Sound waves

• A sound wave is a vibration that travels through a solid, liquid or gas such as the air or water.
• A loud sound has a large amplitude, a high pitched sound has a high frequency.
• When there is a sound wave, the air particles don't travel directly from the object making the sound to your ear. Sound waves are vibrations being passed on between particles.
• The loudness of a sound depends on how big the vibration of the air is.
• The pitch of a sound is how high or low the sound is. A high pitch sound has faster vibrations and higher wave frequency. A low pitch has slower vibrations and a lower wave frequency.
• Frequency is the number of vibrations of the wave in one second, also seen as the number of complete waves passing a point in one second. Frequency is measured in hertz (Hz).
• A transverse wave is a wave in which the particles move up and down at right angles to the direction it travels in, like an ocean wave or lifting a rope up and down.
• A longitudinal wave is a wave where the particles move forwards and backwards in the direction that the wave travels.
• Amplitude is the height of the top of a wave from its resting position. The greater the amplitude, the taller the wave (and the louder the sound if a sound wave).
• Sound travels at different speeds through gases, solids and liquids.
• You hear an echo when a sound wave reflects off a surface and reaches your ear.
• You can work out the speed of sound using the equation: Speed = distance / time
• Sound can travel through anything made of particles.
• You hear an echo when a sound bounces off something and comes back to your ear.
• An echo is made by a sound wave reflecting off a surface.
• We can hear sounds because our ears turn sound vibrations from the air, into signals that are sent to our brain.
• We can't hear all levels of sounds. Sound waves with very high frequencies are called ultrasound and our ears can't detect them.
• The eardrum is a thin flap of skin that is stretched tight like a drum
• The ear bones are three small bones called the hammer, anvil and the stirrup.
• The cochlea is a spiral shaped part of the ear that looks a bit like a snail shell.
• The auditory nerve is the nerve that carries signals from the cochlea to the brain.
• The pinna is the visible portion of the outer ear,
• When a sound reaches us, the air particles inside our ear canal vibrate and hit the eardrum.
• The eardrum then starts vibrating and these vibrations are passed to three small ear bones.
• The stirrup bone hits the cochlea, which turns the vibrations into an electrical signal that is sent to our brain via the auditory nerve.
• When the signal reaches our brain, our brain translates the signal into the sound we hear.
• Humans have a sound frequency of 20,000 Hz.