Are some people actually tone deaf?

Sure, not everyone has pipes like Adele. But we all know people who truly struggle to match and comprehend musical pitch, and they're usually labeled "tone deaf." But is tone deafness a real condition? And if so, why are some people tone deaf? 

In short, yes, tone deafness is a genuine neurological disorder. It's called amusia. However, not everyone who lacks musical skills has this condition, which affects an estimated 4% of the population.

Amusia can range in severity, from a mild difficulty in recognizing melodies to a complete inability to distinguish between different musical notes. But what causes this condition? For the majority of sufferers, it's hereditary, said Isabelle Peretz, a professor of psychology at the University of Montreal who specializes in the neurocognition of music.

"Most amusics are born that way. Half of their brothers and sisters are born that way, too, because congenital amusia is hereditary," Peretz told Live Science. "An impoverished musical environment does not seem to be the issue. Children as young as 8 have been shown to have amusia. They have the same abnormal profile as amusic adults."

Some people can develop amusia later in life, usually as a consequence of having a stroke or serious brain trauma. This is known as acquired amusia, and is a far less common form of the condition.

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"One of the main consequences of having congenital amusia is that you are likely to struggle with recognizing music you have heard before, without the help of song lyrics," Karen Wise, a research fellow at the Guildhall School of Music & Drama in London, told Live Science. "But amusia varies from person to person, and so do the experiences of amusic people.

The most common form of amusia is pitch-based, Wise noted. A small 2002 study on 11 adults with musical impairments also found this, suggesting that congenital amusia is related to "severe deficiencies in processing pitch variations," the authors wrote in the paper, published in the journal Brain.

"Many amusics have elevated pitch perception thresholds, so the difference in pitch needs to be much bigger before they can perceive it," Wise said. "They may also struggle to perceive the difference between upward and downward pitch changes, and do not perceive the patterns made by sequences of musical notes.”

Despite this challenge, musically impaired people in the 2002 study were able to process and recognize common environmental sounds, human voices and speech prosody, or the rhythm and musical quality of speech, as "the disorder appears specific to the musical domain," the authors wrote in the study. For example, they were able to recognize when someone was asking a question versus making a statement, possibly because differences in speech intonation "use variations in pitch that are larger than half an octave, to convey relevant information," according to the study. "In contrast, melodies use mostly small pitch intervals."

That said, some studies show that people with pitch-based amusia do have difficulties processing melodic information in speech, Wise said. "However, usually intonation is not the only cue we rely on for understanding spoken communication, so in daily life this is likely to be much less noticeable," she added.

While some individuals with amusia are fully aware they have it, others can live for years — potentially their whole lives — without knowing about their condition. This is because tone deafness can manifest in different ways, and its severity varies from person to person. For instance, some people may have difficulty singing in tune or perceiving melody, while others may struggle to distinguish among instruments or notes. 

Some people may have unwittingly found ways to compensate for their condition by relying on other cues, such as lyrics or rhythm, which can mask their inability to perceive pitch accurately. 

"Like dyslexics can learn how to read, those with amusia should be able to improve [their ability to recognize tone] if they start early enough," Peretz said. 

Neural studies hint that it might be possible to help those with amusia.

"Brain imaging shows that amusic brains receive and respond to pitch information, but it is not reaching conscious awareness. The neurons fire in response to pitch differences that the person themselves can't distinguish," Wise said. "Maybe if we could develop training methods that would harness that unconscious response, we could find a way to overcome it."

In all, there appears to be an amusia continuum, Graham Welch, chair of the U.K.-based Society for Education, Music and Psychology Research, told Live Science. It's likely that "movement along the continuum is possible in a nurturing environment, either through conscious design pedagogically, or serendipity in the context of music making and experience in the home and local environment," he said.

If you are curious about whether you have amusia, you can take one of the tone deafness tests available online.