Have you ever wondered what precisely is happening with your child’s speech when he or she is producing a sound incorrectly? Why, when your child looks out the window in the morning, she excitedly tells you that there is a “wabbit” hopping on the lawn? Maybe your child tells you he wants to “toe to the park,” but you know all he really wants to do is “go to the park.” While each child’s speech system remains complex and unique in function and anatomical structure, each speech error can be traced back to a breakdown in one or more areas of the body’s neuromotor speech system. Netsell’s Model for Systems of Speech helps to aptly identify the type and origins of a speech error by thoroughly outlining the systems of speech involved (Netsell, 1991). The systems of speech are outlined as follows…
Respiration: The Powerhouse of the Speech System
While your respiratory system’s primary goal is to keep the body supplied with oxygen, it is also vital in producing out voice! Air itself is the medium which carries sound in speech, specifically on an exhalation (when breathing out); without respiration, there would be no sound to transmit. Think back to a time when were sprinting as quickly as possible! As you came to a halt, gasping for air, and attempted to speak, you found that your voice was almost entirely gone. This is because respiration is primarily concerned with keeping the body alive. Producing speech is secondary to the biological necessity that is breathing; therefore, without effective breathing, there is no speech.
Phonation: Sound and Protection
Much like the respiratory system, our phonatory system has multiple uses as well. Our phonatory system is made up of the trachea, the larynx, and the pharynx; however, we will be focusing specifically on the larynx in terms of phonation, since the larynx contains the vocal cords. While air is the avenue in which sound travels, vocal folds vibrate to produce the acoustic vibrations that create the sound itself. Damage to the vocal folds can result in changes in pitch, volume, and overall vocal control. Think of air as a freeway in which cars travel, sound as the car, and your vocal folds as the machines that make the car. If the machines are not working properly, they will not create an effective car. In the same way, if the vocal cords are not working effectively, they will likely not create the desired sounds.
Articulation- Sound Shapers
According to the American Speech and Hearing Association, roughly 5% of children have some discernable speech disorder. That is approximately 3.75 million children nationally (ASHA)! These speech disorders are most often caused by errors occurring in the articulatory speech system. Articulation refers to the formation of specific sounds for speech using articulatory structures and musculature. Our articulators include the lips, tongue, teeth, jaw, and palate (the roof of your mouth); however, the tongue is the MOST important articulator for speech. The tongue must perform incredibly quick and precise movements in order to coordinate most of the sounds needed for speech. For example, if the tongue slips slightly towards the front of your mouth when you are saying the word “shy,” it could easily change to the word “sigh,” which would create an entirely different message to your audience and subsequently cause a breakdown in communication.
Resonance: Tone Shapers
Resonance refers to the way that sound reverberates off the cavities and structures in your nose, mouth, and throat. The back half of the roof of your mouth consists of a structure called the soft palate or velum, which both separates from and articulates with the back of your throat to help control if sound resonates in your nose or your mouth. Have you ever watched the TV show Friends? Remember Janice? Janice’s voice is a perfect example of someone whose velum is not articulating with the back of the throat enough, allowing air to escape and resonate profusely in the nose. Now think of when you have had a cold or sinus infection. You might tell your spouse, “Please get be a tissue.” Why did you say “be”? Because the “m” in “me” is a nasal sound and is produced when your velum is open, allowing air to flow through nasal cavity and resonate there. When you are congested, the added gunk is not allowing air to reverberate within the nasal cavity, pushing the air into the oral cavity and creating a wholly different sound.
Prosody: An additional system that relies on the coordination between the other four systems!
Prosody is sometimes indicated in the Netsell Model because, while prosody is extremely important for communication, it cannot not exist in a sphere of its own. It is rather a combination of the other systems. Prosody refers to the patterns within your speech, and how those patterns can communicate additional information regarding your message. Prosodic features include pitch, tone, rhythm, stress, and accent. Anyone with a parent or guardian knows that a person’s tone of voice can greatly change the way that a message is communicated. Also, consider the word “record.” It is spelled the same no matter where the stress occurs within the word; however, if I put the stress on the first half of the word, I could say “I want to record the Olympics.” However, if I put the stress on the second half of the word, I could convey that, “I hold the world record in an Olympic event.” Stress on a syllable can change a simple word from a noun to a verb.
As you can see outlined above, our speech system is incredibly complicated and synergistic! If one small muscle or structure is not working in a precise manner, a breakdown in communication can occur. Effective communication is one of the most vital skills a person can possess. It helps children build relationships, express feelings, inform and influence others, and interpret the world around them. Every child has the right to be heard and understood. Our primary goal as Speech-Language Pathologists is to help children obtain this right, which often starts with speech.
References American Speech-Language-Hearing Association. (n.d.). Developmental Norms for Speech and Language. https://www.asha.org/slp/schools/prof-consult/norms/ Duffy, J. R. (1995). Motor Speech Disorders: Substrates, Differential Diagnosis, and Management. https://ci.nii.ac.jp/ncid/BA75420329 Netsell, R. (1991). A Neurobiologic View of Speech Production and the Dysarthrias. http://ci.nii.ac.jp/ncid/BA76235898