sound & hearing

7/31/2019 Sound & Hearing

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Sound & Hearing

Production of Sound

1.Sound is a form of energy(bunyi ialah satu bentuk tenaga)2.Sound is produced from vibrations(bunyi dihasilkan daripada getaran)


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3.Perubahan tenaga yang berlaku

semasa penghasilan bunyi: kinetic energy sound energy

Tenaga kinetik tenaga bunyi


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Transmission of sound

(pemindahan bunyi) The transmission of sound requires a

medium (pemindahan bunyiperlukan

medium) Sound can travel through solid, liquid and

gas (bunyi boleh bergerak melalui pepejal,cecair & gas)


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Sound travels fastest through solid andslowest through gas. This is due to the

compact arrangement of the particles insolid which transmit the vibrationseffectively (bunyi bergerak dengan cepatmelalui pepejal dan bergerak perlahan

melalui gas) Sound cannot travel through the vacuum

(bunyi tidak dapat bergerak melalui

vakuum)


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Reflection and absorption of sound

Sound can be reflected or absorbedwhen it hits a surface

Hard and smooth surfaces are likeconcrete and stone walls can reflect

sound effectively Soft and porous material like cloth and

cotton are weak reflectors of sound but

are good absorbers of sound


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The reflection of sound causes echo tobe formed in caves, tunnels or closed

halls. Echoes are sounds that arereflected from a surface

Practical applications of the reflection

of sound include:a.determining the depth of the sea byships

b.determining the presence of fish (byfishermen) and the presence of enemysship by a submarine (warfare)


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c.Determining distances by bats anddolphins to help in their movements

6. Applications of the absorption ofsound include:

a. Walls of halls and big buildings like

theatres have soft boards and curtainsto absorb sound and thus reduce echo(reflection of sound)

b. cushion and soft padding in carsabsorb noise from the engine


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Hearing defects The most common hearing defect is deafness

Deafness is a hearing defect that is causedby damage to some part of the ear, forinstance:

a. tearing of the eardrumb. damage to the ossicles

c. damage to the auditory nerve

d. damage to the cochleae. damage to the hearing centre of the brain


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In some cases, the hearing defects canbe corrected through surgery or by

using hearing aids. Damaged ossicles can be replaced and

torn eardrums can be patched

Some cases of hearing defects cannotbe cured, e.g damage to the auditorynerve, cochlea or hearing centre of the

brain


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Limitations of the sense

of hearing The hearing of humans has its limits Very low frequency or very high

frequency sounds cannot be heard byhumans


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Hearing Aids The following are a few instruments

that can amplify weak sounds:

a. stethoscope

-amplifies the heartbeat


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b. Microphone &

loudspeaker


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c.Hearing aid Used by people with hearing defects


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Stereophonic hearing Stereophonic hearing is the hearing usingboth ears

Stereophonic hearing enables us to

determine the direction of the soundaccurately

The direction of the sound is difficult todetermine if only one year is used forhearing


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Human ear can hear sound at certain range offrequencies between 20 Hz to 20 000 Hz

Animal Audible frequency range(Hz)

Snake 100-800Frog 50-10 000

Grasshopper

100-15 000

Dog 60-50 000

Cat 50-60 000

bat 1000-130 000


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Monocular long-

sightedness concave lens blind-spot

short-sightednessstereoscopic

optical illusion convex lens

Cylindrical lensastigmatism


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1.Sound is produced by

vibrations.


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2. Sound can travel through

solid, liquid and gas.


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3. A soft surface is a poor

reflector of sound.


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4. When an object vibrates,

only heat is produced.


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5. A hard surface is a good

absorber of sound.


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6. The reflection of sound

produces echo in a tunnel.


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1.Stereophonichearing is the

hearing using


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2.A doctor uses

. To listen to apatients heartbeat


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3. A bat has a

range of frequencyfor hearing compared

to humans.


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4. A ( hearing aid,

microscope)increases our

capability to hearweak sounds.


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5. Hearing with one ear

makes it difficult todetermine the

(strength, direction)of the sound.

sound & hearing

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