Summary 
About 20 years ago, a landmark study found that toddlers before the age of 3 in low-income families would hear 30million less words than the more affluent families, putting them at disadvantage before they start school. Now, a growing number of researches has found that it’s the quality of communication between children, parents, and caregivers that is more important than the number of words children hear. According to research observations, the frequent use of parentese — the slow, high-pitched voice commonly used for talking to babies — were reliable predictors of language ability at age 2. Professor Anne Fernald of Stanford suggests that increased quantity of language inevitably leads to better quality. When you learn to talk more, you tend to speak in more diverse ways and elaborate more, and that helps the child’s cognitive development.

原討論文章: https://www.15mins.today/blog/ep-938-new-thoughts-on-math-of-effective-baby-talk  

Vocabulary and Sample Sentences:

Affluent adj. having a great deal of money The affluent families were previously thought to have an advantage in children’s development. Affluent communities tend to have more educational resources available for children   

Correlation n. mutual relationship or connection to two or more things The total number of words heard by a child has no correlation to the child’s future ability. Research has found high correlation between oil prices and the American dollar.   

Proficiency n. high degree of competence or skill Toastmasters club is a great place to improve your English proficiency. Language proficiency comes with practice and long-term use.