BADA BING!

“The Sopranos” hit a record-shattering high note for Home Box Office on Sunday, as the pay-cable series’ long-deferred fourth-season premiere dominated the ratings, while striking fear into the hearts of the major networks.

Estimates from Nielsen Media Research indicate that 13.4 million people were watching one of HBO’s channels while “The Sopranos” aired--the pay channel’s biggest audience ever, eclipsing the show’s 2001 premiere by 2 million viewers.

That audience would have placed “Sopranos” sixth among all prime-time programs last week--a stunning figure given that HBO is received by roughly a third of the 106.7 million homes with television in the U.S. The program easily won its time period, beating all the broadcast networks, which have yet to launch their new seasons.

Tune-in for “The Sopranos” clearly caught the attention of network officials, who privately said that it exceeded their projections--a sentiment echoed by HBO.

“This was above what most bright and logical minds thought we would do,” said Dave Baldwin, HBO’s executive vice president of program planning. “This was a big number.”

The question now is how well the series will hold up over its 13-week run against original competition--having previously played in the spring and summer, when it faced more reruns.

The series will continue the next 12 weeks, facing such events as the Emmy Awards this Sunday as well as the second--and if necessary seventh--game of the World Series. (“Sopranos” isn’t an Emmy contender this season because it wasn’t shown during the eligibility period.)

The third season of “The Sopranos” did drop after its premiere, averaging about 9 million viewers. As The Times reported recently, audience estimates for the program are imprecise, since Nielsen does not break out HBO programs individually, instead lumping together the number of people watching any of its channels at a given moment.

Still, HBO runs each episode five times per week, and Baldwin noted that the channel pays more attention to the overall percentage of subscribers that watch, which topped 30% during the third season. Because HBO doesn’t sell advertising, it measures success by subscriber satisfaction, as reflected by who signs up for or cancels the service.

“Sopranos” set the bar almost impossibly high for the series that followed, the Emmy-nominated Larry David comedy “Curb Your Enthusiasm.” Almost 60% of HBO viewers tuned out once “The Sopranos” ended.