The veteran comedy star Bill Cosby struck a defiant pose and lapped up standing ovations at one of his live shows in America this weekend as he faced down growing allegations of rape and sexual assault made publicly by more than a dozen women.

Raising a clenched fist, 77-year-old Cosby was cheered at his standup comedy show in Melbourne, Florida, on Friday night, where die-hard fans turned up in droves to support the enduring television superstar known by the affectionate moniker of “America’s Dad”.

But by Saturday a 13th woman, Kristina Ruehli, had identified herself and yet more details emerged from others accusing him of sexual aggression and rape from the 1960s up to 2005. The number of women who have, either anonymously or openly, now accused Cosby has risen to 17, with an unusually large number talking on camera. So many victims of alleged sexual assault, from many walks of life, are now going public to talk unashamedly about their experiences in America that experts are hailing it as the most significant cultural shift against rape in a generation.

Ruehli, 71, this weekend became the latest woman to identify herself in connection with alleged sexual aggression by Cosby. She said he tried to force her into oral sex in 1965 when she was a 22-year-old secretary at his talent agency.

He has never been charged with a crime and settled just one lawsuit in 2005. Ruehli said: “I don’t need money or aggravation. I’m very wealthy, so I have nothing to gain. But I wanted to come forward to tell the truth to back up other people.”

Despite 11 women going public for the first time in the last 10 days, Cosby has refused to comment. In an interview with a Florida newspaper on Friday, he said: “I know many people are tired of me not saying anything, but a guy does not have to answer to innuendo.”

His legal team has dismissed the women’s claims as, variously, old and discredited, preposterous, illogical, fantastical or “absolutely false”.

However, a planned television comeback for Cosby has stalled and re-runs of his hit 80s sitcom have been cancelled. The Cosby Show made him an international celebrity in the 80s and a role model for many African-Americans, with its depiction of a successful middle-class family.

Shows in six states on Cosby’s current tour were cancelled this weekend, though more than 25 shows remain on his schedule.

Outside Melbourne’s King Center on Friday night, it was reported that opinions were mixed. “I bet if he gave every one of them $2m they’d never say a word again. They just want the money,” said Marc Linden, a retired teacher.

Hairdresser Tamara Allredge said Cosby was innocent until proven guilty, but that the accusers had the right to be listened to. “The backlash against these women has really bothered me,” she said.

One of the most striking aspects of the current scandal is how many women have spoken publicly. Recent rows in the US about rape in the military and sexual violence on college campuses have also been marked by women going public.

“I’ve been in this field for 30 years and many more people are coming forward now than in the past to identify themselves and talk in detail and without shame about sexual assault. It’s the most dramatic change in the anti-rape movement since the 70s,” Dr Connie Best, a clinical psychologist at the US National Crime Victims’ Research and Treatment Center in South Carolina, told the Observer.

In the scandals over Jimmy Savile and other personalities in Britain, accusations have emerged but many victims have chosen to remain anonymous.

Mary Haviland, executive director of the New York City Alliance Against Sexual Assault, said: “America has a long history of social movements, but especially highly visible ones in modern times such as civil rights, gay pride, the women’s movement and immigration rights. There’s a new attitude emerging here towards speaking out courageously and publicly about sexual violence. It’s a very positive development.”

In the Oscar-nominated documentary The Invisible War in 2012, more than a dozen female US troops went public about rape in the military, prompting reforms. The film’s producer, Amy Ziering, said it had “smashed a barrier”.

Across US campuses, too, students are not just protesting about rape en masse, but are individually identifying themselves as victims. Emma Sulkowicz is carrying a mattress with her everywhere on the campus of elite Columbia University in New York to protest against official inaction over a former boyfriend she says raped her.

Earlier this year five women at the University of Connecticut held a press conference to announce a settlement over sexual assault. One was an ice hockey player who said she was thrown off the team after accusing a male player of rape.

Fewer women are being named so far in a recent flurry of rape allegations involving sportsmen, but several are publicly accusing professional American footballers of domestic violence.

A Baltimore-based civil rights lawyer, Susan Burke, said: “I’m elated that it’s becoming more common for victims to report their experiences openly. It’s incredibly important because it reduces the stigma and I hope you’ll begin to see the end of a society that protects rapists.”

@joannawalters13