Presented by trivenee & Manisha

Student needsHow can create new slide? What is mean by sound?Which is characteristics of sound waves?What is echo sound?How to prevention to avoid reverberation sound?How to collect information of prevention of

sound pollution?What is noise pollution?How to collect information of prevention of noise

pollution?

AIMS OF PROJECTStudents will recognize that the human body

is the made of system with structures and functions are related and serve different function in growth & survival.

student know the understand interrelationship among science ,technology & human activity & how they can affect the world.

Sound

Sound means basically the mechanical vibrations.

These vibrations require a material medium to travel through.

eg : Solid, liquid, gas, plasma Meaning Sound cannot travel through

Vacuum. (Why ?)

Sound travels in form of wavesLongitudinal waves

Characteristics of waves

AmplitudeWavelengthFrequency

Time periodVelocity of wave

Play

Wavelength •The distance between any two adjacent wave crests1 (wave crests that are next to each other) or any two adjacent wave troughs2 in a wave.

1. Crest: The highest point reached by a wave.2. Trough: The lowest point reached by a wave.

Amplitude (A)•The maximum displacement (difference between an original position and a later position) of the material that is vibrating. Amplitude can be thought of visually as the highest and lowest points of a wave.

Frequency (f/n)•The number of wave crests (or wave troughs) that pass a given point per unit of time (usually per second).• Frequency (f) = 1 / Time Period (T)• SI unit of ‘f’ is Hertz (Hz).• Hz = 1 / sec

Time period (T)• It is the time taken by a wave to complete a certain number of fixed oscillations. Usually of 1 wavelength.

Spring 2006

UCSD: Physics 8; 2006

13

Sound is a longitudinal wave, meaning that the motion of particles is along the direction of propagation

Transverse waves—water waves, light—have things moving perpendicular to the direction of propagation

How sound is produced

Sound travels due to vibrations (disturbance) produced in the medium.

Video 1Video 2Video 3Video 4

EchoReflection of sound is called Echo.We can hear two consecutive sounds only if

there is a time gap of 1/10th of a second (0.1s).

Note that this value is only for sound in air and will be different for different mediums.

Let us calculate the minimum distance to hear a Echo…..

ReverberationBasically it is unwanted Echo.Reverberation in a hall can be avoided by use

of : i. Panels made of porous & soft materials.ii.Using floor carpetsiii.Using curtains, sofa sets etc.

Human Ear• Human ear senses sound by the vibration of ear drums. eg: Video 1 , Video 2, Video 3• The human can hear all the frequencies between 20 – 20,000 Hz.• Frequencies < 20 Hz are called Infrasonic. eg : Whales• Frequencies > 20,000 Hz are called Ultrasonic. eg : Bats

Spring 2006

UCSD: Physics 8; 2006

18

Sound is a longitudinal wave, meaning that the motion of particles is along the direction of propagation

Transverse waves—water waves, light—have things moving perpendicular to the direction of propagation

Noise pollution

Noise pollution is excessive, displeasing human, animal or machine-created environmental noise .that disrupts the activity or balance of human or animal life. The word noise comes from the Latin word nauseas meaning seasickness.

The source of most outdoor noise worldwide is mainly construction and transportation systems, including motor vehicle noise, aircraft noise and rail noise.[1][2] Poor urban planning may give rise to noise pollution, since side-by-side industrial and residential buildings can result in noise pollution in the residential area.

1 Health effects 1.1 Human health 1.2 Wildlife health

2 Impact in the United Kingdom 3 Mitigation and control of noise 4 Legal status 5 See also 6 References

7 External link

Health effectsHuman healthNoise health effects are both health and behavioral in nature. The unwanted sound is called noise. This unwanted sound can damage physiological and psychological health. Noise pollution can cause annoyance and aggression, hypertension, high stress levels, tinnitus, hearing loss, sleep disturbances, and other harmful effects.[3][4][5][6] Furthermore, stress and hypertension are the leading causes to health problems, whereas tinnitus can lead to forgetfulness, severe depression and at times panic attacks.[4][7]

Chronic exposure to noise may cause noise-induced hearing loss.

Wildlife healthNoise can have a detrimental effect on animals, increasing the risk of death by changing the delicate balance in predator or prey detection and avoidance, and interfering the use of the sounds in communication especially in relation to reproduction and in navigation. Acoustic overexposure can lead to temporary or permanent loss of hearing.

Mitigation and control of noiseMain article: Noise mitigat

The sound tube in Melbourne, Australia, designed to reduce roadway noise without distracting from the area's aesthetics.

Technology to mitigate or remove noise can be applied as follows:There are a variety of strategies for mitigating roadway noise including: use of noise barriers, limitation of vehicle speeds, alteration of roadway surface texture, limitation of heavy vehicles, use of traffic controls that smooth vehicle flow to reduce braking and acceleration, and tire design. An important factor in applying these strategies is a computer model for roadway noise, that is capable of addressing local topography, meteorology, traffic operations and hypothetical mitigation. Costs of building-in mitigation can be modest, provided these solutions are sought in the planning stage of a roadway project.

Types of noise controlThere are four basic principles of noise control:Sound insulation : prevent the transmission of noise by the introduction of a mass barrier. Common materials have high-density properties such as brick, thick glass, concrete, metal etc.Sound absorption: a porous material which acts as a ‘noise sponge’ by converting the sound energy into heat within the material. Common sound absorption materials include decoupled lead-based tiles, open cell foams and fiberglassVibration damping: applicable for large vibrating surfaces. The damping mechanism works by extracting the vibration energy from the thin sheet and dissipating it as heat. Vibration isolation.

Noise control is an active

or passive means of reducing sound emissions, often incentivised by personal comfort, environmental considerations or legal compliance.