 Good evening, we will continue to talk about production of a speech sounds and the other day I told you that vocal cords have a very complex structure, they perform a variety of functions, we are you know can you name some of them, we are able to hear one another because of vocal cords, we are able to whisper because of vocal cords, we are able to bring a variety of tones because of vocal cords and you know similar social functions are performed by vocal cords, many people have called vocal cords something like resonator or phonator which carries voice to a distance, the other day we also saw how vibrations can change and changing vibrations produce different kinds of voice tones, all of these things can be computed, can be computerized, you can synthesize, you can create artificial voice to a large extent, a lot has happened by way of engineering, a lot has happened by way of human understanding of the production of speech sounds. Let us summarize, the other day I also said that primarily vocal cords can be in one of the three positions, do you remember I also said that it is because of the vocal cords that men sound different from women and both men and women sound different from children, why do men sound different from women? Length, can you please speak loud and so that the camera can catch you, the length is different Length of what? Length of erythenoid cartilage, what is it? Erythenoid cartilage, erythenoid cartilage is different among men from women, how long is it among men? Among men it is generally speaking 21 millimeters, among women adult women have it about 18 millimeters long and in children it is shorter, that is why you know our voices differ, but you know each individual it is not that you and I and all of us have only 21 millimeters, it could be a nano millimeter more or less. Just as no two people here are the same height, same length, same weight, same complexion, there are some you know minuscule, some minor differences, so is it there also in the erythenoid cartilage and that gives us our unique voice. Similarly, there can be in a very, very lose, very generalized sense three positions of the vocal cords, vocal cords can be in three thousand different positions in hundreds of thousands of different positions, but if you classify them you know what we do in sciences is we impose arbitrary classification on natural data, natural data are not all as clear cut as we see here three positions, do you understand yes or no please, you know the nature has greater variety, far greater variety than just to say black and white, there is gray, there is brown, there is yellow, there are other colors in between, so similarly vocal cords can be in many different positions, but for the sake of description, for the sake of a study we say that vocal cords can be in one of the three positions, what are the three positions look at the, look at the screen and there can be position A, what is it in position A, vocal cords are fully closed, tight shut, no air can come out of the lungs, no air can get into the lungs, in that case no speech sound can be produced, except some one or two in some languages sounds like you know where you do not require lung air, where air in your mouth is manipulated or you can say you know where air in front of your mouth is manipulated, but these sounds are limited few and far between, many Indian languages do not have click as a speech sound, some African languages have it, but by and large no speech sound can be produced, when the vocal cords are in position A, when they are in position B, can we produce speech sounds or cannot we, what is your guess, yes or no, can we produce speech sounds, yes we can produce speech sounds, but they are these sounds are not audible at a distance, I cannot tell you, can you hear me, may be with effort, you know with effort, because you know the context, you know what I am talking about, but suddenly if I start describing the idlies that are sold in Warangal after it has become Telangana, you will not understand, because the context is new to you. So, you know when vocal cords are in position B, then speech sounds are possible, but those speech sounds cannot be heard at a distance. See what is the position, vocal cords are loosely together, partly open loosely together, if there is sufficient air pressure, then air can pass through the vocal cords and in the process they vibrate, they open and close, they open and close, you know they are like this passing air, sense them vibrating and you know that produces noise, speech sounds possible there or not possible there, what do you say, speech sounds possible there and these sounds can be heard even at a distance. So, let us summarize vocal cords in position A that is tightly shut, no or nearly no speech sounds possible, vocal cords in position B speech sounds possible, but come on please, but voiceless cannot be heard at a distance, speech sorry vocal cords in position C speech sounds can be produced and can be heard at a even at a distance that is voiced sounds, please write in speech sounds produced when vocal cords are wide apart, they are called please remember it please remember it for the rest of your life, not only this course, these sounds are called voiceless sounds, it is a contradiction, it is a contradiction how can there be a voiceless sound, if it is sound there is voice, but for the sake of technical description we say these are voiceless sounds, by which we mean that sounds are there of course, but vocal cords are not vibrating in the production of these sounds, these are voiceless sounds, what is the example of a voiceless sound, as in house, as in fan, as in city, as in sun, as in sit or as in sure, as in share, as in shine, these are all voiceless sounds, but speech sounds produced when vocal cords are partly open, loosely together, partly they are sorry, they are what is the opposite of voiceless, voiced, they are voiced sounds, what is the example of a voiced sound, plenty, in each language we have more voiced sounds than we have voiceless sounds, otherwise we would not be able to hear one another, all vowels are voiced, lots of consonants are voiced, what are vowels, voiced sounds, those sounds in the production of which vocal cords vibrate, say for example, keep your finger here and feel the vibration, this is voiced sound, this is voiced sound, but no vibration therefore this is voiceless sound, is it voiced or voiceless, voiced or voiceless, voiceless voiceless, voiced, voiced or voiceless, voiced, that you are able to hear it, that it vibrates here, means that this is voiced sound, if it does not vibrate, if vocal cords are wide apart, then that sound is voiceless, close your eyes and tell me, in the production of voiced sounds, vocal cords complete the sentence, vibrate, in the production of voiceless sounds, vocal cords do not vibrate, look at the other way round, voiceless sounds are those in the production of which vocal cords do not vibrate and voiced sounds are those in the production of which vocal cords vibrate, I will give you 30 seconds, write the definition quickly, voiced sounds are these, voiceless sounds are those, we are not looking at position A, because few, very few speech sounds in any language are produced from position A of the vocal cords, correct, let us move on, how are different kinds of sounds produced, how are different kinds of speech sounds produced, because you know we have more than a few, we do not have only two or three, we do not have only wow wow or wow wow, we have more, we also have wow wow, you know when we see something wonderful, we say wow, when we see the same wonderful thing twice, we say wow wow, okay, but we have more, we also say, when we see an old man and an old woman sitting with a begging bowl on the road, we also say, when we see two people, we say, you know we can say, we can produce a variety of sounds, how do we produce those variety of sounds from the same vocal cords, we said only two kinds of sounds are possible, voiced and voiceless, do you get the question, you know in sciences particularly, answers are not important, because no answer is constant in science, answers keep changing in sciences, sometime we believe that earth was the center of universe, then we believe that the sun was the center of universe, now we believe that neither of them is the center of universe, they are all in constant motion, etc., etc. Answers are important, because they ask new and disturbing questions, they always ask why and how, so the one question here is same airstream, are you with me, same airstream, same organ for forming their functions in the same manner or similar manner, how can this apparatus, how can this machine produce a variety of different kinds of sounds, look at the answer, you know they interact and through permutations and combination, if you have only three letters A B and C and you can combine any with any, then how many combinations do you get, A A A A B A C, then you get B B B A B C, then you get C C C A or A C, you know there are some 10 or 15 combinations can be done with only three letters, similarly you know these are the parameters, what are the parameters, look at the screen, the vocal chords, either they are, either they produced voiced sounds or they produce voiceless sounds, similarly when air comes up to the vocal up to the uvula here, can you see the arrow, yes or no please, when the air comes near the uvula, there is a choice, it can be either oral or it can be nasal or it can be nasalized, so there is that choice, so the second choice is either the sounds are voiced or voiceless or the sounds are oral or nasal or the sounds can be produced with or without obstruction, you see any number of obstructions can occur, the tongue can block air and then release it, the tongue can block air here, then release it, lips can block air and then release it, so through obstruction and through release of obstruction, a variety of sounds can be produced, not only that obstruction at different places, you see obstruction here between soft palate and tongue gives you sounds like ka ga ka, please say it, but now say ta ta, say the entire thing ta ta da da, is it at the same place, once again check, say ka ga ga ga, please say it, now say pa pa ba ba, is it at the same place, do you feel the obstruction at the same place, no obviously not, when you say ka ga ga ga, the obstruction is look at it here between the back of the tongue, here back of the tongue and soft palate, but when you say pa pa, the obstruction is near the lips, both your lips come together, only then do you say pa, but when you say ta ta da da na, say it, where is the obstruction, tip of the tongue and where, no or not heart palates maesh teeth, that is why you know in our system of writing, we call the symbols for these sounds are called by organ of articulation, pa pa ba ba ba are ost habya, labial sounds, ta ta da da na are dental sounds, but look at cha cha, say it, say the entire thing, cha cha ga ga, where do you get these sounds from, from middle, from heart palate, the tongue here you know, the center of the tongue, center of the tongue rises towards the heart palate, blocks air and then you get cha cha ja ja ya, but come further back, when you have ka ka ga ga, where is the obstruction, say cha and ka, please say it alternately, cha ka cha ga, say it, cha cha cha cha cha cha cha cha cha cha cha cha cha cha cha say, do you feel at the same place, do you feel obstruction at the same place, yes or no please, no obvious, you will say loud, let the camera catch, let the rest of the world think that people at IIT are not sick, they are as robust physically as they are perhaps mentally, the obstruction occurs at different places, so please note mentally, you know that the point of obstruction and release of obstruction create, give us two other parameters, what are the other parameters, number one vocal chords, voiced or voiceless, then we have oral or nasal, then we have obstruction or no obstruction, then we have place of obstruction, where does the obstruction occur, then we have manner of obstruction, all obstructions are not the same kind, say for instance when you say pa pa ba ba, both your lips are together, say it, can you say it with only one lip, try and say pa pa with only one lip, not possible right, no matter, you may be an Olympic champion or you may be J. E. E. Topper, but you cannot do pa pa without both your lips, but look at the other thing, when you say it is partial open, there is some gap between the two teeth, correct, you know you can feel air coming out, do it, do it please, so manner of obstruction is differ, also differs, it is not the same, in some places you can have total obstruction, manner of obstruction can differ, either you have either no obstruction, not at all, after vocal chords no obstruction, flows freely or there can be yes obstruction, but even along between in the yes, you can have many different kinds, you can have complete obstruction, you can have total obstruction, when you produce pa, when you produce pa, there is total obstruction unless both your lips come together, unless both lips tightly shut the oral channel, then that sound cannot come out, okay, so you have pa pa ba ba ma, but when you say sss, azz, or it is not total obstruction, it is partial obstruction, okay, it is partial obstruction, the part of the passage is constricted, it is so narrow that the air goes, but air goes with friction and in the process there is noise, okay, so another parameter is place of obstruction, sorry manner of obstruction and there manner of obstruction can also differ, either there is please complete, no obstruction or there is yes obstruction, yes obstruction can also be 2 or 3 different kinds, either there is complete closure or there is partial closure, so you know these combinations give us different kinds of sound, are they voiced or voiceless, are they oral or nasal, are they obstructed or unstructed, are they partly obstructed, fully obstructed, ask the questions once again, are they voiced or voiceless, are they oral or nasal, then complete or partly obstructed, okay, then there is release of obstruction, obstruction alone is not enough, if you keep your mouth shut there will be no noise, there will be no speech sound, that is the position of either yoga or quarrel between man and wife, okay, speech sounds happen because obstruction is released, obstruction is opened, okay, so obstruction can be released in one of the two manners, okay, either it can be released suddenly, sudden release or it can be gradual release, either it is sudden release or it is gradual release, sudden release such as you see complete closure, both your lips are together and your cheek is puffed and you say pa, ba, ba, but look at the other thing, you know in English particularly, it sound like shh, as in church, as in judge, there is complete closure, the middle of the tongue here rises towards the heart palate, completely blocks it and then slowly it lets it go, church, judge, bench, chair, cheer, okay, in our languages it is not so gradual, but in English it is gradual, the total obstruction is released gradually, slowly, not sudden, not there is sudden explosion, okay, so let us now revise the parameters which help us get sounds, please look at the screen if you like or close your eyes and say, we get different kinds of sounds because vocal cords are either, you know, sounds are either voiced or voiceless, either they are oral or nasal, either they are obstructed or unobstructed, either they are obstructed at the lips or obstructed at tongue or back of tongue, middle of the tongue, either they are totally obstructed or they are, either they are suddenly released or gradually released, please write quickly, what are the parameters that give us these sounds, these are the parameters, voiced or voiceless, oral or nasal, obstructed or obstructed, tongue or lips and gradual or sudden, okay, these combinations together, okay, give us a variety of speech sounds with which there is no language in the world which needs anything more than this, with the interaction of these parameters we get different kinds of speech sounds, let us come to something interesting, what is the first major class of sounds, what is the first major class of sounds, the first major class of sounds, you know, first classification, okay, as in the animal world, so in the world of speech sounds we make classification, broad classification, major classification and then sub-classification and sub-sub-classification, you see at this institute we can say there are two major classifications, faculty and staff versus students, then among the students we will make further classification, undergraduate, post-graduate, and the undergraduate we will make further classification, okay, aerospace or department wise or hostel wise, okay, girls hostel, boys hostel, okay, there may be boys who live constantly elsewhere just as there may be students who do not live on the campus, but you know we make some broad classifications in this manner, similarly in speech sounds as well we make classification, the first major classification is please write vowel sounds, what are vowel sounds, vowel sounds or those sounds please write, vowel sounds or those sounds which are vowels are, vowels or vowel sounds are number one, what do you say, voiced or voiceless, voiced, I would just say keep your finger here and follow me, say I who constantly vibrates, so first characteristic of vowel sounds is number one, they are voiced, okay, second, are they oral or nasal, say keep your hand here and see where air comes from, say I who, do you find air coming from your mouth or from your nose, mouth, so second characteristic is they are oral, third characteristic are they obstructed or unobstructed, they are unobstructed, once they cross the vocal chords, once they send vocal chords vibrating after that there is no obstruction anywhere in the production of speech sounds, they pass through the oral passes, you see here is the vocal chords, they cross it, they leave it vibrating and then they go through the pharynx and then through the oral passage, through the oral cavity, they flow freely and that is vowel sound, so the third characteristic of vowel sound is they are free or un, please give me the word unobstructed, lovely, you are great phoneticians now, okay, I expect to have some ten great phoneticians from this class, now please what are the characteristics of vowel sounds, vowel sounds are voiced, oral and unobstructed, close your eyes, vowel sounds are voiced, oral, unobstructed, okay, there is no exception to this rule, open your eyes now, there is no exception to this rule that all vowel sounds in any language of the world be they Telugu, be they English, be they French, be they Vietnamese, no matter what, all vowel sounds in all human languages have these characteristics, what are they, they are voiced, oral and free, unobstructed, now comes a bigger, another question, if they are all the same, then what is the difference between a and e, what is the difference between e and u, okay, they are both vowel sounds, how do we get different kinds of vowel sounds, how do we get a, e, u, a, o, i, o, all of these vowel sounds, you know, in Telugu you call them swara, correct, in Sanskrit we call them swara, how do we get different kinds of vowel sounds, what parameters work there, if you look at this area, all vowel sounds are produced from this area, can you see the arrow moving, can you see the arrow head moving please, they are produced from this area, from near the alveolar ridge to the middle of the tongue and back of the tongue to the soft palate, they make some kind of a trapezium, some kind of a trapezium, okay, from here to here, from near to the alveolar ridge to the middle of the tongue and then from the soft palate to the back of the tongue, all of these vocal vowel sounds are produced, if you raise the tongue slightly you get e, say it, but if you open your jaws lower the tongue then you get a, if you open it only a little less then you get a, if you open it more then you get a, begin again, open it slightly, you get e, okay, that way you know, you really you know do not get bored, so you know when you say e the opening is limited, e, open it more and you get a, still more you get a, still more you get a, you see the degree of opening the very, now come backwards, okay, you say e, then you say a, say e, when you say o, it is further back on the tongue, so these parameters you know from here to here and from here to here, they look like a trapezium, okay, please copy it quick, this is the idealized diagram of the vowel area, okay, idealized, do not go with a torch and look into your friend's mouth and see, I want to see vowel trapezium in your mouth, okay, God did not create such stupid things there, okay, but generally you know this is the geometry of the area, this is the trigonometry of the area from which we produce vowel sounds, you know, some sounds are at the near the front of the mouth, some vowel sounds come from near the back of the mouth, just as some sounds come from extreme closure or the you know jaws are raised or they are produced from the extreme opening, jaws are lowered, together this area, the you know the diagram of this area in idealized situation, not in the real situation, real life is much more complex, but the parameters are the same, okay, here for the classroom purposes, this is the idealized situations, what is a vowel trapezium, vowel trapezium is an idealized description of that area in your mouth, in my mouth, in our mouth from where we produce vowel sounds, please write, vowel trapezium is an idealized representation of the area from where we produce vowel sounds, area in our mouth from where we produce vowel sounds, am I clear to you, say yes or no, please, lovely, you are angels, okay, is that clear ma, sure, okay, now what are the parameters in vowel trapezium, okay what are the kinds of things we look, you know, vowel trapezium can have these parameters, number one, please look at the diagram, you are either at the front of it or at the back of it, either it is high or it is low, some in many books in place of high please write, you will find close, many books say close, here they say close, both jaws are closed together, when you say ee, say it, they cannot come closer, if you bring further closer, the mouth will get shut, so begin with aah, okay, and close it as I do, aah, so there will come a point beyond which if you shut, there will be no sound, there will be obstruction, similarly there is a point beyond which you cannot open, you start with ee and reach aah, you cannot go further, nobody can pull your, you know, tongue further than or jaws further than this, so these are close, this is open or in many book you find it high and this is low, does not matter, use whatever level you like, similarly this is vertical axis, this is vertical axis, on the horizontal axis this is, what is this, this is front, on the horizontal axis this is front and therefore this is back and therefore this is central, okay, in between, in between there are many positions, they look at aah, when you say aah as in egg, when you say ee jaws are closed, when you say aah jaws are open, okay, but when you say aah it is in the middle, it is somewhere here, it is somewhere here, so people take lots of other cuts, okay, now to describe the vowel sounds in all languages of the world, to describe the vowel sounds in the languages of the world, people have thought of these parameters, what are those please write, either they are front or back or they are high or low, close or open as you like, alright, say for example a vowel like ee is close, okay, but another vowel like, I am using some phonetic symbols, you will find them in the books or you know you can learn them, I can give you link, I can, I think I have given you all some links already, okay, so they are both vowel sounds, but they differ from each other, this is a vowel sound as much as this is a vowel sound, they differ from each other in only one respect, that is this is high, this is high, this is low, or in other words this is close and this is half open, not fully open, but half open, similarly you know compare this with o, okay, this is front, but this is back, there can be another vowel as in aah, okay, as in about, as in about, as in about, as in away, this is right in the centre, it is neither fully open nor fully closed, it is neither front nor back, it is in the centre, so there can be each you know of these different positions which help us describe vowels, but at the extreme edges, at the extreme edges here, here, here, here, here, at the extreme point you know, phoneticians have decided that with reference to these points other vowels can be described, therefore these extreme points are known as please write, what are these extreme points, these are cardinal vowels, cardinal vowels are extreme sounds, nobody has, no language has those extreme sounds, but it is like north pole and south pole, with reference to these two poles, you can describe the rest of the earth, okay, similarly with reference to these points, okay, it is not the case that in any language you have a vowel sound which is produced from extreme front and extreme high or extreme close or extreme opening or extreme back, they are somewhere here, they are somewhere here, but with reference to these points you can describe them, but these imaginary vowels these imaginary vowels which do not exist in any language, but which help us describe existing vowels please write are called cardinal vowels, what are cardinal vowels, cardinal vowels are imaginary vowels at the extreme of the trapezium, okay, we will finish in a few moments, this is the shape that cardinal vowel look like, okay, if you draw a diagram these are the cardinal vowels, okay, look at the letters in black, they are E U A O A O A A, okay, there are some letters in red, I will tell you in a minute, what is the difference between E and U, they are both high, but one is front, the other is back, there is another difference, when you say E your lips are spread, say it E, but when you say U your lips are rounded, okay, so shape of lips please write, the shape of lips also plays an important role in the production of speech sounds, in the production of vowel sounds, okay, height of tongue, part of tongue and shape of lips, production of vowel sounds is influenced by height of tongue, then part of tongue and then shape of lips, in other words it can be either high or low, okay, as in E or A, when you say E it is high or closed, when you say A it is open or low, okay, part of tongue, when you say E it is the front of tongue, but when you say U it is back of tongue, when you say A it is the center of tongue, third factor is shape of lips, shape of lips can be either flat, look at the screen, when you say E, can you round your lips and say E, try it, can you round your lips and say E, okay, we cannot, okay, similarly you know when you say U, when we say U our lips are rounded, can you spread your lips and say U, can you spread your lips and say U, no we cannot, so that is the third factor, okay, come back to it, the vowels in red show those minority sounds where front vowel is rounded and back vowel is spread, in most languages of the world, okay, E is produced with spread lips, U is produced with rounded lips, but it is possible, you know, because in nature, in God's world anything is possible, we say people have five fingers, but some people have six fingers, we say people have 32 teeth, but some people have 34 teeth, okay, right, it is possible, you know it does happen, usually people are born one at a time, but sometimes you can have two people coming at a time, okay, they are inseparable friends, correct, so in nature freaks are possible, similarly here it says that in that case, if this vowel is going to be rounded, then the other vowel will be spread, okay, the opposite of, you know, the pair is front and back, what are the pairs, front and back, close and open or high and low, similarly rounded or unrounded, please write, you can have rounded or unrounded, okay, these are the pairs, this is how vowels are described, either they are front or back or they are high or low or they are unrounded, okay, to summarize now, all vowel sounds are, what are the characteristics of vowel sounds, all vowel sounds are voiced, oral and free, okay, what is a vowel trapezium, it is an imaginary area which describes what, which describes the area in our mouth from where we produce vowels, how do vowels differ from one another, either they are front, either they are front or back, either or they are high or low, close or open or they are rounded or unrounded, great, you are, you guys are, you know, sure, thank you, have a good evening.