Spending on mobile advertising is soaring, but interestingly — considering the amount of time smartphone users hang on their devices — it could be much higher.

While mobile spending is expected to leap 83 percent in 2014, many industry analysts see even more room for growth.

That’s the conclusion of a new Wall Street Journal post on this very topic.

“After less than a decade of existence, smartphones and tablets this year will draw more money from advertisers than the centuries-old newspaper industry or the nearly century-old radio sector, a sign of just how rapidly technology is transforming media habits,” says author Steven Perlberg.

However, here’s the caveat: “But given how much time Americans spend on their devices, mobile-ad spending could be much higher, an indication that marketers remain uncertain about the medium’s effectiveness.”

That nearly $18 billion in mobile spending is a sign that smartphones and tablets are where advertisers need to be.

“As more eyeballs are going there in larger numbers, the dollars are starting to follow,” said Cathy Boyle, an eMarketer mobile analyst.

“Still, the imbalance remains stark: American adults now spend almost a quarter of their media time on mobile devices, eMarketer estimates, yet this year’s spending growth will raise mobile’s share of the ad market to only 9.8 percent,” according to the post. “By contrast, American adults spend only 2 percent of their media time reading newspapers but ad spending for the sector hangs just under 10 percent of the overall market, eMarketer estimates.”

Questions do remain about the effectiveness of mobile advertising persist.

eMarketer polled a dozen marketers and digital ad experts, who gave the effectiveness of mobile display ads a “B-.” Other mobile ad formats fared better, like location-targeted ads, which received an “A-.”

“The location capabilities inherent in mobile are a big factor driving a lot of ad revenue into the mobile space,” Ms. Steele said. Marketers are excited about the idea of being able to serve ads on the smartphones of shoppers within the radius of a particular store, for example.

As soon as the measurement tools for mobile are more developed and reliable, industry experts expect marketers will become increasingly comfortable with shifting more money to mobile.