Introduction to Speech and Hearing
Dr. Pamela Broadston
Thursday, October 21, 2004
Transcriber: Pamela J. Barnes
Professor: Hello everyone. Today we start our unit on anatomy and physiology of speech. We have completed the unit on the anatomy and physiology of hearing. We talked a little bit about how the two systems are interrelated. I just wanted to kind of review that a little bit before we moved on.
Speech is a very, very, complex process. It involves multiple systems within the body to create speech. Also speech production and speech reception go hand in hand. Remember when we talked about the tree falling in the forest. If there wasn't anybody there to hear it is it really sound? It kind of goes the same way with speech. If there isn't anybody there to receive speech what is the point.
You need both a speaker and a listener. So speech reception and speech production go hand in hand. The speaker is the one who formulates the message in the brain, conveys it through impulses via the nervous system to the appropriate muscles in the body.
The muscles move the appropriate structures that make the message audible. It is a very complex system. This is so the speaker can produce the thought that they had and then produce the speech.
Then the listener through their auditory system interprets the message once it reaches the appropriate location in the brain. Remember we talked about the sound wave comes in and has to go through the outer ear, the middle ear and changes to mechanical energy. Then it goes to the inner ear and changes to electrical energy and on to the brain to the auditory cortex. So, speech reception is also a very complex process.
What we have to remember is that both the speaker and the listener have identical parts within the body structure that are used for speech communication. Speech is just speech if there is no communication. The main purpose is for there to be communication or interaction between two or more people. [Clears throat]
The neat thing about the human system, and this makes it more complex, is that if there is somewhat of a breakdown in either the speaker's system or the listener's system often the message can still be conveyed. Sometimes if there is damage to a certain portion of the brain, other portions of the brain can take over that function. Speech can be produced and received. If there is a problem with the ear, ok, speech may not be received auditorily but speech can be received visually through speech reading. We will talk a little bit more about that.
So the brain and the peripheral auditory system are able to compensate in many ways through this complex structure in order to produce and receive speech. [Pause]
We have already talked about the body parts involved in speech reception. Now we will move on to the body system involved in speech production. There are three main systems in the body that are crucial for speech production. It starts with the respiratory system. A lot of people think respiration is breathing. "That is keeping my body alive. It doesn't have anything to do with speech." It does. You have to the air. You have to have the output from the lungs to produce the sounds which are turned into speech sounds through the other systems: the laryngeal system and the supralaryngeal system.
Then the respiratory system is what provides the respiration or the air exponent of the air to start the production of sound. The laryngeal system system provides for phonation of the sound. The supralaryngeal system is what provides for articulation of a sound. Let me show you a little diagram of what I am talking about.
The respiration system, we have the two primary parts are the lungs and the trachea. Also right below the lungs is the diaphragm. We have all of the skeletal structures and muscles involved in protecting and controlling the lungs, trachea and the inhalation and exhalation of air. We will be talking about all of those structures in today's lecture.
Then in the next lecture we will talk about phonation. This occurs at the larynx or the laryngeal system. Then the last system we will talk about in another lecture is the supralaryngeal system or above the laryngeal system. That is where articulation occurs. This is through the pharynx and the oral cavity and the nasal cavity as well as all of the pieces of musculature, apparatus, and structures that are involved in the articulation mechanism is what actually then produces the speech.
So today we are just going to be talking about the respiration system. As I said, the respiration system is the energy source for speech. You have to have that output of air in order to have speech production. [Clears throat]. Even though one of the primary purposes of respiration [for us] and respiration in other animals is to sustain life through the process of breathing. We also use a type of breathing to then produce speech. Other animals as well use respiration to produce sounds often intentional sounds that can convey meaning, but not through speech.
Speech is either produced on the inhalation of air which is the ingressive or the exhalation which is the egressive air. Most English sounds are produced on the exhalation of sound. Many other languages actually have sounds that are done on the inhalation. It is a little bit difficult for us those of us who are native English speakers. It is a little bit difficult to do. I just want to show you that it is possible to produce sounds on the inhalation. Right now everything I am doing is on the exhalation. Air is coming out of my body, lungs, through the larynx, pharynx, oral cavity and nasal cavity.
I want you to try this with me. I want you to produce the sound ahhhh. The air is coming out. I want you to breathe in and produce the same sound. [Breathes in]. Hahhhhhhh. Ok its taking me a second. Let's try again. [Breathes in]. Haaahhhhhh I can produce the ahhhh sound. It is a little higher in pitch. I can produce that sound through an inhalation. It is very uncomfortable and difficult to do. We don't do that to produce any of the English phonemes. Other languages such as African languages have a sound that is produced on the inhalation.
So the first part of the respiration system is actually housed in what is called the thoraxic cavity. It houses the lung and the heart. The spinal cord is the posterior, or back part, of the thoraxic cavity. The sternum or the breast plate is the interior or front side of the thoraxic cavity. We have to talk about the thoraxic cavity as a whole. Even though the lungs actually produce the air, it actually takes the air in and exhales the air, it is all of the intricacies of the system working together. The structures are working together. This allows for the control of the air flow. So we have to talk about the various parts that are involved.
I am sorry. I went on. That was the ingressive and the egressive. Here we are moving on to the parts of the anatomy that are involved in respiration. First we have to talk about the skeletal framework. [Pause]
We have the skeleton. Basically when we are talking about respiration we are talking about from this area where the diaphragm is supported. The diaphragm is a muscle that separates the thoraxic cavity from the abdominal cavity. We have the rib cage which is very critical in the respiration process. This is where the muscles attach that allow the rib cage to move and the lungs to be able to fill and exhale and contract back in during respiration. The abdominal area is very important. The abdominal muscles actually control exhalation. We will talk about that in a minute. Without the rib cage we would not have a cage that is protecting the lungs and the heart. We would not have an area where muscles can be attached that controls the expansion and the contraction of the rib cage.
We have the spinal cord. The vertrebral column, or spinal cord, is a set of bones through which the spinal cord runs through. This is the back portion of the thoraxic cavity, the thoraxic verterbrae which runs through the back of the thoraxic cavity. Your book goes into more detail. For our purposes it is not that crucial that you understand the fine workings of the spinal cord. Just know that it is part of thoraxic cavity in which the lungs are housed. That is crucial for the production of speech.
Then also we have the clavicle or the collar bone. All things considered it is considered part of the rib cage. It expands and contracts. There are muscles that attach to the clavicle that are important for the inhalation of air. Across the back you have your shoulder blades which are also important because muscles attach there to move the ribs out so the lungs can expand.
The muscles I just talked about ... we have to start with the skeletal framework. We have the spinal column, or the vetrebral column and the rib cage. That is the skeletal framework that we are interested for respiration. Then we have the muscles of respiration. We have inhalation muscles which allow the rib cage to raise up and expand out. Aaaaaaaah. Feel how your rib cage is getting bigger and the ribs are moving to allow your bones to expand to inhale air. I am exaggerating. We don't generally do that when we speak. Singers do that when they sing to get more air into the lung.
The exhalation process is what depresses the lungs back down forcing the air out. The forcing of the air out through the larynx, pharynx, oral cavity and nasal cavity is how speech is produced. Then we have this wonderful little muscle called the diaphragm. This is a curved muscle that separates the thoraxic cavity from the abdominal cavity. It is actually a muscle. It is contracts down when you are filling your lungs with air. It provides more room down into the abdominal area to allow your lungs to expand more fully. [Pause]
Actually ... let me get this down a little bit more. Right here is what I was talking about with the diaphragm. The diaphragm actually contracts down to allow the lungs to expand and provide more air. If you are a singer then you really know about that when you learn to control the diaphragm to use it efficiently when you are singing. You need the extra power and air to sing. Singers really know how to control that muscles much more effectively than those who don't sing. It does take training to use. Its not something we actually use for typical speech production.
Now we are going to talk specifically about those muscles that are involved for inhalation as well as the muscles involved for exhalation. Those are the crucial parts. For the production and control of the air, when we think about respiration the lungs and trachea are the most important. There is not a whole lot I can say about that. The lungs take in and put out air. It is all the other structures that control air flow in and out. That is so crucial to speech production.
So we have a set of muscles that are used for inhalation. The four, well actually five, major muscles are: Pectoralis major Pectoralis minor Intercostals (2 sets of muscles): External intercostals Internal intercostals Diaphragm
Pectoralis major and minor raise the ribs to allow for air flow into the lungs. The intercostals, both internal and external, are attached to the ribs. They hold the ribs together to allow them to expand. They keep them aligned and in the proper place. Let me show you another diagram of that. [Pause]
Ok here you have the pectoralis minor muscles and they contract and the intercostal muscles contract. The diaphragm contracts and flattens down and this allows the lungs to expand. The pectoralis major muscles also contract in this processes. Those are across the back and you can't see them in this picture. That is how all of this musculature works together in combination with the rib cage to expand up and out to allow the lungs to feel with air.
Then during exhalation we talk about the pectoralis major and minor muscles relaxing. The intercostal muscles relax so everything can come back together. The diaphragm relaxes and it releases back up. When the diaphragm contracts it contracts down to make a bigger space. When it relaxes it expands back up and shortens that space between the thoraxic and abdominal cavities.
To inhale we have to have those muscles working properly. When we exhale it is actually the abdominal muscles that squeeze and push the air out. This is when we are talking about speech breathing. We will talk about vegetative and speech breathing in just a mmute. When we are talking about the inhalation and exhalation of air for speech or singing this is where the abdominal muscles come into play. We have the external oblique, the rectus abdominous and the transverse abdominous which contracts and pushes air back out of the lungs.
Let me show you ... hold on a second. Let me back up a step. I have one more picture that I wanted to show you about the intercostals so you could kind of understand exactly how the intercostals are attached to the rib cage. I apologize. These are the actually the individual ribs. These are the muscles that attach between those ribs. So that allows the ribs to expand apart as you are breathing in to allow more room for the lungs. Hold them in place so that when you exhale they can shrink back in. The muscles actually pull the ribs back into alignment.
So here is this familiar picture of how that works between the two ribs - the internal intercostals and the external intercostals. The internals are on the inside of the rib cage. The externals are on the outside of the rib cage. That is how they work to allow those ribs to expand and contract.
Here is just one more picture showing the muscles on the entire rib cage. You have the external intercostals on the outside. You have the internal intercostals on the inside.
So remember the intercostals are the important muscles for inhalation. This makes the space bigger for the lungs to expand when you intake air. We were talking about the muscles for exhalation. Again that is the abdominal muscles. You don't think of the abdominal muscles being involved. You think these contract and they release and that pushes the air out. It really is not. The abdominal muscles are crucial for controlling the air flow so that speech can be produced. Again those muscles are the external oblique, rectus abdominous, transverse abdominous.
This is the abdomen. This is how those muscles run. Some of the muscles run up and down the abdomen. Some of them run across the abdomen. These are external oblique, internal oblique, the transverse abdominous and the rectus abdominous. They run up the center of your stomach.
In the exhalation process these muscles of the abdomen actually pull your rib cage in and down. This forces the air out of your lung.
I want to talk about vegetative breathing and speech breathing. The muscles of those areas that we just talked about that control the rib cage react a little differently depending on the type of breathing you are doing. Vegetative breathing is breathing while you are sitting still, sleeping, or not talking. Instead of actually the abdominal muscles coming into play and contracting to pull that rib cage to force the air down it is actually gravity that does that. You actually actively engage your muscles [breathes in]. To expand your lungs, and rib cage so the rib cage can expand. When you are not talking and just breathing it is actually gravity that pulls those muscles back down into place and pulls the bones of the rib cage into place.
When you are thinking about it think about how you are breathing when you are not talking. Just see if you can tell the difference between how your body reacts. See that when you are talking that there is much more involvement of the abdominal muscles than when you are breathing. Example: when you are laying down to sleep. Try it tonight to see if you can see the difference in how your muscles are responding. With speech breathing the exhalation process is actually the contraction of the abdominal muscles which control the expulsion of the air. This is necessary for phonation to occur in the larynx and articulation to occur for the production of sounds.
There is new research that shows that the abdominal muscles actually are engage throughout the entire time of the speech process. This is beyond the intial stage of the exhalation process. It used to be thought that the abdominal muscles were involved at the initial exhale. Then speech was controlled and all of these other muscles control air flow. There is new research that shows that your abdominal muscles stay engaged throughout the entire speech process. So my abdominal muscles should be really working right now [laughing] since I have been talking so much. Darn I don't think it really works that way. We do have the research that shows that it is not just the initial contraction of muscles to provide the burst of air. They stay engaged somewhat to control the air flow through the trachea and out into the pharynx.
So next week we will be talking about the laryngeal system which is where phonation occurs. We will be talking about the supralaryngeal system (or above the laryngeal system system). This takes into account all of the articulators: your tongue, teeth, lips, nasal cavity, nose. When you make Mmmm sounds and NNN sounds those go up through your nose. So all of those cavities and those structures are very, very important for the production of speech. We will go into more detail of the other systems next week. Have a great week and we will see you next time. [end of class]