A recent NPR study confirmed that what many have surmised for years is true: Public radio shows sent through the Public Radio Satellite System vary widely in loudness.

An NPR working group that has been studying the issue found that roughly 53 percent of the content they examined deviated from standards PRSS recommends to keep volumes consistent. The group is looking at creating new best practices and implementing a software fix that could cheaply curb the problem.

“It’s a big issue in the system,” said Paxton Durham, chief engineer at Virginia’s WVTF-FM and Radio IQ. “I’ve been here 24 years, and as long as I can remember there’s always been a problem.”

Research cited by NPR found that anything more than a 4-decibel change in volume can prompt listeners to adjust volume levels. A change of more than 6 decibels can cause them to change to another station.

“If we are not consistent across the system, it’s not going to be a good experience for the listeners,” said Chris Nelson, NPR’s director of digital strategy, during the NPR board’s May meeting.

In a presentation to the board’s distribution and interconnection committee, Nelson described how a group of NPR engineering staff analyzed the loudness of more than 6,000 files, including NPR newsmagazines and underwriting messages; programs from American Public Media and Public Radio International; and additional PRSS content.

“Basically, if it was available, we tested it,” Nelson said. And engineers were surprised at the degree of fluctuation in the sound levels of PRSS content.

“We have a real issue here,” Nelson said.

A mashup of PRSS content presented by Nelson, along with a visual representation of the sound spectrum, backed up his point. Radiolab and On the Media, for example, were significantly louder that Marketplace Tech Report and This American Life. Some of the quietest content was from two syndicated music services, Classical 24 and PubJazz.

The discrepancies were also discussed during the annual Public Radio Engineering Conference in March. Most engineers knew that PRSS volumes were inconsistent but had underestimated the extent of the problem, said Shane Toven, director of engineering for Wyoming Public Media, who attended the conference.

“It is something that needs to be addressed,” Toven said. “It’s all over the map.”

Engineers at the conference seemed to support solutions that would not apply punitive measures such as fines, according to Toven.

NPR’s team examining the problem plans to create a new target level for PRSS content based on the use of loudness meters. It will also work on creating a list of affordable tools producers can acquire to measure volume.

Most producers track volume with peak meters — colored bars that rise and fall with noise levels. Loudness meters, however, measure volumes numerically, which NPR’s engineers said increases accuracy. The meters cost as little as $100 and as much as thousands of dollars, Nelson said.