Despite everything scientists have learned about the human body and the way our brains work, there are still so many everyday experiences that leave most of us wondering whether we're normal - like, does everyone hear a voice in their head while reading, or am I crazy?

Thankfully, there are no questions too obscure for researchers to ask (and then report back to us with a statistically significant answer), and a small online study suggests that we're not alone, and a lot of other people also hear a voice speaking the words to them as they read.

That said, this is one of the first studies on this topic, and it's limited by the fact that it analysed the unregulated contributions of 160 people through - wait for it - Yahoo! Answers. Yes, the study has been peer-reviewed and published, but we should still take it with a big grain of salt.

Still, it's a good starting point for the largely unexplored topic of inner voices. Once assumed to be a sign of auditory verbal hallucinations, researchers are beginning to realise that they might be more common than previously though. And although research has been done on how these inner voices differ to our own speaking voices, no one's ever really taken the time to simply find out how common the phenomenon is, until now.

To assess just how many people hear a voice while reading (which the researchers call an 'inner reading voice', or IRV) psychologist Ruvanee Vilhauer from New York University headed somewhere she knew people loved to vent their thoughts - Yahoo! Answers, which is the largest English language Q&A website in the world.

She found 160 posts on the topic of an inner reading voice, including 136 answers and 24 questions, and then worked with an independent coding team to categorise the content so it could be quantified and analysed.

This is a standard technique used in psychological research, and it helps researchers to compare non-standardised responses - for example, the code could be used to measure things like how often people confirm having an internal reading voice, or admit to being unsure about it.

Out of the 160 posts, Vilhauer found that 82.5 percent of the people posting had heard one or more voices while reading. Most of these people also assumed it was totally normal - "We all hear our voices in our heads at times - even those of others we know - especially while reading," answered one Yahoo! contributor. 

But 10.6 percent said they'd never heard a voice while reading, and were equally adamant about being normal ("Nooo. You should get that checked out," wrote one respondent. Another added "NO, I'M NOT A FREAK"). 

Out of the people who did hear a voice while reading, some mentioned that they heard multiple voices, including character accents, while some only heard one voice, which usually reflected their own speaking voice. 

Nearly everyone who heard an inner reading voice talked about it being 'audible' in some way - for example, referring to volume, depth, or accent. Some people also mentioned that they found the voice distracting or scary. 

Interestingly, 10 of the posters only noticed their inner reading voice when the question was asked. "Now, that you've mentioned it, I realise that I do hear a voice in my head," one commenter wrote.

The research has been published in the journal Psychosisand Vilhauer thinks her results support the hypothesis that auditory hallucinations are often inner voices that are simply incorrectly identified as belonging to someone else. 

Fascinatingly, Vilhauer's research might also help to explain why scientists have never asked this question before.

"Vilhauer speculates that perhaps psychologists have failed to study this question because they've simply assumed, like many of the Yahoo contributors, that there's no variability in this and everyone has the same reading experience as they do," writes Christian Jarrett for the British Psychological Society blog.