HearingThe vibrational energy of vibrating objects,

such as guitar strings, transfer the surrounding medium-air-as the vibrating objects push the molecules of the medium back and forth.

In space, there is no air, so the sound wave would have no medium to push. Any explosion would be eerily without sound.

Hearing

Frequency and AmplitudeThere are two physical characteristics of

sound: frequency and amplitude.

Frequency: The number of cycles completed by a wave in a given amount of time.

Amplitude: The physical strength of a wave.

Pitch: This is how high or low a sound seems. A bird makes

a high pitch. A lion makes a

low pitch

Sound.Sounds also

are different

in how loud

and how soft

they are.

Quality.

Pitch and loudness are two ways that sounds are different.

Another way is in quality.

Some sounds are pleasant and some are a noise.

Getting Started

Draw two pictures of sound waves showing the following Two waves with a different pitch but the same

loudness Two waves with different loudness but the same pitch

If a tree falls in the forest…The question “If a tree falls in the forest and

there is no one around to hear it, does it still make a sound?” can now be answered.

No, it would make no noise.

Sound is a purely psychological sensation that requires an ear (and the rest of the auditory system) to produce it.

Parts of the ear

Eardrum: Structure at the end of the ear canal that vibrates to transmit messages to the inner ear

Parts of the ear

Cochlea: Inner ear that contains fluids and neurons that change vibrations to the sounds we hear

Parts of the ear

Auditory Nerve: carries the cochlea's message to the brain

DeafnessThere are generally two types of deafness.

Conduction deafness is an inability to hear, resulting from damage to the structures of the middle or inner ear.

Nerve deafness (Sensorineural Deafness) is an inability to hear, linked to a deficit in the body’s ability to transmit impulses from the cochlea to the brain.

How the Other Senses are Like Vision and Hearing

Each gives us information about a different aspect of our internal or external environment. Yet each operates on similar principles.

Each transduces physical stimuli into neural activity and each is more sensitive to change than to constant stimulation.

Our SensesYou will notice that all of our sense organs

are very much alike. They all transform physical stimulation (such as light waves or sound waves) into the neural impulses what give us sensations (such as light and dark).