A Cross-linguistic Study Of Sensory Intelligence For Pre-attentive Extraction Of Abstract Auditory Rules

In the daily auditory environment,listeners are confronted with so many sounds with overlapping multiple acoustic properties as well as ambient noise.Although auditory signals are greatly chaotic,the brain can not only automatically analyze auditory inputs,but also extract invariant features or regularities shared by sounds,and even predict the next possible event.These perceptual achievements,which occur at the low level of sensory processing and without direct attention towards the sensory inputs,depend on a sensory intelligence.The sensory intelligence provides the basis for higher-level cognitive porcesses,such as speech comprehension.Speech,as an important communication tool carrying large amounts of information,is greatly variable.In spite of this,some features are often shared by dynamic speech sounds and keep invariant.These invariant features constitute so called abstract auditory rules in speech sounds.Previous studies demonstrate that there is a sensory intelligence in the speech perception.Based on this intelligence,the human beings can extract auditory rules from the complex speech sound stream at the pre-attentive stage to ensure speech communication without requiring limited conscious resources.Moreover,many corss-linguistic studies have shown experience-dependent strategies for speech perception.Language experience shapes the ability that the auditory system processes linguistically relevant features,even at the brainstem level.However,whether the sensory intelligence for extraction of abstract auditory rules in speech sounds is inherent or experience-dependent remains unclear.To address this issue,a complex speech sound stream was constructed by using 450 Mandarin Chinese monosyllables in the present study.Syllables always had a flat lexical tone to form an abstract auditory rule,although acoustic features,such as fundamental frequency values,format,durations and intensities,were randomly varied in the stream.This rule was occasionally and randomly violated by syllables with the rising,dipping or falling tone.Twenty native speakers of Mandarin Chinese and twenty native speakers of non-tonal languages were presented with the complex speech sound stream.The results showed that both Chinese and foreign speakers detected the violations of the abstract auditory rule in the speech sound stream at the pre-attentive stage,as revealed by the whole-head recordings of mismatch negativity(MMN).However,MMNs peaked earlier in Chinese speakers than in foreign speakers.Furthermore,Chinese speakers showed significantly different MMN peak latencies for the three deviant types,which were positively correlated with recognition points in the behavioral test.Foreign speakers showed no significant difference in MMN peak latencies.Theta activity increased for deviant relative to standard syllables in both Chinese and foreign speakers.However,Chinese speakers showed higher beta activity in right auditory cortex than foreign speakers did,possibly reflecting different mechanisms underlying pre-attentive extraction of the abstract rule of lexical tones.These findings indicate that the sensory intelligence for extraction of auditory rules in speech sounds is innate but shaped by language experience.Inherence and plasticity of the sensory intelligence provide the basis for high-level speech comprehension in complex linguistic environments.