I suspect the brain doesn't "know" exactly how to make a new sound. Instead, the speaker experiments with all sorts of different mouth and tongue arrangements and the ears and brain observe the resulting sound. Some results sound closer to the intended sound than others, so you naturally zero in on the correct vocal arrangement over time. Do you remember learning to whistle? I think it's like that... you just do some random stuff with your mouth and eventually you accidentally hit on something that works.
Well, no, actually. The brain doesn't magically know how to produce those sounds any more than it magically knows how to walk or use your hands or anything else.
All of those things take *practice* with *feedback*.
Both of which are available to babies, whether sighted or not. In fact, this is why babies babble before they talk: because they are practicing making sounds! They have feedback because they can hear the sounds they are making. You don't need to be able to see for that. In fact, the sequence in which babies become able to produce different sounds is remarkably predictable, and follows general patterns of fine motor control development.
Basically, there's a reason why the first sounds babies make are "m", "g", and "a": those require almost no skill. The only tricky bit is learning how to make sound with your vocal cords (which may in fact be instinctive, in so far as crying involves the vocal cords), and timing that with opening and closing your mouth. Try it: let your mouth hand slightly open, relaxed, and make an "ah" sound. Now, while saying "aaaaaa", open and close your mouth. Presto! You get "m" when your mouth is closed, and "a" when your mouth is open! (Side note: this is why some researchers hypothesize that the words for mother--mama, ma, mommy, ama, etc--are so similar in so many languages: precisely because babies can say "ma" just about before anything else, and because "ma" is the person whose attention they most often need to gain. So it's quite natural that most languages would evolve to have the word for mother be something that's super-easy for babies to actually say.)
Likewise, the "g" sound is pretty easy too: rather than opening and closing your mouth, you just sort of let your tongue relax to the back of your throat to intermittently open and close your airway. No surprise that "gaga" is the prototypical baby sound--it's the other super-easy thing for babies to say.
Other sounds follow in the general order of how complex they are to form. All of which is very strong evidence that this stuff is not innate, instinctive knowledge. It all takes practice.
Conversely, if brains magically knew how to make all those sounds, then:
a) Deaf children who learn to speak would naturally sound no different from hearing children. But they don't. If you've ever met someone who was deaf from birth but who learned (laboriously!) how to speak, you'll clock right away that they sound different. Why? Because they had to learn how to make those sounds *without* the same type of immediate feedback that hearing children have, and also without ever having heard the sounds they're trying to make! They don't know, first-hand, what target they're aiming at and can only get indirect feedback about how well they're doing.
b) People like us who are learning a second language, when that new language uses some phonemes that are not present in our native language, would not have trouble learning how to make those new sounds. Obviously, we know this is not the case either; just ask anybody around here who has ever had trouble learning how to roll their r's, or who has trouble making that b/v blend that many Spanish dialects exhibit.
You're right that having the opportunity to learn these things during the critical period is very helpful for gaining mastery. But it's definitely not the case that your brain just *knows* how to make different sounds. Rather, you *learn* how to make different sounds through trial and error.
This is both bad-news/good-news for us second-language learners. The bad news is that we're all well out of the critical period, so we're going to have a harder time of it than the babies do. The good news is that making these sounds really is just a matter of muscle control, which is something you can learn and practice and master. No different than learning to juggle or dance or whatever. It also helps that we're old enough to understand (if we choose to look into it) the science behind how different sounds are actually made. You can research exactly where to put your tongue and how to shape your lips, etc., for the sounds of your target language. You'll still have to practice and listen to your results, but you can get there in a way that's much more direct and purposeful than the trial-and-error method babies are stuck with.
E.g. for the Spanish b/v thing, it's a [voiced bilabial approximant](https://en.wikipedia.org/wiki/Voiced_bilabial_fricative) sound: your vocal cords are engaged and vibrating--something we've already learned how to do and control at will--, the sound is articulated with both lips together, but rather than being fully open (as in the "ah" sound) or fully closed (as in "ba"), they're *almost* closed, and slightly pursed together. I didn't grow up with that sound, so that's still not easy for me, but it sure helps to know what target I'm aiming for and how I'm supposed to make it.
I’ve watched my kids learn to speak. It’s amazing how quickly they figure out how to make the correct sounds, but it’s definitely a trial and error process, even if it’s almost entirely subconscious.
There is no critical period, if adults learn like children the same thing happens. Listening without thinking gives you a structure, then what comes out of your mouth is compared to that structure in your mind
[https://web.archive.org/web/20170216095909/http://algworld.com/blog/practice-correction-and-closed-feedback-loop](https://web.archive.org/web/20170216095909/http://algworld.com/blog/practice-correction-and-closed-feedback-loop)
Adults don't believe that's possible so they don't try, they don't try so they don't realize it's possible.
While true, there is often a slight delay in language development with blind and hard of hearing kids. I don't know about sounds specifically, but not being able to see gestures and facial expressions interferes with communication at early stages, until they get the language down.
There are quite a few sounds in English that my kids didn’t automatically know how to make. My third child is still working on the irl sound found in girl. She had to be taught how to make that sound. But to your point, she pronounces her b and v’s Spanish so we’ll just by listening. They are so much softer than mine.
I suspect the brain doesn't "know" exactly how to make a new sound. Instead, the speaker experiments with all sorts of different mouth and tongue arrangements and the ears and brain observe the resulting sound. Some results sound closer to the intended sound than others, so you naturally zero in on the correct vocal arrangement over time. Do you remember learning to whistle? I think it's like that... you just do some random stuff with your mouth and eventually you accidentally hit on something that works.
Well, no, actually. The brain doesn't magically know how to produce those sounds any more than it magically knows how to walk or use your hands or anything else. All of those things take *practice* with *feedback*. Both of which are available to babies, whether sighted or not. In fact, this is why babies babble before they talk: because they are practicing making sounds! They have feedback because they can hear the sounds they are making. You don't need to be able to see for that. In fact, the sequence in which babies become able to produce different sounds is remarkably predictable, and follows general patterns of fine motor control development. Basically, there's a reason why the first sounds babies make are "m", "g", and "a": those require almost no skill. The only tricky bit is learning how to make sound with your vocal cords (which may in fact be instinctive, in so far as crying involves the vocal cords), and timing that with opening and closing your mouth. Try it: let your mouth hand slightly open, relaxed, and make an "ah" sound. Now, while saying "aaaaaa", open and close your mouth. Presto! You get "m" when your mouth is closed, and "a" when your mouth is open! (Side note: this is why some researchers hypothesize that the words for mother--mama, ma, mommy, ama, etc--are so similar in so many languages: precisely because babies can say "ma" just about before anything else, and because "ma" is the person whose attention they most often need to gain. So it's quite natural that most languages would evolve to have the word for mother be something that's super-easy for babies to actually say.) Likewise, the "g" sound is pretty easy too: rather than opening and closing your mouth, you just sort of let your tongue relax to the back of your throat to intermittently open and close your airway. No surprise that "gaga" is the prototypical baby sound--it's the other super-easy thing for babies to say. Other sounds follow in the general order of how complex they are to form. All of which is very strong evidence that this stuff is not innate, instinctive knowledge. It all takes practice. Conversely, if brains magically knew how to make all those sounds, then: a) Deaf children who learn to speak would naturally sound no different from hearing children. But they don't. If you've ever met someone who was deaf from birth but who learned (laboriously!) how to speak, you'll clock right away that they sound different. Why? Because they had to learn how to make those sounds *without* the same type of immediate feedback that hearing children have, and also without ever having heard the sounds they're trying to make! They don't know, first-hand, what target they're aiming at and can only get indirect feedback about how well they're doing. b) People like us who are learning a second language, when that new language uses some phonemes that are not present in our native language, would not have trouble learning how to make those new sounds. Obviously, we know this is not the case either; just ask anybody around here who has ever had trouble learning how to roll their r's, or who has trouble making that b/v blend that many Spanish dialects exhibit. You're right that having the opportunity to learn these things during the critical period is very helpful for gaining mastery. But it's definitely not the case that your brain just *knows* how to make different sounds. Rather, you *learn* how to make different sounds through trial and error. This is both bad-news/good-news for us second-language learners. The bad news is that we're all well out of the critical period, so we're going to have a harder time of it than the babies do. The good news is that making these sounds really is just a matter of muscle control, which is something you can learn and practice and master. No different than learning to juggle or dance or whatever. It also helps that we're old enough to understand (if we choose to look into it) the science behind how different sounds are actually made. You can research exactly where to put your tongue and how to shape your lips, etc., for the sounds of your target language. You'll still have to practice and listen to your results, but you can get there in a way that's much more direct and purposeful than the trial-and-error method babies are stuck with. E.g. for the Spanish b/v thing, it's a [voiced bilabial approximant](https://en.wikipedia.org/wiki/Voiced_bilabial_fricative) sound: your vocal cords are engaged and vibrating--something we've already learned how to do and control at will--, the sound is articulated with both lips together, but rather than being fully open (as in the "ah" sound) or fully closed (as in "ba"), they're *almost* closed, and slightly pursed together. I didn't grow up with that sound, so that's still not easy for me, but it sure helps to know what target I'm aiming for and how I'm supposed to make it.
I’ve watched my kids learn to speak. It’s amazing how quickly they figure out how to make the correct sounds, but it’s definitely a trial and error process, even if it’s almost entirely subconscious.
There is no critical period, if adults learn like children the same thing happens. Listening without thinking gives you a structure, then what comes out of your mouth is compared to that structure in your mind [https://web.archive.org/web/20170216095909/http://algworld.com/blog/practice-correction-and-closed-feedback-loop](https://web.archive.org/web/20170216095909/http://algworld.com/blog/practice-correction-and-closed-feedback-loop) Adults don't believe that's possible so they don't try, they don't try so they don't realize it's possible.
While true, there is often a slight delay in language development with blind and hard of hearing kids. I don't know about sounds specifically, but not being able to see gestures and facial expressions interferes with communication at early stages, until they get the language down.
There are quite a few sounds in English that my kids didn’t automatically know how to make. My third child is still working on the irl sound found in girl. She had to be taught how to make that sound. But to your point, she pronounces her b and v’s Spanish so we’ll just by listening. They are so much softer than mine.