According to data from Triton Digital, an exchange for audio advertising on programmatic, there are a lot of podcast listeners in the United States of America. Around 24% of the North American population listens to a podcast regularly. This number is growing since 10 years ago when this percentage was only 9%.
The audio advertising is already available in some SSP´s like Appnexus, despite the fact that IAB still didn’t establish any guidelines for this format.
There is inventory ready to be monetized, but Google, the main exchange on programmatic, shown lack of interest until now, being Appnexus and The Trade Desk the main pushers of audio.