Singing along to the radio, dancing till your feet won’t carry you anymore, having an earworm that you just can’t get rid of or chilling to your favorite music at night – those are familiar things to most of us, but strange habits to amusics.
Most of us recognize, understand and appreciate music. But music is always out of tune for a few others. Amusics can’t recognize familiar melodies without lyrics, not even “Happy Birthday”. They can’t sing in tune either or detect whether a note within a melody is out of tune or key. They also can’t recognize out-of-tune singing–which can also be a benefit if you think about all those casting shows–and they can’t hold melodies in their head, even if they have heard them moments before. In addition, about half can’t reproduce a rhythm, meaning they can’t clap along or synchronize to music sufficiently well to dance.
A pitch of meaning and emotion
Congenital amusia – the scientific term for tone-deafness – is present right from birth. Amusics can hear normally, they have had no brain trauma and their exposure to music in childhood has been normal. But their brains never learn to process pitch correctly; they have a selective impairment for music perception – or so it was thought for the longest time.
Researchers found that amusia also affects language perception1. The discovery is not surprising as language is also part of the auditory domain and uses pitch and rhythm to convey certain meanings. In so-called tonal languages, such as Mandarin, for example, the pitch of a word determines its meaning. In English, we use pitch changes to denote the stress in a sentence and to signify emotions. Amusia affects statement and question discrimination, emotion perception, and tone language perception.2,3,4. But to music or language teachers, educators, psychologist, speech and language therapists, this disorder and the impairments amusics face are little known.
To some amusics, music is just not interesting and they simply ignore it; to others, music is an annoying banging, and, for the most extreme cases, it means headaches and concentration problems. The lack of music perception can lead to amusing situations. One woman, who was diagnosed with amusia in our Lab, was once in an elevator with friends and started hearing a strange, squeaking noise. Worried that there could be a problem with the elevator, she asked her friends whether they could hear that creak. Her friends, at first puzzled, remembered her amusia and told her what she was hearing was a saxophone.
However funny we find the stories to be, amusia can also lead to social problems with partners, parents or friends, always asking: Why don’t you want to go to your music lessons? Why won’t you dance with me? Why are you not coming to that concert with us? It is a huge relief for amusics to find out their condition. They usually know that they have trouble with music and, no matter how hard they try, they do not get better at it (there is no lasting intervention or cure for amusia yet). However, they are not aware that this is caused by a disorder that has a name and that others are affected. Studies estimate that between 1.5% and 4% of the population is affected by amusia 5,6,7 and more research is looking at different aspects of this disorder.
A growing field
The field of congenital amusia research – a term coined in 2001 – is still a relatively young one, even though the first anecdotal case report was published in 18788. At first, pitch perception and production in music were found to be impaired in music. Now, many other areas are also being investigated, from rhythm perception and beat synchronization to timbre and musical emotion perception. Special attention is also being paid to the underlying cause in the brain: a pitch processing deficit, an auditory memory deficit or a statistical learning deficit. It is still unclear which of these, or more likely, which interplay of these factors causes the disorder. There are just as many theories where and when in the brain something goes wrong.
At the Phonetics Laboratory at the University of Amsterdam and the Phonetics Laboratory at the University of Duesseldorf, we are part of this research effort by investigating how language perception is affected by amusia. We found that amusia affects intonation, word stress, and vowel perception, at least under laboratory conditions. That means if we take away all context, gestures and facial expression, and amusics can solely rely on what they hear, they have a much harder time than unaffected participants. However, in everyday life, they seem to do mostly fine with language and they can’t be recognized by having a monotone intonation, for example. That means they must have somehow learned to produce a normal intonation and to use other cues in everyday communication. We are interested in what those cues might be. To investigate this, we run studies investigating not only the behavioral reactions of amusic to acoustic stimuli but also their reaction time and their brain waves, hoping to gain insights into what their brain is doing differently.
 Patel, A. D., Wong, M., Foxton, J., Lochy, A., & Peretz, I. (2008). Speech Intonation Perception Deficits In Musical Tone Deafness (Congenital Amusia). Music Perception: An Interdisciplinary Journal,25(4), 357-368. doi:10.1525/mp.2008.25.4.357
 Hamann, Silke, et al. “Perceiving differences in linguistic and non-linguistic pitch: a pilot study with german congenital amusics.” Proceedings of the 12th International Conference on Music Perception and Cognition and the 8th Triennial Conference of the European Society for the Cognitive Sciences of Music. 2012.
 Liu, Fang, et al. “Intonation processing in congenital amusia: discrimination, identification, and imitation.” Brain 133.6 (2010): 1682-1693
 Thompson, William Forde, Manuela M. Marin, and Lauren Stewart. “Reduced sensitivity to emotional prosody in congenital amusia rekindles the musical protolanguage hypothesis.” Proceedings of the National Academy of Sciences 109.46 (2012): 19027-19032.
 KALMUS, H. and FRY, D. B. (1980), On tune deafness (dysmelodia): frequency, development, genetics and musical background. Annals of Human Genetics, 43: 369-382. doi:10.1111/j.1469-1809.1980.tb01571.x
 Peretz, Isabelle, and Dominique T. Vuvan. “Prevalence of congenital amusia.” European Journal of Human Genetics25.5 (2017): 625.
 Pfeifer, Jasmin, and Silke Hamann. “Revising the diagnosis of congenital amusia with the Montreal Battery of Evaluation of Amusia.” Frontiers in human neuroscience 9 (2015): 161.
 Allen, Grant. “Note-deafness.” Mind 3.10 (1878): 157-167.