The top sports radio station in June, KFXX-AM, ranked 21st out of the market’s 35 stations, according to Nielsen. Its biggest competitor, KXTG-AM, ranked 22nd. A third, KPOJ-AM, was 25th, just ahead of a jazz station.Yet the Goldberg Jones law firm in Seattle advertises on all three sports stations.Rick Jones co-founded the firm in 1996 and helped it establish a niche by providing divorce services for men. At first “the big game was yellow pages” when it came to marketing, he said. Soon, though, the firm turned to radio, which was appealing for both its price and its reach.

More than 20 years later, sports radio’s audience remains largely the same. Entercom, the parent company of KFXX, says that the roughly 40 sports radio stations it owns average 11 million listeners per week. Of that audience, 71 percent is male. Ads for Jones’ law firm on KFXX are often bookended by commercials for a chain of testosterone-therapy clinics and for a shaving supply company called Harry’s.

 “Given the male skew for sports radio, those advertisers may find the format suitable,” says Jeff Sottolano, senior vice president of radio and Radio.com programming from Entercom. 

Traug Keller, senior vice president in charge of ESPN Audio and Talent, noted that between 80 and 90 percent of the audience listening to ESPN Radio’s more than 400 affiliates throughout the United States is male. Combined with ESPN’s satellite radio and streaming audio stations, Mr. Keller said ESPN radio reaches one in every five sports-radio listeners ages 13 and older in the United States, and accounts for nearly half of all sports radio listening nationwide.

When compared with the rest of radio — not to mention streaming audio and podcasts — sports radio is still a niche, but one of increasing interest for advertisers. John Fitzgerald, vice president of ESPN’s multimedia sales for audio and ESPN Deportes, said that ESPN Radio had about 30 advertisers when he began working with the company 20 years ago. It has more than 300 now, and the field of advertisers has diversified.

While ESPN Radio’s listeners are largely male, Mr. Fitzgerald said they vary in race and ethnicity. Fitzgerald also noted that ESPN Radio also has a high number of listeners making between $150,000 to $1 million a year, while Entercom’s Mr. Sottolano said Entercom sports stations and the company’s CBS Radio Network affiliates tend to skew toward the college-educated and households making more than $75,000.They’re also more engaged than the average radio listener.