Ennals said going digital was a case of "when not if", and claimed the 2015 target switchover date, dependent on more than 50% of listening being on digital by the end of 2013, was "challenging but achievable".
Tabor was responding to yesterday's report by the Consumer Expert Group that warned that the target digital radio switchover date of 2015 was "far too early".
The previous Labour government's Digital Britain report in 2009 had earmarked 2015 as the target date for switchover, when all national and large regional and local stations would become digital-only.
It also sought to tackle internet piracy and set a 2015 target for digital radio switchover.
The industry and government is targeting a 2015 radio switchover date, but only if digital radio accounts for more than 50% of all listening by the end of 2013.
"I believe we're at a time when a date [for switchover] could be set as a target, not as commitment," he told MediaGuardian.co.uk after the speech.
The executive in charge of digital radio switchover today distanced himself from the 2015 target date set two years ago and apologised for any confusion it may have caused among listeners.
The government and industry has set a tentative target of 2015 for digital radio switchover, when all the national and big regional and local stations will only be available in digital.
The RNIB head of broadcasting and talking images, Leen Petre, said: "We believe the switchover to digital in 2008 is an ideal opportunity to increase the target for audio described programmes.
