Please enable JavaScript.
Coggle requires JavaScript to display documents.
how are sounds produced (how do we hear sounds (how does sound reach your…
how are sounds produced
how are sounds produced
-
when objects vibrate, they move backwards and forward very quickly
eg, sound produced by bee is made by rapid vibrations of wings, male grasshopper makes sounds by rubbing leg against wing, roar of lion is produced by vibration in throat. land mammals produce sounds in throats
what is frequency
number of vibrations per second is called frequency which is measured in hertz (Hz). frequency of 100 Hz means 100 vibrations per second
-
what is speed of sound
-
speed of sound depends on density of medium (material). denser the medium, faster sound travels. sound can also travel further in denser medium
-
-
-
how do we hear sounds
-
however, we cannot see waves in air. we can only detect them as sound when they reach our ears
pg 137
when prong of tuning fork vibrates, it causes surrounding air molecules to vibrate. these molecules interact by colliding with their neighbours and causing them to vibrate, and so on. in this way, energy from tuning fork is passed along molecule to molecule until it reaches our ears
-
although sound energy moves from vibrating object to our ears, air molecules themselves do not move to the ear; they just vibrate, that is, move beckward and forwards passing energy along
-
range of hearing
human ear detects only limited range of sound frequencies. it cannot detect very low frequencies or very high frequencies.human ear can only detect sounds from about 20Hz to about 20000Hz. this is called range of hearing
different people have different ranges of hearing, for eg, younger people can hear sounds of higher frequencies better than older people
-
sound and music
-
string instruments
strings vibrate to produce sounds. pitch of note depends on 3 factors: length, tension, and thickness of string.
wind instruments
produce sounds when we blow into them. blowing causes column of air in instrument to vibrate and produce sounds. short column of air produces notes of high pitch. long column of air produces low pitch
-
-
-
-
effects of noise
-
-
-
loudness of sound is measured in decibels (dB) using decibel meter.softest sound that anyone can hear is 0dB louder sound has more energy. pg 144
noise pollution
traffic noise, construction sites, loud music, noisy machines and barking dogs etc
affects human health: indigestion and heart diseases, disturb sleep patterns
-
continued exposure to noises above 5 dB can damage ears and cause deafness.loud noises can damage inner ear and nerve endings joined to it