The Australian Institute of Health and Welfare report found teenagers aged 15 to 19 experienced the highest rate of sexual assault of any age group, with females much more likely to be victims than males.

Males aged 15 to 19 had the highest offender rate of any age group.

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Kate Wright, the chief executive officer of Centre Against Sexual Assault Central Victoria, believed the high prevalence of sexual assault among teenagers was largely an issue of consent and reflected the drivers that underpinned other gendered violence, such as family violence.

Young people are also exposed to pornography more, with some 90 per sent of boys and 60 per cent of girls having seen it online.

Ms Wright said pornography offered an unrealistic view of sex and consensual relationships.

"We're not having the discussions we need to have with young people about consent, respectful relationships, and how to respond or how to talk when things don't feel right," she said.

"And to do that, we need to increase the conversations that are occurring within the community, within schools, and with a range of organisations that intersect with children and young people."

Ms Wright said parents and carers also needed to be prepared to have these uncomfortable but important conversations with their children.

She said CASA was working with young people in the Macedon Ranges on a consent project, and was looking at developing a group for young people that would run over several weeks.

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The AIHW report revealed the rates of sexual assault victimisation for people aged 15 and over rose by 30 per cent from 2010 to 2018, although it was not clear if this was due to an increased incidence of sexual assault, more people reporting the issue to police, or more people reporting historical assaults.

Ms Wright said the report's data reflected local prevalence trends.

"It's great that there is a focus on sexual assault by the Australian Institute of Health and Welfare... because we're not seeing the prevalence dropping, which indicates we need to be doing more work in the prevention domain for sexual assault," Ms Wright said.

Crime Statistics Agency data shows sexual offence rates are higher in most parts of central Victoria than the state average, and CASA Central Victoria sees more than 1100 people each year who have been the victim of sexual offences.

"We are seeing a lot of work in that space around gender equality, both at a state and federal level, but we have to ask why we aren't seeing that reflected... in the harm to women and children," Ms Wright said.

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The National Community Attitudes towards Violence against Women survey in 2017, cited in the report, found 11 per cent of people believed a woman was probably lying about sexual assault if she did not report it immediately, 1 in five were unaware rape within marriage was against the law, and 33 per cent thought rape resulted from men being unable to control their need for sex.

The report noted sexual assault's impacts went beyond the physical, with survivors reporting anxiety and fear, difficulties sleeping, changes to their normal routine, and disruptions to their ability to work.

Ms Wright said people who had suffered historical sexual abuse had lived with their trauma for decades in some cases.

"They feel shame, they've lived with a secret," she said.

"For some people, when they've tried to tell people what's happened, they've been blamed.

"And the predominant conversation in society for women is how to avoid being raped... rather than the message being, 'You shouldn't rape'."

If you or someone you know has experienced sexual assault, contact CASA Central Victoria on 5441 0430, the Sexual Assault Crisis Line on 1800 806 292, or 1800RESPECT on 1800 737 732.

In an emergency, call triple zero.