In a submission to a senate inquiry, Advocacy for Inclusion general manager Christina Ryan said existing efforts had failed to hear from the very people it had hoped to help.

"Violence in institutional settings is a hidden issue and the fact that such an inquiry has been unable to reach out to the people it seeks to inquire about highlights this very problem," she said.

The senate inquiry into violence, abuse and neglect against people with disability in institutional and residential setting was announced in February and is due to report in September.

The inquiry was moved by the Greens after a Fairfax Media/ABC investigation revealed alleged abuse of disabled people at a range of institutions and homes, including with the disability provider Yooralla.

While Ms Ryan said the committee secretariat had made efforts to make the inquiry more accessible with easy English documents and telephone submissions, she stressed that more needed to be done.

"Many do not have internet or the capacity to privately make a phone call or write a letter without support or at least without fear of intrusion by support staff," she said.

"People with disabilities also fear repercussions for speaking out, and this acts as a major barrier to hearing their views."

Ms Ryan said it was likely the vast majority of people living in institutional settings had been unable to contribute to the inquiry or were altogether unaware it existed.

"A royal commission is necessary to allow the time and resources to hear the views of people with disabilities, explore the extent and complexity of the issue, and hold support providers and individual perpetrators accountable," she said.

The Advocacy for Inclusion submission made 20 recommendations including national mandatory reporting for restrictive practices, an audit of crisis centres, and an independent statutory body for complaints.

Ms Ryan said there were no national studies on the prevalence of violence against people with disabilities in institutional settings or in the general community.

"However, it is widely documented that people with disabilities experience higher rates of violence than the general population, and women with disabilities are at particular risk," she said.

"Violence against people with disabilities can manifest in unique ways compared to violence against non-disabled people, and for this reason it often goes unrecognised."

Ms Ryan said the "extreme power dynamics" in institutional settings were a recipe for extreme forms of violence.

"When people with disabilities have no control over their supports and environments they are powerless and become vulnerable to violence," she said.

"This has been consistently observed by Advocacy for Inclusion in our direct interactions with individual advocacy consumers and advocates."