An essential component in the process of acquiring a new language is the ability to listen. This occurs because there is a portion of speech sounds that, without conscious effort, can go unnoticed. The human mouth is capable of generating a vast range of noises that are perceived as distinct by the brain; considering all global languages, speech encompasses about 800 different sounds, or phonemes, although most languages use only approximately 40.
The infant brain is born prepared to process these 800 sounds. However, over time, it specializes: as the child is exposed to the sounds of their mother tongue, their brain adjusts to identify the specific phonemes of that language. For this reason, learning a second language after childhood can present difficulties, as the brain tries to process the new language using the calibration of the previous language, resulting in the omission of crucial details.
Even in adulthood, some people demonstrate greater ease in capturing the nuances of a new language. The explanation may lie in how their brains handle unfamiliar sounds. A recent study, published in the journal Journal of Experimental Psychology, points out that individuals with better auditory acuity (the ability to notice subtle details in sound) tend to classify new human sounds more as random noise than as language, which, counterintuitively, aids in learning the new language.
The study evaluated the auditory precision of 67 Japanese students who were learning English. The researchers measured each participant's aptitude for discerning minimal variations in frequency, duration, and timbre in certain sound signals. Subsequently, magnetic resonance imaging technology was used to monitor participants' brain activity while they listened to a series of English words, such as 'mad' and 'mud', or 'cat' and 'cut'. The challenge was to differentiate the phonetic pairs: in 'cat', the vowel 'a' is pronounced with the phoneme [æ] (similar to 'quet'), while in 'cup', the 'u' is pronounced as /ʌ/ ('cap'). The complication was that none of these phonemes corresponded directly to any vowel in the Japanese language, making distinction difficult.
In the end, while maintaining brain monitoring, the researchers asked the participants to identify the frequency difference between two very close tones. Analysis of the brain readings revealed that participants with sharper hearing (those who scored more accurately on the tests) showed less activation in the brain area dedicated to language processing when listening to the English words. It seemed they were treating the sound as any noise, and not as a distinct language.
At this point, the separation between 'noise' and 'language' is fundamental and is linked to brain organization. When we hear the human voice, the brain activates the left sensorimotor cortex, an area responsible, among other functions, for language processing, following the linguistic patterns of the individual's native language. Thus, the brains of participants with better auditory precision, who distinguished the English words better, relied less on this linguistic processing. On the contrary, the activity in the left sensorimotor cortex and the rest of the brain resembled that observed when the participant listened to any non-verbal sound.
In contrast, those who had more difficulty in the test showed greater activation of the left sensorimotor cortex, which is the area responsible for language processing. Kazuya Saito-van Poeteren, a linguist and professor at University College London, commented in a note: 'Students with a 'good ear' for auditory differences can hear a new sound from a foreign language objectively, without immediately processing it as 'language'. Instead, their brains analyze the acoustic information itself, and this may be the key to understanding why some people learn new languages more easily than others.'
He added that, although most people learn foreign languages by memorizing vocabulary and listening to speech, the study suggested that students can also benefit from training the auditory skills that support language learning itself.