Hearing voices in your head is so common that it is normal, psychologists believe.
Some who hear voices fear being branded as "crazy"
Dutch findings suggest one in 25 people regularly hears voices.
Contrary to traditional belief, hearing voices is not necessarily a symptom of mental illness, UK researchers at Manchester University say.
Indeed, many who hear voices do not seek help and say the voices have a positive impact on their lives, comforting or inspiring them.
Researcher Aylish Campbell said: "We know that many members of the general population hear voices but have never felt the need to access mental health services.
"Some experts even claim that more people hear voices and don't seek psychiatric help than those who do."
Some who hear voices describe it as being like the experience of hearing someone call your name only to find that there is no one there.
People also hear voices as if they are thoughts entering the mind from somewhere outside themselves. They will have no idea what the voice might say. It may even engage in conversation.
The Manchester team want to investigate why some people view their voices positively while others become distressed and seek medical help.
Ms Campbell said: "It doesn't seem to be hearing voices in itself that causes the problem.
"What seems to be more important is how people go on to interpret the voices."
She said external factors, such as a person's life experiences and beliefs, might influence this.
"If a person is struggling to overcome a trauma or views themselves as worthless or vulnerable, or other people as aggressive, they may be more likely to interpret their voices as harmful, hostile or powerful.
"Conversely, a person who has had more positive life experiences and formed more healthy beliefs about themselves and other people might develop a more positive view of their voices."
Past studies have found that people who hear voices have often had a traumatic childhood.
Ms Campbell said stigmatisation could also play a role.
"If a person starts hearing voices and also holds the beliefs of some of society that this means they are mentally ill, it is going to cause them more distress. It also stops them talking about it to others."
Professor Marius Romme, president of Intervoice, a "hearing voices" charity, said: "Because of the fears and misunderstandings in society and within psychiatry about hearing voices, they are generally regarded as a symptom of an illness, something that is negative to be got rid of, and consequently the content and meaning of the voice experience is rarely discussed.
"Our work and research has shown more than 70% of people who hear voices can point to a traumatic life event that triggered their voices; that talking about voices and what they mean is a very effective way to reduce anxiety and isolation; and that even when the voices are overwhelming and seemingly destructive they often have an important message for the hearer."
Paul Corry of the mental health charity Rethink said: "Rethink welcomes this investigation, which we hope will help support our campaign to bring mental health issues into the mainstream."
People interested in participating in the University of Manchester research should call 0161 306 0405 or email email@example.com.
Participants should be aged 16 or over, have been hearing voices for at least six months and live in the northwest of England.