Sounds are abound in our rich auditory world. As humans we take them in, wrap them in culture, create language. Neuroscientists have long been interested in understanding this uniquely human process of language acquisition. When does language learning begin and when does a person become bound to their unique language? Researchers have discovered that this highly complex process begins far earlier than anyone imagined.
A fetus can hear by month 5 of pregnancy and by birth is hardwired to discern all possible phonemes (units of sound) of any language. But, in a short period of time, babies will lose this ability and become culture-bound to the sounds of their language.
At 10 months, before their first birthday, long before learning to talk, babies have already evaluated and dedicated themselves to their native tongue. Dr. Patricia Kuhl, a pioneer in the field of language acquisition, found that babies start this process in utero; newborn babies show a strong preference for the sounds of their mother’s language over foreign languages (Moon, Lagercrantz, & Kuhl, 2013). Even so, babies remain open and will take inventory on any sounds they are exposed to until 6-8 months of age. Around this time babies enter a critical but brief developmental window where they focus on the unique sounds of their language. You may better recognize this as the “babbling” stage. All that babbling is really your baby learning and trying out these sounds. And your baby can learn the sounds of any language during this time provided the presentation is in the context of social interaction (Kuhl, 2010). Thus, over the course of only 4 months, your babbling baby is actually transitioning from phonetic-openness to language-bound phonetic perception.
This is dubbed the “use it or lose it” hypothesis. Simply put, if babies do not need to recognize certain sounds, tones, or pitches they lose the ability to do so. Consider a baby’s brain comprised of millions of neurons branching out, interacting with one another by forming synaptic connections. The more you stimulate a synapse, the more you reinforce the connection. But when certain synapses are not reinforced they fade away – use it, or lose it.
This hypothesis suggests that stimulation of these connections at specific times could enhance and reinforce neural connections that would otherwise be lost. The discovery of such developmental milestones has fueled the field of cognitive neuroscience as researchers now study the impact of this ‘window of opportunity’ on social, emotional, and cognitive development through the use of both language and its cultural predecessor, music. It is believed that, much like in phoneme recognition, babies are “ Universalists” in the ability to perceive the tones of music from any culture. Indeed, studies have shown that during this window of time babies are superior to musically untrained adults at recognizing pitch changes within melodies, especially in culturally unfamiliar music.
The uniquely human experiences of music and language during early development shapes and directs our complex neural circuitry. Music and language engage multiple regions of the brain to promote sophisticated cross-talk between distinct neural circuits involved in pitch perception, word recognition, memory, emotion, and motor responses to name a few. Thus, knowledge of these critical windows of time during cognitive development provides a wealth of possibilities to not only expand upon the brain’s potential but also to identify therapeutic targets for developmental disorders.
(2010). Patricia K. Kuhl: The Linguistic Genius of Babies [Retrieved from [Video file] https://www.ted.com/talks/Patricia_kuhl_the_linguistic_genius_of_babies?language=en
Moon, C., Lagercrantz, H., & Kuhl, P. K. (2013). Language experienced in utero affects vowel perception after birth: a two‐country study. Acta Paediatrica, 102(2), 156-160.