NEW YORK: Driven by a need to prop up revenues, several leading cable TV networks have taken to squeezing more ads into programming – even by speeding up a show's dialogue – but critics say the practice is misguided.

TBS, for example, aired The Wizard of Oz last November with voices that were slightly speeded up and it also employed the technique with reruns of the sitcom Seinfeld and other shows, the Wall Street Journal reported.

Its sister network TNT and Viacom's TV Land also have done the same with reruns of various shows.

Industry insiders have conceded that the purpose is to achieve a higher volume of ads as cable networks deal with declining ratings while meeting audience guarantees made to advertisers.

"It is a way to keep the revenue from going down as much as the ratings," said an unnamed senior executive at a major cable network. "The only way we can do it is to double down and stretch the unit load a little more."

However, some brand advertisers and agencies have expressed concern that the practice could prove counter-productive.

They fear it could reduce the effectiveness of their spots and encourage more TV viewers to switch to ad-free streaming services, such as Netflix and Amazon.

"It is important for us to consider the effect this is having on the viewer experience," said Jackie Kulesza, executive vp and director of video at Starcom USA. "We want to ensure our message is seen by receptive viewers."

Echoing her concerns, Chris Geraci, Omnicom Media Group's president of national broadcast, said: "They are trying to deal with a problem in a way that is making the problem bigger."

"It has gotten completely out of control," agreed an unnamed head of distribution at a major TV studio. "I'm concerned when you look at the performance being diminished and hurt by their running the shows that way."

Data sourced from Wall Street Journal; additional content by Warc staff