How do we Hear & Speak?
How do we Hear?
The sound reaching our ears first makes the eardrum vibrate. These vibrations are transmitted through the 3 small bones in the middle ear (hammer, anvil and stirrup) to the cochlea. This results in a movement within the cochlear fluids. Sensitive hair cells in the cochlea register this movement and start a neural activity, which is transmitted through the auditory nerve to the brain. Thus we hear.
How do we Speak?
Speech is an overlaid function. The sctructures meant for sucking, biting, chewing and swallowing are used for the production of speech cords. The vocal cords in the throat meant to protect the lungs from the foreign bodies are used for production of voice. The exhaled air from the lungs is used to vibrate the vocal cords to produce voice. The voice is produced just like a balloon producing sounds when its mouth is stretched. In this way the structure meant for breathing and eating is used for production of voice and speech. However the brain is the master control. The speech is a co-ordinated activity of respiration, phonation and articulation.
Speech refers to the sounds that come out of our mouth and take shape in the form of words. Many things must happen in order for us to speak, like:
- The brain must create an idea if it wants to communicate to someone else.
- The brain must then send that idea to the mouth.
- The brain must tell the mouth which words to say and which sounds make up those words.
- Intonation patterns and accented syllables must be incorporated.
- The brain must also send the proper signals to the muscles that produce speech: those that control the tongue and lips and the jaw.
- These muscles must have the strength and coordination to carry out brain’s commands.
- The lungs must have sufficient air and the muscles in the chest must be strong enough to force the vocal cords to vibrate. The air must be going out, not in, for functional speech to occur.
- The vocal cords must be in good working condition for speech to sound clear and be loud enough to be heard.
- The words produced must be monitored by our hearing sense. This helps us review what is said and hear new words and to imitate in other situations. If words are not heard clearly, speech will be mumbly when reproduced.
- Another person must be willing to communicate with us and listen to what we say.
For most children, these processes happen naturally, if proper stimulation occurs without conscious thought.
For some children, this sequence breaks down. Once the source of the breakdown is identified, these steps can be facilitated in a direct and conscious manner.