KEY POINTS:
Whether it's a karaoke screecher or a shower squawker, we've all seen - or heard - someone try to sing who probably shouldn't.
But while up to one in five Australians blame their woeful voice on tone deafness, far fewer are truly tone deaf. An estimated 4 per cent suffer from the condition, which is correctly known as amusia.
"A lot of the people who are self-declared tone deaf are perfectly normal and they just don't have very good vocal control," says Macquarie University's Professor Bill Thompson, who presented new research into amusia at a conference in Sydney last week.
"They know they're not singing in tune ... and with training they could easily learn to sing."
Those afflicted by amusia, however, genuinely don't know they can't sing.
It's not yet clear whether amusics can be "trained" to sing or whether a key part of their brain circuitry is "missing", he says.
"They're often the ones belting out songs at parties and singing right off-key because they genuinely do not hear that things are not right," Professor Thompson says.
"If you play Happy Birthday and you make one note really foul these tone deaf people don't even hear it. They just say, 'It sounds fine to me'."
It's also unclear whether the condition is genetic or acquired during early development - possibly in the womb.
Professor Thompson told the international music communication science conference at the University of NSW that his research suggested people suffering from amusia might also have difficulty picking up nuances such as anger, fear or sarcasm in everyday speech.
It is the first time tone deafness has been linked to speech intonation insensitivity.
Professor Thompson's research shows amusics often miss out on the subtle shades of meaning conveyed by a person's tone of voice.
The study found tone deaf individuals had dramatic difficulties decoding emotions such as fear and irritation.
"It is possible that somebody who is completely tone deaf might not pick up that somebody they're talking to is getting increasingly irritable," he says.
"It kind of makes sense because music communicates emotions through changes in pitch, changes in loudness and through its pace and timbre - all of the same qualities that communicate emotions in speech and tone of voice," he says.
Tone of voice, or "speech prosody", can change the meaning of a sentence.
"For example if someone says 'It's nice to see you', you don't know whether they're being sarcastic or if they're genuinely happy," Professor Thompson says.
Instead, amusics need to rely on context or body language to pick up on a person's meaning.
Amusics don't appear to have trouble with the more obvious emotions such as happiness and sadness, he adds.
Professor Thompson says there's a chance that research like his could lead to a cure for amusia.
"The next step is to see whether you can retrain people who are tone deaf and nurture a greater sensitivity to the nuances of music," he says.
"That will tell us whether they're actually missing neurocircuitry - they're missing that part of the brain, and nothing can be done - or whether it's something we can train."
One person who makes training the musically challenged to sing her business is Gillian Bonham, who runs the Tone Deaf Clinic in Surry Hills, Sydney.
She says singing is simply "a set of physical skills".
Her students learn about posture, relaxing the body, breathing and "most importantly" listening skills.
Ms Bonham teaches 60 people each year and claims to have a 100 per cent success rate.
She says she's even taught profoundly deaf students to hold a tune, but she admits she's "not sure" about the success she'd have with true amusics.
But for everyone else, she argues, it's a matter of overcoming fear.
"A lot of the problem is psychological, because they've been told by a parent, a teacher, a sibling or a child that they can't sing," Ms Bonham says.
"My job is to cut through all that rubbish.
"They stand up there and they will sing and get the biggest highs of their lives.
"They just beam."
- AAP
