Sound - Audible Range And Noise Pollution
Transcript
00:00Hi kids, today we will learn more about sound, so let's get started.
00:12Sound.
00:13Kids, we now know that sound is a vibration that can be heard by human ear, and it can
00:20travel through solids, liquids, and gases.
00:25Now let's learn what is the speed of sound in different mediums.
00:31In dry air, sound travels at 343 meters per second.
00:38In water, 1,482 meters per second.
00:48In steel, 4,512 meters per second.
00:57So denser the medium, faster the speed of sound.
01:01The speed of sound is least in dry air, and it increases from air to water to steel.
01:12Steel is the most densest material here.
01:16Volume of sound.
01:18Volume of sound is measured in decibels.
01:22Just like temperature can be even below zero degrees, same way volume of sound can be below
01:29zero decibels.
01:32Let's learn some.
01:35Typical sound levels in decibels.
01:39An average person can hear sounds with the volume zero decibels, and some persons with
01:46very sharp hearing can even hear sound with the volume about negative 15 decibels.
01:56A very small pin of dropping on the floor may make sound up to 20 decibels.
02:04Whispering may make sound in the range of 30 to 40 decibels.
02:10Normal conversation ranges from 50 to 70 decibels.
02:17Very loud music may range from 80 to 90 decibels.
02:23Industries may make noise up to 110 decibels.
02:29Jet plane takeoffs may make noise up to 120 decibels.
02:36A gunshot may make noise up to 130 decibels.
02:43When the volume of noises we hear reaches 85 decibels or above, it can permanently damage
02:51hair cells in the cochlea of our ear, which is the main hearing organ, and is present
02:58in the inner ear, and a person can then become deaf.
03:03The amount of time we are exposed to loud noise determines the extent of loss that can
03:09happen to our ears.
03:12Listening to personal music system at maximum volume can reach a level of 100 decibels that
03:19can damage our ears permanently.
03:25Loud sound generated by lightning or thunder may range up to 120 decibels that can immediately
03:34harm delicate ears.
03:37You can listen to low volume music for a long time without any harm to your ears.
03:45Noise Now kids, let's see what is noise.
03:51Noise is also a sound, but what's the difference between noise and sound?
03:58Noise is a sound that is unwanted, unpleasant, and disturbs people.
04:05For example, if we are listening to music, all other noises coming from outside are a
04:12noise or a disturbance for us.
04:17For example, if we are talking to a person, all other unwanted sounds like other people
04:24talking, dogs barking, traffic sounds, or disturbances or noises for us.
04:33Noise pollution What is noise pollution?
04:39Noise pollution is the access of noises that are unpleasant to hear and harms the delicate
04:45internal organs in the ear, and can even lead to loss of hearing, psychological imbalance,
04:52and even heart diseases in humans.
04:56Noise pollution also affects normal animal behavior as they are no longer able to listen
05:01to the voice of prey, and it hinders the prey-predator relationships in natural habitats.
05:11Source of noise pollution can be traffic on roads, railways, air traffic, industrial
05:17noises, concerts, etc.
05:21Industrial areas, airports, railway stations should not be too close to the residential
05:29areas in order to prevent noise pollution in residential areas.
05:35We should wear earplugs.
05:38When you are in an area where there is too much noise pollution.
05:43So friends, today we learned more about sound, and we also learned what is noise.
05:51Now you may go ahead and take a quiz to learn more.
05:54Bye-bye!