Just how popular are smartphones and tablet computers these days? Popular enough that according to a new study, print books could soon tread into the same decline road that CDs and other physical audio form had taken in the past years.

While MP3 and other digital audio files, which were easily downloadable and transferrable, spelled the near-extinction of music off-the-shelves, the introduction of smartphones and tablets in the past decade flagged brewing troubles for book and other print publishers the world over.

In the lucrative North American publishing market, the March report of the Association of American Publishers (AAP) showed that in the current year eBook sales further gained traction during the first three months, chalking up total quarterly sales of $US282.3 million in the period.

The latest results, which was first reported by publishing guide website GalleyCat Friday last week, showed that eBook turnovers netted much more as compared to the Q1 sales that digital books garnered in the corresponding period in 2011, placed by AAP at $US220.4 million.

Sales of paperbacks, on the other hand, plummeted this year, according to data provided by more than 1000 U.S. publications, accumulating only a March end-sale of $US229.6 million as against to its 2010 performance that saw American readers paying a total of $US335 million for their preferred book titles early last year.

Tech news site Mashable noted that that figures pointed to the growing dominance of ereading habits among Americans and other book lovers around the world.

The more than 28 percent surge in eBook purchases as of March this year only proved that ereading devices are on the rise, Mashable said on Sunday, owing to the proliferation of the mobile device, which can come as standalone such as the first Kindler edition issued by Amazon and its close competitors that followed the release of the hit mobile reading gadget.

But what accelerated the rise of eBook was the ereading functions included on the now ubiquitous smartphones and tablets, which an earlier report have credited as foremost responsible for youngsters to pick up early reading habits.

The assertion makes sense, experts said as hundreds of millions of iPhones, iPads and other Android-powered gadgets have been sold since the mobile products became hit among consumers as early as 2007.

And it is safe to assume that a great majority of smartphone and tablet owners from around the world belong to the adolescent and young adult age brackets, which they account for most of the world's mobile computing activities.

Such activities include digital reading and digital purchases of books if the U.S. sales of eBooks in the segment were of any indication.

According to the AAP report, young adult and children eBooks in the first quarter of 2012 accounted for a total sale of more than $US64 million, its climb reaching a dizzying level of 233 percent in the first three moths of the current year alone.

Analysts predicted that hundreds of millions more of smartphones and tablets will be sold this year before the year ends, leaving an impression that eBook sales would eventually top sales of hardcovers not only in the current year but also in the succeeding years.

That global trend was also felt in Australia as early as 2010, when book retailers started closing shop in wholesale numbers, inarguably succumbing to the steady onslaught of the exploding eBook market segment.