SOUND

SOUND Vibrations that travel through air or another

medium and can be heard when they reach a person’s or animal’s ear is defined

as sound .

USES OF MULTIPLE REFLECTION

OF SOUND….

Megaphones and musical instruments Megaphones or loudhailers, horns, musical instruments are all designed to send sound in a particular direction without spreading it in all directions. In these instruments, a tube followed by a conical opening reflects sounds successively to guide most of the sound waves from the source in the forward direction.

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In stethoscope the sound of a patient's heartbeat is guided by along the tube of the stethoscope to the doctor's ears by multiple reflections of sound.

Curved ceilings of concert halls, conference halls and cinema halls are made curved so that sound after reflection reaches all the corners of the halls.

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RANGE OF HEARING

RANGE OF HEARING INLIVING THINGS

HEARING RANGEHearing Range usually describes the range of frequencies that can be heard by an animal or human, though it can also refer to the range of levels. In humans the audible range of frequencies is usually said to be 20 Hz (cycles per second) to 20 kHz (20,000 Hz), although there is considerable variation between individuals, especially at the high frequency end, where a gradual decline with age is considered normal.

Tunnel echo sound effect - YouTube.3GP

How Megaphones Work - YouTube.3GP

HEARING RANGE IN HUMANSIn a human, sound waves funnel into the ear via the

external ear canal and hit the eardrum (tympanic membrane). Consequently the

compression and rarefaction of the wave set this thin membrane in motion, causing the middle ear bones

(the ossicles; malleus, incus and stapes) to move. The number of sound pressure level vibrations (sonic

waves) per second denotes the frequency. Infrasonic (below hearing), sonic (aural), and ultrasonic (above hearing) frequencies are measured in Hertz (Hz); one Hertz is one cycle wave (or singular pressure wave in

audionics) per second.

Humans have developed culture and technology such as music, telephone and radio . that allows them to generate, record , transmit, and broadcast sound. The scientific study of human sound perception is known as Psychoacoustics.

Psychoacoustics.

INFRASOUNDIf we could hear infra sound we could hear vibrations of pendulum just like how we year flattering of the wings of the bee.

Infra sound producing animals

Ultrasound

Earthquakes produce low frequency infrasound before the main shock waves

begin which alerts the animals

HEARING RANGE IN DOGSThe hearing ability of a dog is dependent on its breed

and age. However, the range of hearing is approximately 40 Hz to 60 kHz, which is much greater

than that of humans. As with humans, some dog breeds become more deaf with age, such as

the German Shepherd and Miniature Poodle. When dogs hear a sound, they will move their ears towards it in order to maximise reception. In order to achieve

this, the ears of a dog are controlled by at least 18 muscles. This allows the ears to tilt and rotate. Ear

shape also allows for the sound to be more accurately heard.

DOG’S EAR

HEARING RANGE IN BATSBats require very sensitive hearing to compensate for

their lack of visual stimuli, particularly in a hunting situation, and for navigation. Their hearing range is

between 20 Hz and 150 kHz. They locate their prey by means of echolocation. A bat will produce a very loud,

short sound and assess the echo when it bounces back. The type of insect and how big it is can be

determined by the quality of the echo and time it takes for the echo to rebound; there are two

types; constant frequency (CF), and frequency modulated (FM) calls that descend in pitch.

HEARING RANGE IN BATS

HEARING AID

A hearing aid is an electroacoustic device which typically fits in or behind the wearer's ear, and is designed to amplify

and modulate sound for the wearer. Earlier devices, known as ear trumpets or ear horns, were passive funnel-

like amplification cones designed to gather sound energy and direct it into the ear canal. Similar devices include the bone

anchored hearing aid, and cochlear implant.

WHAT IS A HEARING AID??

HEARING

AID

THANK

YOU !!

QUESTIONWhy are the ceilings of concert halls curved?Ceilings of concert halls are curved so that sound after reflection (from the walls) spreads uniformly in all directions.

20 Hz to 20,000 Hz

What is the audible range of the average human ear?

What is the range of frequencies associated with(a) Infrasound?(b) Ultrasound?

(a) Infrasound has frequencies less than 20 Hz.(b) Ultrasound has frequencies more than 20,000 Hz.What is a hearing aid? What is it used for?Hearing aid is an electronic battery operated device for people with hearing loss.

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