pre-roll and instream audio through programmatic connections to major demand-side platforms and through direct buys. In its annual report, Audio Valley said the goal of the Podcast Marketplace is to give ad buyers “a clear and well-segmented” buying option. “The podcast market is promising with initiatives coming from many new publishers like daily newspapers and magazines,” it said.

With offices already in the U.S., Belgium and elsewhere, Targetspot also said it increasingly sees an international sales network as a key to growing digital audio revenue. That led it to launch a European sales network last year and open offices in Spain, the Netherlands and Germany.