Expressive Transducer

The Expressive Transducer, and What Babies Hear • In Mysak's model, we described the Expressive Transducer in three parts: the Motor, the Generator and the Modulators. • Motor: This refers to the source of energy for speech, and if anything is going to happen muscles must be involved. Nowhere is this more true than for the speech act. • The first muscle we may all think of is the diaphragm. Actually, this is a domed shaped muscle when relaxed. • It separates the chest cavity from the abdominal cavity. When it is tensed, it flattens out, creating a partial vacuum in the chest cavity. Air will rush in through the nose, trachea ("wind pipe") and lungs to fill the space. • This is inhalation and as you can see it is an active process. There are many more muscles involved, however, in inhalation than just the diaphragm. When breathing for life, inhalation is active involving many muscles and exhalation is passive. • There are muscles between the ribs, and over the shoulders, some extending from the back of the head. • When the diaphragm flattens, these muscles combine to expand the ribcage. Even muscles low down in the back may be called upon to stabilize the spinal column. • Think of the massive timing process that the brain must habitually orchestrate to repeatedly coordinate all these muscles. • In contrast to inhalation which is so active and complicated, exhalation is the easiest thing we ever do (unless we have emphysema). • To breath out we simply relax and the elastic nature of the diaphragm returns it to its normal dome shape (helped by the push of the viscera which were compressed during inhalation). The chest cavity collapses helped by gravity. All this forces the air out. It is a totally passive process. When breathing for speech, exhalation is highly controlled, requiring special neurological circuitry which humans posses. • But when breathing for the purpose of speech, the exhalation process also becomes active and even more complicated. Now the breath is forced out through the vocal folds in a carefully controlled flow. • We do this effortlessly, partly because we have a large cadre of nerves devoted to the process. This is a genetic inheritance. "Ed" the "talking horse" and even "Koko" the signing gorilla could not really control the breath stream well enough to produce speech as humans do. • If you are not familiar with "Ed" check the notes. • Sometimes the process is pathologically disturbed. Cerebral Palsy children may have problems in coordinating the flow of speech and may find it difficult to get more than one word or sentence to a breath if at all. • Even some stutterers find the processes disrupted and the lack of coordination in breathing process is quite visible if not uncomfortable to watch. The Generator is a mechanism to produce sound , which is required for speech. • The purpose of respiration for speech, is to move air. Of course there are other muscles not involved with moving air which must nevertheless be coordinated with the breath stream. • These are the muscles of the soft palate (velum), the tongue, lips jaw, and the larynx. The function of the larynx, of course, is to generate the sounds for the vowels and many consonants. • Generator: The whole purpose of moving air is to create sound which can transmit a symbolic signal. There are a number of locations around the body, and particularly in the oral track were sounds can be made. Tapping with the feet is one example. "Donald Duck" talk using the back of the oral cavity is another. Using the feet takes considerable energy, and it's hard to find a time when the feet are not precoccupied with walking or standing. There are two passages leading from the oral cavity--one for food (Esophagus) and one for air (Trachea). • "Donald Duck" talk is very limited in its range of pitch and loudness, and constricts the tongue in its production. • Ironically, our generator, which is very effective and efficient comes to us perhaps through serendipity as a side effect of nature's attempt to solve a serious structural problem. • Visualize this. Here we have the oral cavity which is used for two purposes: Food intake and Air Intake. • The structural problem is this."They" placed our air intake tube (the trachea) in front of the foot intake tube (the esophagus). That means that every time you take a bite to eat, you must pass the food over the trachea. • Should a tiny morsel (like a sliced carrot or even a vitamin pill) fall into the trachea, we may have just five more minutes to live--and not a particularly fun five minutes either! If liquid or food gets down the wrong tube (the Trachea) we may get pneumonia or worse yet, quick asphyxiation. • And even if it's liquid, you might not choke but you then become a good candidate for pneumonia. And we swallow liquid (saliva) almost constantly. • I once challenged the class not to swallow for the entire period; and after 15 minutes we all looked like a pack of rabid writhing wretches. Because the class was mostly girls you could say that we were a "room of rabid writhing retching wenches." • Sorry about that, I just like tongue twisters. • Obviously most of us have not choked on our food nor gotten pneumonia. That is because nature has built in some safeguards. • At the top of the trachea, which is a cartilaginous ringed tube, is a valve "box" which can close the entrance to the tube. This is made up of two cartilaginous sections: the cricoid and the thyroid cartilage. The Larynx (not to be pronounced "Larnyx") is a valve system at the top of the Trachea to keep food out. • The cricoid cartilage is like the final ring of the Trachea, only somewhat more complex. The Thyroid cartilage is shaped like a shield attached to but placed in front of the cricoid cartilage. This is what people are seeing when they observe the "Adam's Apple." • This structure is commonly called the voice box, but more correctly it should be labeled the "Larynx." Caution, do not call it the "larnyx!" This can cause a major stroke in some speech professors. In the Larynx, the vocal folds open and close to let air pass and to keep food from falling down the Trachea. • Stretched across the opening of the cricoid cartilage are the two vocal folds made mostly of connective tissue. They are always closed in front at the point where they meet, but swing open and shut from the other end. • The rapidity with which these folds can open and close (an alternating movement called diodochokenesis) is unparalleled in the body. When we swallow, the vocal folds close snuggly. There is actually another point of closure just above the folds called the False Vocal Folds. When the vocal folds are shut and air if forced through, they will vibrate and produce a sound. • The false vocal folds are not as well controlled as the real ones. But I have had at least one student who used them to vocalize. It was a real harsh sound and a problem for him because he couldn(tm)t use his regular folds. • Other mechanisms to keep food from being swallowed include the raising of the larynx during swallowing. You can actually see this on someone else as the "Adams Apple" goes up an down. • There is a cartilaginous slide over the entrance called the epiglottis, and folds along the side of the entrance to the larynx to catch particles of food. There is also a liberal system of cough reflexes to expel particles of food. Together, these safeguards work pretty well most of the time. • The serendipitous part for speech is that when the folds are shut and air is forced through, sound vibrations are produced. The only changes in sound we can make at the level of the larynx is to raise and lower the pitch and loudness. • The action of the vocal folds is much like that of the lips when we make the "Bronks Cheer." We hold our lips together firmly and force the air though to make them vibrate, albeit with a sputtering sound. • The vocal folds are much smaller, of course, and capable of faster and finer vibrations. The result is the beginnings of voice. Not that it sounds all that great, at that point. Originally, it is really a rather pitiful squeak. It is left to the resonators to shape the vocalization into something we would recognize as a human voice. • • The only changes we can impose upon sound at the level of the larynx are to raise and lower the volume (which is really a matter of breath control) and to raise or lower the the pitch. The latter we do by changing the tension of the vocal folds. • Typically, the mass of the vocal folds remain constant. However, there is a rapid increase in mass for boys particularly, during puberty. When the vocal folds are abused they may swell, which causes a drop in the pitch of the voice. • Also, when we get a cold, the irritating secretions generated by the sickness, or the wear and tear on the vocal folds created by the frequent coughing spasms may cause them to become swollen. • The increased mass gives rise to a deeper fundamental tone and hence, a deeper voice. We then say that we sound like we have a "frog in our throat." • Yelling a lot can cause the same problem. • If yelling persists it can cause calluses to grow on the folds. These are called vocal nodules. Vocal Nodules diminish the naturally smooth seal between the folds. This requires more energy to produce a tone and causes even more damage to the folds. • Eventually the calluses become as hard as fingernails and are difficult to get rid of. The voice quality is typically unpleasant--low, harsh and breathy. The greatest threat to the health of the vocal folds is smoking. • Vocal abuse and its consequence of vocal nodules can be a major problem for young singers. If they have not learned proper techniques, they will often require more intensity to sing than is typically necessary and healthy for the folds. Tragically the drive to keep performing eventually ends in the inability to keep singing at all. • The greatest single threat to the vocal folds, however, is smoking! The caustic nature of cigarette smoke with it cyanide, and many other poisonous gases acts to suppress the immune system. • This in general creates more frequent sicknesses and slower healing processes, and eventually a very high risk for cancer of the larynx. What may be worse to some people, of course, is that smoking causes deep creases in our favorite passport--the face. • The good news about laryngeal cancer is that it is easily detected. The pitch of the voice typically drops noticeably which eventually catches the patient(tm)s and the doctor(tm)s attention. A person who has his/her larynx removed is called a laryngectomee. • The bad news is the threat to life that laryngeal cancer poses because of its proximity to many lymph nodes in the neck. Should the cancer break through to these nodes it could be spread throughout the body. • The good news is that this can be totally prevented in many cases by totally removing the larynx (laryngectome). • The bad news is that once this is done, there is no valve at the top of the trachea to prevent food and liquid from spilling into the Trachea. • The good news is that this can be remedied by attaching the upper end of the trachea to a hole (stoma) in the neck. The patient then breathes though this hole in his/her neck. Now, there is no connection from the lungs to the mouth. • The bad news, of course, is that there is now no vocal folds nor air flow to produce sound for speech. Its hard for any one to imagine the isolation that people experience when they can't speak. A laryngectomee has no voice, and must use an artificial larynx or esophageal speech to communicate. • Writing is not a good substitute for conversational speech. Sign Language is, but more often than not, the community of the patient does not know Sign Language and is reluctant to learn. • The good news is that there are alternatives. Since it is the generator that has been lost, if we can find another, we are back in business. • We have already mentioned "Donald Duck" talk with the back of the oral cavity. • A more viable source of vibration is the esophagus. Everyone has "burped" sometime in their life. If they "mouthed" a word as they did so, they could produce an audible word or two. • Esophageal speech is based on the same principle. Only small amounts of air are injected by the tongue into the top entrance of the esophagus where it is forced out again with a vibration. Esophageal speech takes time and effort to learn, and the artificial larynx sounds mechanical. • The bad news is that, as a passport to society, there is much to be desired. In the notes below I give an example of esophageal speech. When I do this in class, many students report they feel ill. • The good news is that with practice you can improve. In the Movie QB VII, the actor who played the Judge was a laryngectomee and was using esophageal speech. I highly recommend renting the video to observe this actor. Its an excellent movie, too. • The alternative to esophageal speech is to obtain an artificial source of vibration. Battery operated oscillators can be placed on the throat or cheek to cause the oral cavity to resonate. • If the words are then "mouthed," audible speech is produced. An advantage of this over esophageal speech is that longer sentences can be produced, and little practice is needed. The disadvantage is that it sounds very mechanical. Juvenile Pappiloma is an aggressive growth on the larynx of some young children that requires medical attention. • Actually, the best advise is to not smoke. The human voice without question the best of all passports. Not that people don't get laryngeal cancer form other causes. Sometimes it is unavoidable. • But every time I see a teenager "light up," I feel sad because somehow I feel that that should have been avoidable. The message should, but is not getting through. • Juvenile Pappiloma is another type of growth on the vocal folds that afflicts some young children. Its like having warts that grow very fast. Although it effects the voice, the major concern is breathing. • The growths must be surgically removed many times. Fortunately, they frequently cease to be a problem after puberty. A series of resonating air chambers above the larynx alter the overtones to create the human voice. • There are three major resonating cavities above the larynx: The Pharynx, the Nasal Cavity and the Oral Cavity. • The pharynx (not the be pronounced -pharnyx...) is the area directly above the the larynx, in the back of the throat up to the oral cavity. • It is not typically changed during speech, although under conditions of overall body tension, it can be constricted. • Modulator: The complex tone produced by the larynx alone does not particularly sound human. It is the action of the resonating air chambers above the larynx that shape the sound into its human form by screening, and hence modifying, the pattern of overtones. • Air in an open area does not typically resonate, but in an enclosed areas, such as a bottle it will. Hence, the cavities in the air channels leading to the larynx can serve as resonators. The Pharynx and the Nasal Cavity are two resonating cavities that shape the sound produced by the Larynx. • Constricting the pharynx typically degrades the quality of the resonation. However, voice impersonators, like Rich Little, do amazing things by bring this resonator under voluntary control. • Others of us find an improved quality of voice when we learn to relax the muscles around the pharynx. Bing Crosby was probably the most relaxed man on earth when he sang. • The Nasal cavity is well known to anybody (everybody) who has had a head cold and has experienced the discomfort of having a stuffy nose. Try to say under those conditions the phrase ("Eminent Women.") It comes out ("Ebidedt Wobed"). • Ironically, in English, there are only three sounds that use nasal resonance (i.e., are produced with the soft palate {velum} open.) Only three sounds in English use Nasal Resonance.: "m," "n," and "ng." • The only three nasal phonemes in English are: "m" as in "mam," "n" as in "non," and "ng" as in "-bong." • If you prolong those three sounds while placing your fingers on the side of your nose, you can feel the resonance. Try it and then alternate making a non nasal sounds (i.e., any vowel or other consonant). • Although there are only three nasal phonemes, they occur in speech with an especially high frequency. • Sometimes if a child(tm)s movement of the velum is sluggish, the sounds on either side of a nasal phoneme may also acquire a nasal resonance. This is called assimilation, and would occur in a word like, "man;" but not in "pat." • When vowels are nasalized, they are still recognizable, although the resonance may sound a little whiney. • The Oral Cavity is the major Modulator of the three resonating cavities. • When consonants other than -m, n and ng... are nasalized, they become unintelligible. This is because the air pressure needed to make a consonant escapes through the nose. • The Oral Cavity is the most amazing of all resonators. It is a modulator in that it can easily change in many ways the nature of the overtones generated by the larynx. • Using the articulators (particularly the jaw and the tongue) the size of the air masses in the oral cavity can be easily and quickly modified. • This is one major advantage of oral speech over Sign Language. The latter requires considerable effort (relatively speaking). My class on campus, which is three hours long, requires at least two Sign Language Interpreters. One only for the whole three hours would be a good candidate for Carpal Tunnel Syndrome. The Oral Cavity can produce phonemes with a minimal expenditure of movement and energy. • So relatively minimal is the movements for speech, that I have never heard of a single professor coming down with Carpal Tunnel Syndrome of the Tongue. • To the contrary, the tongue is the strongest muscle in the body (inch for inch), and has a large quantity of neural tissue in the brain devoted to it's control. • It can assume a number of different shapes in the oral cavity with a minimum expenditure of energy. • For example it can arch in the front, middle or back; and can at the same time be raised or lowered. • As the air masses around the tongue in the oral cavity are changed (thus changing the natural frequencies) their screening potential for overtones changes. Each change in the pattern of overtones creates a new vowel sound. • Actually, that is only partly true, because we do not really produce discrete phonemes. What do we do? Actually, speech is not a series of discrete phonemes, but a continuous modulated flow of vocalized sound. • What we produce in speech is a continuous flow of modulated frequencies. You get a notion of how this sounds when you play speech backwards. • It is in truth, the listener, who superimposes his/her own template (expectancies) of phonemes on perceived running speech, that turns the continuous flow into apparent sequences of discrete phonemes. • That's one of the factors that makes foreign languages so difficult to learn for adults. • As an English speaker, when I hear Japanese, I automatically try to fit the stream of sounds into English phonemes. As a result I will fail to hear many important phonemes that are not in the English Language. • But what do babies, who have not had time to develop a template of phonemes, hear? They simply hear the continuous modulated flow of speech. How, then, do they develop the template? Babies do not perceive phonemes, but instead can hear all of the distinctive features that build the phonemes of every language. • Babies hear no phonemes in those first few months of life. • Ironically, however, their hearing is fully functioning by the time of birth. In addition, they possess some rather amazing auditory perceptual skills, apparently wired in before birth, which make them in some ways superior listeners to adults. • Whereas they don't hear the phonemes of a language, they can perceive the building blocks (the distinctive features) of all languages! • It is believed that the neural connections for distinctive features that are reinforced by the environment are strengthened, while those that are not stimulated are lost. • Hence in adulthood, my ability to hear the distinctive features that contribute to phonemes of languages not spoken in the home when I was a child, is lost. • A good example is Voice Onset Time. Voice Onset Time is a good example of a distinctive feature that babies perceive, but we as adults may not. • In English, if we start the laryngeal tone exactly at the beginning of the "P" sound, it becomes (is perceived as) the "B" sound. If we delay progressively longer in small increments the beginning of the voice (voice onset time), there is a point in time that it would become the "P" sound. If a line under the wordd represents the beginning of the voice, it would look like this: • BIT • PIT • Because as babies, we were exposed to verbal experiences in which those phonemic boundaries were used, we can discriminate these sound differences today. • But there are some languages that include a Voice Onset time before the beginning of the consonant: • BIT • _BIT • If the two words above were spoken and heard by a speaker of such a language, the two would be heard as different words--although to us they would sound and be the same. It is advantageous to have speakers of other languages talk to babies who are not high risks for language delay. • This is certainly one good argument for having family members who speak other languages talk to babies while they are young, to reinforce those neural tracks. This of course applies to babies who are not high risk for language delay. • I was asked in class if it would be beneficial to play language records in the presence of the child when they are babies. This would be an interesting topic for a doctoral dissertation for someone who has a baby and doesn(tm)t mind the background clamor. • Please let me know the results of your findings! • So what are those distinctive features that babies hear. There are books written on them. If you want to punish yourself severely for some indulgence, check one out on a Saturday evening and try to read it. In comparison, it makes a plumbing catalog seem like a romantic novel. • To give you a small flavor of what it is all about, we will limit ourselves to a discussion of just four each for vowels and consonants. The Place of Constriction of the air flow through the vocal tract is one distinctive feature for consonants. • • The four Distinctive Features for Consonants, that I have selected to discuss, include the Place of Articulation, the Manner, the inclusion of larynx (plus or minus voicing) and the inclusion of nasal resonance (plus or minus nasality resonance). Place of Articulation. The hallmark of a consonant is the constriction of the airflow somewhere on the vocal tract. This constriction creates a noise, as we discussed earlier. o There are certain locations along the oral tract (phonemic boundaries) where constriction has the potential to create a different phoneme. These locations can be described from front to back. Different languages select some boundaries that are the same and others that are different. o In English the most forward constriction boundary is the two lips (e.g., the bilabial "B"). The place of constriction can be described in terms of locations proceeding from front to back in the vocal tract. o o o There is, of course, the potential for a labio-nasal sound which no one has mastered yet. If you can master it you are eligible to receive the Grand Prize offered as an incentive in this course.* The sound is made by flinging the lower lip over the tip of the nose while expelling air through the mouth. Do not try this at home, however, but only near a medical setting. *(The Grand Prize is: A full body size autographed photo of your instructor which can be placed in the living room.) Getting back to English, and reality, the next place of constriction would be the lower lip on the upper teeth (e.g., the labio-dental "F"). This would be followed by the tongue between the teeth (e.g., the inter-dental "TH"); the tongue on the gum ridge (alveolar ridge for "T" and "S"); the tongue a little farther back on the palate (for "SH"); and the back of the tongue on the soft palate (velum for "K"). The baby is capable of perceiving the constriction boundaries of English and all other languages. o The farthest back you can go in English (and in any language as far as I know) is the glottis (the space between the vocal folds) to produce the "H" sound. Here we create air friction through the partially open folds, much as we do when we whisper. o In other languages, there are many intermediate locations for constriction that we don(tm)t have in English. An interesting one to me is the "X" sound in Russian, which to me sounds like "H" but is made farther forward. There is another one in Hebrew, which I wont even attempt to explain but it sounds to me like "Hkghshghghksh." I believe I did make that sound correctly by serendipity once during a heated discussion with my wife who was choking me at the time. o o The baby, of course, is capable of hearing all these boundaries, but in time will retain only those that are used in his/her presence. In vocalizations, back consonants appear first during the reflexive stages, but front consonants appear first in the voluntary stages. o In terms of sound production, the baby during the initial reflexive stages, of cooing and babbling, when there is little control of the articulators, will produce mainly the back consonants like "K," and "G." o This is not surprising since tongue tip control is not gained until later. Plus, the tongue is relatively large for the size of the oral cavity. At about six months of age, however, considerable voluntary control of the articulators is achieved. The child enters a new stage of vocalization called Lalling, which we will discuss later in another section. Under these circumstances the sounds we hear at first almost exclusively are the front consonants like "M," "B," and "D." o o o It is not surprising that the names of significant others to the baby in many languages are words that begin with front consonants, like "Mama," Dada," and "Baba." The Manner of Articulation is a second Distinctive Feature for Consonants. • The Manner of Articulation: Sometimes the point of constriction for two or more phonemes is the same. What differs is the manner in which they are made. Let me give three examples: Plosives, Fricatives and Affricates. o o o For Plosives, the air flow is completely blocked, thus creating a build-up of pressure. When the constriction is abruptly removed, the air escapes in with mini explosion (e.g., "P," "T" and "K"). For Fricatives, the constriction is only partial, thus creating some pressure build-up while at the same time letting air escape with a turbulence that creates a noise (e.g., "F," "TH," "S," and "Sh.") An Affricate is a phonemic "sandwich," that it is produced by both of the distinctive features, one top of the other. There are only two in English so we will use them as examples. The first is the first (or last) sound in the word "church." The addition of a tone from the Larynx (+Voicing) to the noise of a consonant provides a third distinctive feature. o The "CH" sound starts out as the plosive "T" and ends up as the fricative "SH." o Sometimes when a child has a lateral lisp for the "SH" sound (i.e., it sounds more like "SHL"), he/she will nevertheless make the "CH" sound correctly. When this happens, the "SH" part of this affricate can be use to teach the child to make the "SH" sound correctly. o The other example of an affricate is the first (and last) sound in the word "judge." This starts out as the plosive "D" and ends up as the fricative "Zsh" as in the word "vision." o • Voicing: Sometimes both the point of constriction for two or more phonemes and the manner are the same! What differs is whether or not a larngeal tone accompanies the air turbulence. The only difference between "P" and "B," for example, is that the latter includes a tone from the larynx. These pairs of sounds are called cognates. Nasality, a fourth distinctive feature of consonants, is used in only 3 phonemes in English: "M," "N," and "Ng." o Put your hand on your larynx and say "P" and "B" several times in succession. You can feel the vibration of the larynx on the "B" sound. Which one of the pairs of following cognates are voiced (have +Voicing): o PB DT FV SZ o o o o GK o o Which of the two affricates that we discussed has +voicing? The answers are "B," "D," "V," "Z," and "G." The affricate in "judge" is also voiced. • Nasality: Unlike French which includes nasal resonance in some vowels, no vowels in English include it. No consonants can be made either nasality with the exception these three: "M," "N," and "Ng." • There are many more distinctive features for consonants, but we'll leave these for all those linguistically brilliant babies to discover, and for those few lifeless speech pathologists or linguists to describe in a book. The place of articulation for vowels refers to the arching action of the tongue to produce front, mid or back vowels. • • We will switch now to some (four) of the more interesting distinctive features of vowels. The four I have chosen to discuss are: The place of articulation; the height of articulation; tense versus lax vowels; and lip rounding. The Place of Articulation: This sounds suspiciously like a feature that we discussed earlier for consonants. But vowels don't involve the constriction of vocal air flow. In this case, place of articulation is referring to the contour of the tongue. o The tongue is capable of arching in different ways to partition the air masses in the oral cavity. o The vowels that are produced when the tongue arches toward the front are called front vowels. An example would be the vowel in the word:  "beat." o When the tongue arches toward the center, we have mid vowels produced, such as in the word:  "up." In vocalizations, front vowels appear first during the reflexive stages, but back vowels appear first in the voluntary stages. o When the tongue arches in the back we have back vowels. An example would be the vowel in the word:  "soon" o o o During the period of reflexive vocalizations for the baby, the vowels that will be heard most frequently are the front vowels. This makes some logical sense since the back of the tongue would occupied in the act of constricting the air flow for the consonants. Later as the child gains control over the articulators and voluntarily produces sounds, the back vowels will be heard initially more frequently. This is quite prevalent in early words like "Mama," and "Papa." The tongue raises and lowers to produce an array of front and back vowels. • The height of articulation: Not only does the tongue partition the air masses to produce front and back vowels, but it can be raised or lowered in the oral cavity to further modify them. o Thus a full array of front vowels can be produced from high to low as follows: "beat"  "bit"  "bait"  "bet"  "bat" For the back vowels, the array would be from high to low as follows:  o      o "soon" "stood" "sow' "saw" "sod" Although it is not absolutely necessary, most people drop their jaw when producing low vowels to provide more room for the tongue. This has considerable value in the process of speech (lip) reading. The position of the jaw will drop for low vowels to facilitate the movement of the tongue. o In lip reading the viewer has no way of knowing what the tongue is doing (because it is not visible). Hence, the only way that he/she can discriminate between words like "beat" and "bat" is to deduce the sound by observing the movement of the jaw. o I might add that Speech reading is not just for the deaf or hard of hearing. o We all use it when we are listening in a noisy environment and can(tm)t clearly hear the speech sounds. o Then our gaze will subtly shift (often, without our even realizing it) from focusing on the speaker's eyes to observing his/her mouth. Ironically, in these situations, our "hearing" seems to gets worse if the lights are dimmed. Tense versus Lax: A very subtle distinctive feature is the degree of tenseness exhibited by the tongue when producing certain vowels. o • For some vowels, the tongue is more relaxed than for others. • o Both the highest front and back vowels, for example, are Tense. Some real examples are:  "Lean" (front) & "Luke" (back). o The next lower vowels are less tense or Lax. Examples are:  "Lynn" (front) and "Look" (back). o The mid vowel also, as in "up" is also Lax. o This is nothing as adults that we can readily feel or see. The muscle tension is orchestrated at a subliminal level during production. Lip Rounding: Take a class in speech improvement and you will spend a lot of time practicing to round the lips when producing certain vowels. o Paradoxically, if you take a class in Ventriloquism, you will spend a lot of time practicing NOT to round the lips for the same sounds! How come? o Lip rounding is not essential for the production of any of the vowels. But it does have a place in vowel production. Lip rounding is more essential for lip reading than for sound production. o In English, there is a general tendency to round the lips for the back vowels. Try it and see...      "soon" "stood" "sow" "saw" "sod" o Alternately, we relatively draw the lips back for the front vowels. Try that too: "beat" "bit" "bait" "bet" "bat" Now for a fun experience say the back vowels (starting with "soon,") but make your lips draw back, as in a broad smile. It feels funny but with a little practice, you can do it. Try the front vowels above (starting with "beat") but purse your lips forward (i.e.,round your lips).      o Lip rounding is an important visual component in the perception of speech. o Where lip movements become really important is in the process of lip reading, which as I said, we all do. In a noisy environment we can tell from the lips whether the person said "beat" or "boot." If he rounded the lips, we know he said "boot." o And if he rounded the lips and dropped the jaw simultaneously, he probably said something like "bought." o Now, what happens if he says the word "bought" but doesn(tm)t purse the lips or drop the jaw? o The word comes out fine but it is definitely difficult to lip read. o If he says the word with no lip or jaw movement and at the same time vividly manipulates the mouth of a puppet, the movement will draw our attention visually. o We will perceive the puppet to be doing the talking. We have just experienced ventriloquists. Notice, that he did not "throw" his voice as many people believe. The key to good phonemic development is for the parents to spend much time talking to and around their baby. • Ventriloquism is not "throwing" the voice. It is, not moving the lips or the jaw. Even the consonants that require the front-most constriction can be accomplished by the tongue with some practice and will sound just fine. • These are just a few of the distinctive features (building blocks of phonemes) that the baby is equipped to hear at birth. • It remains for the parents to provide the materials (speech sounds) for the child to maintain and strengthen these listening skills. The child who sits alone for long hours in a crib will be at a disadvantage relative to the child who has doting parents hovering about and talking to and chatting about their child. • And if one of the parents is speaking another language, better yet for the baby's developing phonemic structure. Now we are ready to look at the Receptive Transducer for the Auditory Modality- the Ear and see how is interfaces with sound to make speech and language possible, or how it fails to interface and how this impacts on speech and language.