The sense of Emory University, a small, close-knit private school, as a protected environment has been shaken after an unusual number of sexual assaults were reported to campus police.

This fall, seven rapes, including at least one from 2011, were reported at the school. The incidents, most of which happened this semester, were revealed during counseling sessions, Emory officials said. The reporting was anonymous and all involved acquaintances.

Federal law requires that counselors alert campus police of such incidents, but no victims filed charges and no investigations were initiated.

Because of the concentration of young people in one place, many of them out from under parental oversight for the first time, sexual assault on college campuses is a huge problem. National statistics show 70 percent of sexual assault victims are under 25 and one in four sexual assaults occurs on college campuses.

The United States Student Association reports that about 13 percent of college women report being stalked during an academic year and one in five are sexually assaulted.

The reports at Emory prompted a decisive show of solidarity with assault victims during the school’s annual anti-crime “Take Back the Night” assembly last week and triggered widespread concern about the best way to reduce sexual violence on college campuses.

“The thing that surprised me the most was how prevalent the issue is, even at Emory,” said Caleb Peng, an Emory senior studying psychology, who created a YouTube video focusing on sexual violence during an internship with the school’s Office of Health Promotion.

The clip, and a follow-up, which have been viewed thousands of times, use short interviews with dozens of students and emphasize the extraordinary efforts women must expend to stay safe.

“I know through statistics,” said Peng, “but it’s another thing to see it in person.”

The “Take Back the Night” activities included a “Speak Out” demonstration at Emory, during which statements from anonymous rape survivors were read out loud. Lauren Bernstein, coordinator of the Respect program, which addresses sexual violence on campus, said the turnout of 250 demonstrates a groundswell in the movement to combat rape.

“There’s a lot going on independent of any media coverage,” Bernstein said. “Attitudes are changing.”

The spike in reported assaults in the past few months corresponds to a trend reported by several college officials and public safety professionals: Sexual assaults occur more often in the early part of the first semester.

This is partly because inexperienced freshmen are thrust into a new environment, they say.

“They’re out there meeting people, giving their trust, instead of making people earn their trust,” said University of Georgia Police Chief Jimmy Williamson, whose school reported five rapes last year.

Most assaults on campus are by acquaintances, he said, and new students haven’t had time to assess their new friends.

“We make ourselves vulnerable to other people who have the wrong intention,” Williamson said.

Alcohol, involved in 90 percent of all rapes on college campuses, is also a factor, he said. In the fall, students participate in the autumn round of celebrations, including football parties, Halloween and fraternity and sorority rush, and partying brings drinking.

“If you’re drunk in a party with people you don’t know, yes, you’re more vulnerable,” said Jill Lee-Barber, director of psychological and health services at Georgia State University. Four sexual assaults were reported at Georgia State last year.

But police, parents and fellow students should refrain from second-guessing victims, she said.

“The onus of responsibility for violating somebody is not on the person who was violated,” said Lee-Barber.

Acquaintance rape is a slippery subject, and students are frequently unaware of what constitutes consent. This is why Georgia State requires each new freshman class to view a 90-minute show where an actor and an actress re-enact social situations, using audience interaction and improvisational comedy to draw attention to the ethical issues in sexual relationships — and the strategies of predators.

Such a proactive approach is a way to deal with what has become a hot-button issue. Nationally, a growing number of universities, including Southern Methodist University in Texas and Xavier University in Ohio, have been criticized for the way they handle reports of sexual assaults.

Boston University is carrying out recommendations from a task force that called for the school to address systemic issues of assault and alcohol abuse on campus and improve oversight of the men’s ice hockey team after two players were accused of assault last spring.

Amherst College formed a committee to make recommendations on how to enhance “sexual respect” on campus after dozens of victims came forward publicly to complain how the school worked against them after they reported attacks.

While the number of reported incidents may shock people, seeing those numbers increase is actually a good thing, said Michelle Issadore, executive director of the School and College Organization for Prevention Educators, whose members deal with sexual abuse, mental health and other issues.

“People report only when they feel safe and believe they will be supported,” Issadore said. “It is not that the actual number of cases are increasing so much as that it has been under-reported for so long that we are only starting to get a more accurate report of what’s happening.”