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The Ear, Sound, Hearing, and the answer to everything? Essential Question • How do we hear? • What does the auditory system (ear + brain) look like and how does it work? Objectives • Name the parts of the ear? • Describe how sound is heard? • Explain how energy, sound waves, and hearing are related. How is energy, sound waves, and hearing related. • A mechanical wave is a repeating disturbance or vibration that transfers or moves energy from place to place. • Waves are created when a source of energy (force) causes a vibration. • A vibration is a repeated back-and-forth or up-anddown motion. • Waves carry energy through a medium without transporting matter. • A medium is a material through which waves can travel. It can be a solid, liquid, or gas. • When waves travel through a medium, the particles of the medium are not carried along with the wave. How is energy, sound waves, and hearing related. • The disturbances (a Mechanical energy source) that travel as sound are called vibrations. • Remember, sound waves require a medium to travel and are LONGITUDINAL (compression) WAVES • A medium is a gas, liquid, or solid and energy goes through the medium without carrying the medium • Think slinky How is energy, sound waves, and hearing related. Sound is collected by the visible part of the ear and directed through the outer ear canal. Mechanical Energy The sound makes the eardrum vibrate, which in turn causes a series of three tiny bones (the hammer, the anvil, and the stirrup) in the middle ear to vibrate. Mechanical Energy The vibration is transferred to the snail-shaped cochlea in the inner ear. Hydraulic Energy The cochlea is lined with sensitive hairs which trigger the generation of nerve signals that are sent to the brain. Electrical and Chemical energy The perception of sound is found in this area The Ear Activity Draw and label, do not copy and paste. Anvil Hammer Stirrup Estuation tube • Hearing… – The hearing system is based solely on physical movement. – Sound occurs when it vibrates in matter. (Solid, Liquid, Gas). Copyright © 2010 Ryan P. Murphy • To hear, you must… – Direct the sound waves into the Ear Canal using the Pinna aka the Outer ear: Pinna Copyright © 2010 Ryan P. Murphy Function of Outer Ear • • • • Collect sound Focuses sound Reverberator Protection Pinna • The visible portion that is commonly referred to as "the ear" • Helps localize sound sources • Directs sound into the ear • Each individual's pinna changes the acoustic wave traveling into the auditory canal and everyone hears differently Middle Ear 1999, Electronic Deaf Education Network Function of Middle Ear • Conduction – Conducts sound from the outer ear to the inner ear • Protection – Creates a barrier that protects the middle and inner areas from foreign objects • Transducer (A transducer is a device that converts a signal in one form of energy to another form of energy.) – Converts acoustic energy to mechanical energy – Converts mechanical energy to hydraulic energy • Amplifier – only about 1/1000 of the acoustic energy in air would be transmitted to the inner-ear fluids (about 30 dB hearing loss) if the middle ear does not work correctly • To hear, you must… – Direct the sound waves into the hearing part of the ear to the ear drum. – The eardrum vibrates from the compression and rarefaction of the air. Pinna The Eardrum • The eardrum separates the outer ear from the middle ear • Creates a barrier that protects the middle and inner areas from foreign objects • Cone-shaped in appearance – about 17.5 mm in diameter • The eardrum vibrates in response to sound pressure waves. • The membrane movement is incredibly small – as little as one-billionth of a centimeter Eustachian Tube provides a way to equalize the pressure between in middle ear and outer ear From www.unc.edu/courses/psyc21/3-26-99/sld010.htm Ossicles: Bones of the middle ear M. Malleus (hammer) I. Incus (anvil) S. Stapes (stirrup) smallest bone of the body • To hear, you must… – Direct the sound waves into the hearing part of the ear. – Mover with the air pressure vibrations in the ear drum and ossicle bones. – Change these vibrations into an electrical signal in the Cochlear organ and out through the auditory nerve that your brain can understand. Pinna The inner ear also houses our organs of balance • Organs of balance are part of the inner ear • They include – Semicircular canals • These organs sense body position and movement Copyright © 2009 Pearson Education, Inc. Answer in your ISN: the next slide shows the answers. Word Bank: Ear Drum, Eustachian Canal, Anvil, Cochlea, Hammer • A tiny bone that passes vibrations from the hammer to the stirrup. • A spiral-shaped, fluid-filled inner ear structure; it is lined with cilia (tiny hairs) that move when vibrated and cause a nerve impulse to form. • (Also called the tympanic membrane) a thin membrane that vibrates when sound waves reach it. • A tube that connects the middle ear to the back of the nose; it equalizes the pressure between the middle ear and the air outside. • A tiny bone that passes vibrations from the eardrum to the anvil. Copyright © 2010 Ryan P. Murphy • Use Deductive Reasoning. (Frontal Cortex) • Use your deductive reasoning skills: Word Bank: • Ear Drum, Eustachian Canal, Anvil, Cochlea, Hammer • Anvil - A tiny bone that passes vibrations from the hammer to the stirrup. Cochlea - A spiral-shaped, fluid-filled inner ear structure; it is lined with cilia (tiny hairs) that move when vibrated and cause a nerve impulse to form. Eardrum -(Also called the tympanic membrane) a thin membrane that vibrates when sound waves reach it. Eustachian Canal - A tube that connects the middle ear to the back of the nose; it equalizes the pressure between the middle ear and the air outside. – When your ears pop as you change altitude (going up a mountain or in an airplane), you are equalizing the air pressure in your middle ear. • Hammer - A tiny bone that passes vibrations from the eardrum to the anvil. Copyright © 2010 Ryan P. Murphy • Answer in you ISN: The next slide has the answers Word Bank: Pinna, Nerves, Stirrup, Ear Canal, Semicircular Canals. • These carry electro-chemical signals from the inner ear (the cochlea) to the brain. • The tube through which sound travels to the eardrum. • The visible part of the outer ear. It collects sound and directs it into the outer ear canal • Three loops of fluid-filled tubes that are attached to the cochlea in the inner ear. They help us maintain our sense of balance. • A tiny, U-shaped bone that passes vibrations from the stirrup to the cochlea. This is the smallest bone in the human body (it is 0.25 to 0.33 cm long). Copyright © 2010 Ryan P. Murphy • Use Deductive Reasoning. (Frontal Cortex) • Word Bank: Pinna, Nerves, Stirrup, Ear Canal, Semicircular Canals. • Nerves - These carry electro-chemical signals from the inner ear (the cochlea) to the brain. Ear canal - The tube through which sound travels to the eardrum. Pinna - The visible part of the outer ear. It collects sound and directs it into the outer ear canal Semicircular Canals - Three loops of fluid-filled tubes that are attached to the cochlea in the inner ear. They help us maintain our sense of balance. Stirrup - A tiny, U-shaped bone that passes vibrations from the stirrup to the cochlea. This is the smallest bone in the human body (it is 0.25 to 0.33 cm long). Copyright © 2010 Ryan P. Murphy • Loudness is measured in decibels (dB) – – This is the force of sound waves against the ear. The louder the sound, the more decibels. – – – – – – – – – Ticking Watch 20 Whisper 30 Normal Speech 50 Car 60 Alarm Clock 80 Lawn Mower 95 Chain Saw 110 Jackhammer 120 Jet Engine 130 Copyright © 2010 Ryan P. Murphy • Sounds that are too loud or that last a long time can cause Noise-induced hearing loss (NIHL). Our sensitive hair cells convert sound energy into electrical signals that travel to the brain and can become damaged. Once damaged, our hair cells cannot grow back. Copyright © 2010 Ryan P. Murphy