Pitch is the height of sound, ascribing meaning and emotion onto musical notes and spoken words.

 
Perfect pitch is the highly coveted ability to recognize any tone independent of a reference tone. And it’s quite rare, only 1 in 10,000 possess it. But some scientists believe that it’s not rare at all; research suggests that we were all born with this auditory gift, but because we didn’t need to use it, we lost it [1]. This is called the use it or lose it hypothesis.

 
During the first year of life babies are rapidly learning about their world, taking inventory of their experiences. These experiences are imprinted in the brain with the formation of new neural connections (tens of thousands of new connections every minute!). This experience-based learning is called plasticity. Connections that are stimulated are kept, but those that are not disappear – use it or lose it.

 
When applied to hearing sounds, this hypothesis states that babies are born wide-eyed and open, ready to perceive any and all sounds. But then culture steps in. The sounds of a particular culture, in both music and language, will be learned by babies and etched into their brains – they become naturally fluent for these sounds. Sounds that they did not learn will become foreign.

 

It is well known that there is a critical window for language acquisition that exists within the first year of life. During this time babies can learn the sounds of any language they are taught equally well as the sounds of their own language (see Surveying Sound: Your baby’s first critical window) [2].

 

With respect to music, three key discoveries laid the framework for the idea that there may also be a critical developmental window for perfect pitch early on, during this time of heightened brain plasticity:

 
1) Babies seem to have a naturally heightened pitch perception – babies only 9 months of age can recognize subtle changes to a note’s pitch that adults fail to notice [1].
2) The appearance of perfect pitch correlates to early onset of music training (in one study a whopping 40% of perfect pitch possessors started music training before age 4, and 78% before age 6! [3]).
3) Perfect pitch is far more common in speakers of tone languages, such as Mandarin and Vietnamese, and even more prevalent when these people had received music training [4, 5]. Further, this trend was dependent on how fluent the speaker was in the tone language and independent of their heritage [6].

 

 

It is easy to see how early musical training would foster perfect pitch, but why tone languages? In 2002, Diana Deutsch, a psychologist and expert in the study of perfect pitch, hypothesized that this phenomenon arose from the process of language acquisition. See, those singsongy tone languages of the Far East use different pitches to confer different meanings on a single word. For example, the word wen can mean to ask or to kiss, it’s all in how you say it. So, babies raised with these languages have heightened pitch perception simply because they have to in order to understand their own language.

 
The collective of decades of research on music and language acquisition suggests that babies’ auditory experiences during this key time of neuroplasticity dictates the extent of their auditory knowledge. Neural circuitry for processing music and language show significant overlap in the brain (see Music-Language Crosstalk in the Brain). These music-to-language-to-music transfers suggest that perfect pitch could be acquired like a second language. If music can be learned like language, and fluency is established in early life, then perhaps exposure to all possible pitches during this time can teach a baby musical fluency and foster the development of perfect pitch.

 
1.    Saffran, J.R. and G.J. Griepentrog, Absolute pitch in infant auditory learning: Evidence for developmental reorganization. Developmental Psychology, 2001. 37(1): p. 74-85.
2.    Kuhl, P.K., F.-M. Tsao, and H.-M. Liu, Foreign-language experience in infancy: Effects of short-term exposure and social interaction on phonetic learning. Proceedings of the National Academy of Sciences, 2003. 100(15): p. 9096-9101.
3.    Baharloo, S., et al., Absolute pitch: An approach for identification of genetic and nongenetic components. The American Journal of Human Genetics, 1998. 62(2): p. 224-231.
4.    Deutsch, D., T. Henthorn, and M. Dolson, Absolute pitch is demonstrated in speakers of tone languages. The Journal of the Acoustical Society of America, 1999. 106(4): p. 2267-2267.
5.    Deutsch, D., et al., Absolute pitch among American and Chinese conservatory students: Prevalence differences, and evidence for a speech-related critical perioda). The Journal of the Acoustical Society of America, 2006. 119(2): p. 719-722.
6.    Deutsch, D., et al., Absolute pitch among students in an American music conservatory: Association with tone language fluency. The Journal of the Acoustical Society of America, 2009. 125(4): p. 2398-2403.