My baby is coming in four months, and I am doing my homework on how to teach it to talk. I have seen some studies show that babies cannot learn languages through voice recording and TV program, but I have also seen other studies state that babies can't see things beyond one meter distance in the first few months after birth. If the baby can't even see me, how can it know whether it's me or my recording is talking? Can I use my own voice recording to teach the baby to talk, least substitute some of my job, and make my life easier?
Recordings have been shown to not be as effective at promoting language development as a live person. This is most likely due to the fact that a baby doesn't recognize a recording as a person talking - it's just sound - and doesn't recognize a role in the speech. The baby needs the social element of talking - seeing another person talk, being in a conversation, and seeing the facial expressions and movements and all of the rest. Even a video recording doesn't work for this, as the baby doesn't recognize the person-on-TV as a person-in-actuality until much older (you can test this yourself; babies don't immediately recognize you on recordings.)
This article on language development from Parenting Science explains it fairly well. Two studies in particular are of interest here; one where they teach children Mandarin, some in person and some by video (But with the same information); the video was ineffective.
The second study was even more specific: it studied monologue versus conversation.
Researchers discovered that social talk—one-on-one, back-and-forth conversation between adults and their children—was linked with better language development. The more time babies and toddlers were included in adult conversations, the more quickly their language skills improved.
By contrast, listening to adult monologues—including storytelling--was only weakly correlated with language development. The effect of two-way conversations was almost 6 times greater than the effect of merely listening to adults talk.
So yes, you really do need to talk with your baby, and not just play a recording :) That's not to say a recording might not be helpful in instances where talking with the baby is not possible - such as a soldier deployed overseas - but it's not ideal compared to in-person talking and conversation!
Being present, interacting with your baby, and showing them the context of what you're saying is much more important and impactful than baby simply hearing your voice saying random words with no context. - It's correct that baby can't see clearly very far at first, making it that much more important that you get lots of up close face time with your baby. Teach them baby sign language too! That helps tremendously. Say the word, do the sign, and show the context by pointing things out or holding the object where they can see it. - As a parent of 2, and a parenting coach, I would see very little value of playing a recording of my voice.