When it comes to the best time to teach your baby a second language, Erika Levy, Ph.D., CCC-SLP, Associate Professor of Communication Sciences and Disorders at Teachers College, Columbia University says, "The earlier the better! Even within the first 6 months of life, babies become keenly aware of the speech sounds in the languages that surround them."

Dr. Levy explains to Romper that the best time to begin teaching your baby a second language is before the one year mark. "After the first year or so, it becomes much more difficult for them to 'hear' the many vowels and consonants that don't exist in the language(s) they are surrounded by (i.e., in a non-native language)," she says. "Their perceptual differences from native speakers of the language will become evident in their accents when they later try to speak that non-native language. Some of these perceptual changes may be reversible, but the timeline for native-like pronunciation is very early and differs depending on the speech sounds and languages in question — perhaps by age 3 or 5, but certainly before puberty for most people. Other aspects of language (vocabulary, grammar, etc.) are also developed best early, probably by puberty for most people."