[SOUND] So the nature of sound and speech sound is, is quite an interesting area of research in and of it's own, right? We'll consider it to some extent in this course, but the interesting part is that the ability to recognize speech was first thought to develop during the first year of life. What has emerged from the literature is that the ability to recognize speech appears very, very early. Recent work has suggested that even at birth there's already a bias towards the native language. Now, interestingly, when we look at bilingual infants we know that they may show certain behaviors. So for example, and we could ask the question, you know, how would you know that an infant is, is exhibiting some type of knowledge? And this is an interesting line of research that's been done with developmental psychology. There're many ways to do it. In the past, they would do things for example, like asking infants to look at something. So for example, the, the joke that I always like to use. It's not, maybe not a joke, just a slight, slight let's call it a half joke, right? Is that you know, if I were here lecturing in this class, right? To you for several weeks. And on one day, a guest lecturer appeared. And I always ask my students in class to pick a guest lecturer. They usually pick a male. And, and I say, well, let's pick someone like, let's say Brad Pitt. So let's say Brad Pitt showed up you know, as a guest lecturer. And suddenly he began giving this very perfectly beautifully rehearsed lecture. Well, for the first couple of minutes of Brad Pitt's lecture people would suddenly wake up. Right? Why is that? Well, because it's something new. In this case something novel. I've augmented that novelty by making it a movie star, but the point is that when things change, right? People notice. And you can see this in infants because you can ask them to look at a display and if they look away, it sort of means that they know what this is already and they're kind of bored. But if they look at a display longer, it means that they're not sure what it is. So when you change a display, and to an infinite looks the same, or you change a sound, and to an infinite sounds the same, they'll be bored. And they won't pay much attention to it. But if that change in the sound is perceived by the infant, then they'll take notice. Right? This is called habituation, dishabituation. It's been used for many, many years. It's a method that allows researchers to see what infants are processing. What differences they note. And you can look at the differences in speech to figure out whether an infant knows whether a speech sound differs or not. Other methods they've used is to look at the rate of sucking to see if they suck at a faster rate or a slower rate. And that can also play a role in figuring out you know, if they suck at a faster rate it means that it's something novel. If they suck at a slower rate, it means that they're slightly bored. And so its not new to them. And so there're different ways to look at infants and of course with the new imaging technologies you can also look at their brain activity. And, and we know from this work that fairly early on an infant can recognize the sounds of many languages, although there does seem to be a preference for the native language. And the second thing we can we can ascertain from this literature is that infants recognize the difference between two languages, if they learn two languages from a very young age. Now speech is a very intricate thing. All right? So we can consider the nature of speech as consisting of really what I'll describe as the melody of speech, and the notes of speech. Phonemes are these abstract ideas that come to represent single sounds, speech sounds in a particular language. One example that I like to give is my doctoral advisor, Elizabeth Bates. Back in, sometime in the late 1990s had come back from a trip to Florida. And during this trip she had been riding along with someone who told her that they had a horrible rice problem in Florida. And she didn't understand. She said, I didn't know if there was famine, you know, torrential rains. I mean, what was this huge, horrible rice problem that existed? And she finally realized that it wasn't a rise problem, it was a race problem. Now, you've noticed that I've used two sounds there. Rice and race. And she misheard the A in that particular American accent as an I. And you can see it's somewhat of a funny story, that misinterpretation she had of it. But it illustrates how speech sounds, right? Are mapped onto words. Right? So rice is one word, and race is a different word. Now, these phonemes, these speech sounds are very important for humans. In addition to speech sounds, the other thing we can think about is the melody of language. So, for example, language has what's called prosody. That's what linguists called prosody. It's the melody of the language. And it differs across languages. The example I like to give from English is a, a very distinct accent within American English. What's called the valley girl accent. >> I was like driving down the road, and this like, sun street. It's like it doesn't even matter, like, okay. This dog, just like all of a sudden just ran up and like hit my car. And I was like, this car cost me like, $25,000. Like, you just ran into like, my car. >> In this valley girl type of accent, it usually is characterized by a rising intonation. Right? At the end of a sentence. Almost makes it sound like a question. Now, we can compare the valley girl speech, or the valley girl accent, to the surfer dude. Right? The surfer dude sounds much more relaxed. You've probably heard this in several shows of people who speak very relaxed. They're usually on the beach, somewhere in California. That's where it originated. And you have this very surfer dude kind of accent. Now both of them are English. The phonemes are not equivalent necessarily, but very similar within standard American English. And yet the prosody is quite distinct between these two types of accents. Now this is an English, and an, specifically an American English. And if you really want to boil it down to California American English set of accents that illustrate this. But we can think about this as existing across many different languages, right? So every language has its own prosody. And even regional accents within that langauge will have different prosodies. Different ways in which the language kind of plays out, across time. Now, there are languages that have similar rhythmic properties. We could consider for example Dutch and English. Dutch and English have similar rhythmic properties. Obviously I'm not trying to say that Dutch and English are identical. Clearly they're different languages. And within the first year of life, infants who hear Dutch, or hear English, can detect the difference between their native language, and a language that has similar rhythmical properties. So two languages that are very similar that have been studied extensively with bilingual children, are Catalan and Spanish. This is work done by Sebastián-Gallés and Bosch. And this work has looked at these two languages. Right? Catalan and Spanish. That are very similar in their rhythmical properties, but differ in their sounds. So, for example, Spanish has a pretty restricted vowel space. It has five vowels. A, E, I, O, U. I don't speak Catalan, but Catalan has more vowels than Spanish. Right? So in order to speak these two languages, and to recognize them, infants have to be able to notice that these two vowel systems are different, right? And that the vowels in Catalan don't map on exactly to the vowels in Spanish, and vice versa. So the researchers wanted to ask two questions. The first question was, when do infants that speak only one language, notice the differences in these sounds? So, as you can imagine for an infant, right? Speech is coming in, there are these phonemes. And the point is, at what time can researchers detect the difference in the ability to, to realize that these two languages differ in the sounds, for a mono lingual? And then the second question, they wanted to ask was, is this time different for a bilingual? And of course, we'll consider this question, and this is a question that comes up quite often, right? Are bilinguals delayed in some way? Are they slower because they have to process two languages? And that's a very common question. One that we'll have some answers for as we go through the course. But here we can ask very easily and early, is there a delay in speech perception for a bilingual infant, relative to a monolingual infant? So and Bosch asked two groups of infants. One monolingual, one bilingual, to listen to rhythmically similar sentences. Right? In Catalan and in Spanish, and found that about four months of age, the monolinguals could detect the differences in the speech sounds. And this was identical to the age at which bilingual infants could detect these differences in the speech sounds. So essentially, it appeared that the bilingual infants were able to detect sounds from Catalan and Spanish, at about the same age as a monolingual infant could tell Catalan from Spanish, or Spanish from Catalan. Again, this suggests that there is no delay in the speech perception ability of bilingual infants. One of the most interesting phenomena that's been observed in speech perception, is the fact that infants appear to show specialization for their native language, by a year of life. Interestingly, my colleague Ping Lee at Penn State University has told me that on many occasions, when he presents these data of early specialization, undergraduates will come up to him after class and say, I don't understand. How is it that there's this early specialization, and yet you know, I learned English when I was five years of age, or four years of age, three years of age, and I don't have an accent? And, it's an interesting question. How is that possible? Right? If, if the window closes at a year, how was it that someone can acquire a language without an accent after that year? Well, a series of studies that were done to look at this question were performed by Patricia Cool and her colleagues. And in one study they asked, well, what would happen if we took an infant that's past this window, that no longer recognizes non-native speech contrasts? Right? So for example, you could take an infant in, in Japan and ask whether they can recognize the difference between L and R, pass this year. A difference that's not perceptible to adult Japanese speakers. In this case, Kuhl was in the United States, and she was going to test a group of English speaking monolingual infants and ask them to recognize tones in Chinese. Chinese is a tonal language. It uses tone to communicate. A word and what a word means. In this case, she was going to look at a contrast that existed in a language, Chinese, but did not exist in English. So she had two conditions. One condition was to have the infants watch a TV show, right? In Chinese. And the second condition was to have the infants interact with a Chinese native speaker, right? Just play a game essentially. While this Chinese native speaking adult would play this game, the infants would interact with her. And what she found was that, I know we would love for TV to be able to teach language to, or in this case a speech contrast to the infants. That condition did not turn out too well. So the infants who heard Chinese TV did not recognize these sounds afterwards. But those who interacted with a Chinese native speaker, suddenly reacquired this ability to recognize this marker. This tonal marker of meaning that exists in Chinese and not English. So what this indicates is that even when this window presumably closes, it's not completely closed. It can be reopened. And it offers us some answers to how it is that someone who's older, maybe three or five years of age, could actually learn a language, and sound like a native, and perceive it very similarly to a native. Specifically, it appears that their window reopened. Now, earlier we discussed this literature looking at the perception of Catalan and Spanish by bilingual and monolingual infants. The finding was that monolingual and bilingual infants could distinguish sounds across languages, and that the bilingual infants could distinguish in both directions, right? Without any delay. Now, more recent work by Laura-Ann Petito, extended this question by looking at infants in this first year of life who were having to perceive phonemes that existed in their language, or did not. So in this case they actually looked at the brain signals that correspond to perception of sounds that exist in two languages, and perception of a sound that did not exist in those two languages. So it was a non-native sound. Notice that these early, these are very early bilingual infants. So they have two native languages. And now we can ask the non-native question about bilinguals. When does the window close for these bilingual infants? The bilinguals of course could recognize both sets of speech sounds from each language. But not only that, even within the nine to 12 month range of age, at which modeling was no longer recognized non-native speech sounds. The bilingual infants could recognize non-native speech sounds. That is, they could recognize a third set of speech sounds that did not correspond to the two languages that they were hearing in their environment, and that they were learning to speak. It appears, based on these data, that not only does bilingualism not have a delay, it actually slows down the process of specialization. It leaves the window open longer, for other speech sounds.
