Topic: Auditory organ, or how the auditory sensations are created

Author: Elżbieta Szedzianis

Target group

7th‑grade students of an eight‑year elementary school.

Core curriculum

III Human body.

10. Sensory organs. Student:

3) recognises the elements of the ear (on a model, on a drawing, according to their description, etc.) and describes their functions.

5) presents the role of the sense of balance, taste, smell and touch; identifies where the receptors of these senses are, plans and conducts an experiment that checks the closeness of where the receptors are located in the skin on various parts of the body.

Lesson objective

The students describe how the auditory sense works and what its meaning is.

Key Success Criteria

• you will explain how ear is built and explain, why you need this type of knowledge;

• you will present the relationship between how the ear is built and its functions;

• you will describe how auditory sensation is created.

Key Competences

• communicating in the mother tongue;

• communicating in a foreign language;

• Mathematical competence and basic competences in science and technology; 

• digital competence;

• learning to learn;

• social and civic competences.

Methods/Forms of work

work with text, experiment.

Individual work.

Teaching measures

• abstract;

• interactive or traditional whiteboard;

• tablets/computers;

• metal forks;

• bowls with water.

Lesson plan overview (Process)

Introduction

The teacher tells the topic of the lessons, defines the purpose of the course and gives students the criteria for success.

Realization

1. The teacher asks the students to familiarize themselves with the fragment titled “Organ of hearing” and analyze the interactive illustration that presents how the ear is built.

2. The students talk about the build of the ear and present the relationship between how the ear is built and its functions.

3. The students prepare a table that compares specific elements of the ear and their functions.

4. Volunteers or students chosen by the teacher read out selected lines of the table. The rest of the students assess how correctly the task was completed.

5. The students complete Task no. 1.

6. The teacher asks the parents how sound is transferred. The students give their propositions and then, they carry out the experiment. They hit the metal fork on the table and quickly they put it into the bowl with water. They observe the surface of the water. They describe the experiment
   and draw conclusions from it with the help of the teacher.

7. The students read the fragment titled “How auditory sensations are created” and comment on it.

8. The students solve the problem: “Why do we need 2 ears?”.

Summary

The teacher asks the students to explain, how they can use the knowledge on how the ear is built.

Homework

The students complete the interactive exercises no. 1.

The following terms and recordings will be used during this lesson

Terms

Texts and recordings

Organ of hearing, how auditory sensations are created

Ears have two functions: they receive sounds and they inform about the location and movements of the head. Thanks to them we can detect and localize sounds, differentiate their pitch and intensity and register the placement of the body.

Ear consists of three parts: outer ear, middle ear and inner ear. The outer ear is composed of auricle and outer auditory canal. Auricle is a fold of skin stretched on the scaffolding of cartilage. Its shape and folds on the surface are the adaptation to catch sound waves, enhance them and transfer them to the outer auditory canal – a canal closed with tympanic membrane. The inside of the canal consists of hairs and glands that produce fatty secretion – ear wax. Hairs keep away dirt, while ear wax keeps away microbes and dust.

Middle ear is composed of tympanic cavity filled with air in which there are 3 auditory ossicles – smallest bones of our body: malleus, incus and stapes. One end of the malleus is attached to the tympanic membrane and its other end is connected with the incus, while the incus is connected with the stapes. Auditory ossicles are connected with each other by joints.

Tympanic cavity is connected with the throat via a canal called auditory tube (Eustachian tube), which is responsible for evening out the pressure between the middle ear and the environment. The difference in pressure appears for example when a plane takes off and lands, during mountain climbing, while listening to music using earphones and during explosion. It may cause pressure in the ear, pain and problems with hearing. Swallowing saliva means that the outlet of the auditory tube, which is normally closed, opens. Air is exchanged between the tympanic cavity and throat, the pressure in the middle ear evens out with the pressure of the environment and the unpleasant feeling in the ear disappears.

Inner ear has a complicated shape. It consists of a vestibule, colchea and 3 semicircular canals. These are spaces and canals in the bones of a cranium, separated by the membrane. They are filled with liquid (endolymph). Inside the colchea canal there is the actual organ of hearing in form of sensory hair cells. Other parts of the inner ear are the sense of balance.

The stimulus which works on the organ of hearing is a sound wave. Outer ear directs it onto the tympanic membrane. Under the influence of the energy of the acoustic wave, the tympanic membrane starts vibrating. These vibrations are transferred to malleus that is attached to the tympanic membrane. Thanks to the movable joint connections between the auditory ossicles, the vibrations move from the malleus onto the incus and then onto the stapes, which is connected with the inner ear. Vibrations of the stapes cause the liquid in the cochlear canal to vibrate. The sensory hair cells that line the inside of the cochlear canal become irritated which causes electrical impulses. Via auditory nerve they reach the auditory centre in the cerebral cortex where they are read and interpreted.

The assessment of the pitch of the sounds depends on the speed of their vibrations (frequency expressed in hertz, Hz). Sounds with high frequency are interpreted as high, whereas those of low – as low. Sensory epithelium is responsible for differentiating the pitch of the sounds. Different parts of the membrane, depending on their location in the cochlea, receive vibrations of different frequency. The brain differentiates information coming from different groups of cells and assesses the pitch of the sounds.

• Ear is the organ of hearing and balance.

• The actual organ of balance are the receptor cells found inside the cochlear canal.

• Receptor cells of the organ of hearing receive information in form of vibrations of the fluid that fills in the inside of the cochlear canal, whereas the cells of the organ of balance – the movement of the fluid in semicircular canals.

• Auditory sensations are created in the auditory centre in the cerebral cortex.

• 3 semicircular canals that are the part of inner ear are responsible for receiving the stimuli connected with head movement or change in body position.

• Human ear reacts to sounds with the frequency of 16 Hz‑20 thousand Hz and the volume up to 130 dB.