Sound: overview
● Sound starts as vibrations. The bigger the vibrations, the louder the sound. Sound
vibrations travel from their source in all directions. This transfers energy.
● Vibrating particles make the particles next to them travel/vibrate. The Birating
particles make up a sound wave. In sound waves, the vibrations and energy
echoes are in the reflected direction.
● Sound waves are an example of Longitudinal waves.
● When a sound wave hits a hard surface, it bounces off the surface. The wave has
been reflected. This is what makes echoes.
● Frequency is the number of waves per second.
● Wave length is the difference between waves.
● When the wavelength is bigger, the frequency is lower.
● The average hearing of a human is from 20Hz to 20000Hz ( 20 kilo)
● Frequency is measured in Hertz (Hz)
Speed Of Sound:
, 𝐷𝑖𝑠𝑡𝑎𝑛𝑐𝑒 𝑡𝑟𝑎𝑣𝑒𝑙𝑙𝑒𝑑
Average speed =
𝑇𝑖𝑚𝑒 𝑇𝑎𝑘𝑒𝑛
● Sounds travel faster through liquids and solids than it does through air and other
gases.
● This is because the particles in a solid are closer than the particles in a gas.
● The closer the particles are, the faster the sound waves travel.
The ear:
We can detect sound using our ears. An ear has an eardrum inside, connected to three
small bones. The vibrations in the air make the eardrum vibrate, and these vibrations
are passed through the three small bones( called ossicles ) to a spiral structure called
the cochlea. Signals are passed from the cochlea to the brain through the auditory
nerves, and our brain interprets these signals as sound.
Sound waves carry energy into your ear. This makes your eardrum vibrate.
Your eardrum passes on the vibrations to the tiny bones in your ear - The ossicles
Ossicles
Hammer Anvil Stirrup
The Vibrating ossicles transfer energy to the Cochlea.
Here, the tiny vibrations travel through a liquid.
Tiny hairs - Cilia- hang down into the liquid. Vibrations travelling through the liquid push
the air.
, Nerve cells on the hair detect this movement.
They send signals to the brain.
You hear the sound.
Very loud sounds push the hair too far and the hairs are damaged.
Noise:
Noise is an unwanted sound. Noise damages our hearing.
We can measure how loud a sound is by using a sound intensity metre. This is an
instrument which measures the loudness of the noise.
Soft materials can absorb sound.
Summary notes on sound:
★ What is the difference between pitch and volume?
Pitch is related to the frequency whereas volume is how high or soft something
sounds.
★ Light travels faster than sound
● Sound starts as vibrations. The bigger the vibrations, the louder the sound. Sound
vibrations travel from their source in all directions. This transfers energy.
● Vibrating particles make the particles next to them travel/vibrate. The Birating
particles make up a sound wave. In sound waves, the vibrations and energy
echoes are in the reflected direction.
● Sound waves are an example of Longitudinal waves.
● When a sound wave hits a hard surface, it bounces off the surface. The wave has
been reflected. This is what makes echoes.
● Frequency is the number of waves per second.
● Wave length is the difference between waves.
● When the wavelength is bigger, the frequency is lower.
● The average hearing of a human is from 20Hz to 20000Hz ( 20 kilo)
● Frequency is measured in Hertz (Hz)
Speed Of Sound:
, 𝐷𝑖𝑠𝑡𝑎𝑛𝑐𝑒 𝑡𝑟𝑎𝑣𝑒𝑙𝑙𝑒𝑑
Average speed =
𝑇𝑖𝑚𝑒 𝑇𝑎𝑘𝑒𝑛
● Sounds travel faster through liquids and solids than it does through air and other
gases.
● This is because the particles in a solid are closer than the particles in a gas.
● The closer the particles are, the faster the sound waves travel.
The ear:
We can detect sound using our ears. An ear has an eardrum inside, connected to three
small bones. The vibrations in the air make the eardrum vibrate, and these vibrations
are passed through the three small bones( called ossicles ) to a spiral structure called
the cochlea. Signals are passed from the cochlea to the brain through the auditory
nerves, and our brain interprets these signals as sound.
Sound waves carry energy into your ear. This makes your eardrum vibrate.
Your eardrum passes on the vibrations to the tiny bones in your ear - The ossicles
Ossicles
Hammer Anvil Stirrup
The Vibrating ossicles transfer energy to the Cochlea.
Here, the tiny vibrations travel through a liquid.
Tiny hairs - Cilia- hang down into the liquid. Vibrations travelling through the liquid push
the air.
, Nerve cells on the hair detect this movement.
They send signals to the brain.
You hear the sound.
Very loud sounds push the hair too far and the hairs are damaged.
Noise:
Noise is an unwanted sound. Noise damages our hearing.
We can measure how loud a sound is by using a sound intensity metre. This is an
instrument which measures the loudness of the noise.
Soft materials can absorb sound.
Summary notes on sound:
★ What is the difference between pitch and volume?
Pitch is related to the frequency whereas volume is how high or soft something
sounds.
★ Light travels faster than sound
