Sound

• Sound travels in the air as longitudinal waves, which are vibrations that travel in the same direction as the wave
• Space is a vacuum. A vacuum is somewhere where there are no particles
• Sound travels faster the closer particles are.
• Pitch- the frequency of a sound wave, measured in Hertz (Hz)
• Loudness- the loudness of a sound is determined by the amplitude of the sound wave.
• Wavelength is the distance from a point on one wave to the same point on the next wave e.g. peak to peak
• Frequency = Number of waves/Time
• Amplitude is the maximum displacement of a wave from its equilibrium position(the middle line).
• Period of a wave = Time taken for one complete wave to pass a point.
• Transverse waves are waves that vibrate perpendicular to the direction of energy transfer.
• Most human ears can hear frequencies between 20 and 20,000 Hz. Any frequency over 20,000Hz is known as ultrasound. Frequencies under 20Hz are known as infrasound.
• The speed equation is: speed = distance / time.
• Wave speed = frequency x wavelength (m/s) also known as v = f x lambda
• The human ear

  
• Outer ear or Pinna: the external part of the ear in humans and other mammals; the auricle.
• Ear canal: A passageway that connects the external ear to the middle ear.
• Ear drum: A thin membrane that separates the outer ear from the middle ear. It vibrates when sound waves pass through it.
• Hammer or Malleus: One of the three tiny bones that make up the middle ear. It moves when the eardrum vibrates.
• Anvil or Incus: The second tiny bone in the ear. A small, hollow, oval-shaped bone that is the base of the eardrum. It is moved by the hammer
• Stirrup or Stapes: The third tiny bone in the ear. It is moved by the anvil.
• Cochlea: Spiral tube. When the stirrup moves, fluid inside the cochlea moves. Hearing receptors turn the fluid into sound signals
• Auditory nerve: Carries messages from the cochlea to the brain. The brain makes sense of these signals as sounds.
• Oscillate is to vibrate or move back and forth in a regular way
• Vibrate is to vibrate, to shake, to move in a vibration
• Sound can travel through solids the fastest because the particles are close together and vibrate more quickly
• Sound particles travel by vibrating particles in the air, which are called air molecules.
• Echo location works by sending out a sound wave and listening for the time it takes to return and halving the time which gives the distance of how far away the object is
• Bats use echolocation by emitting high-pitched sounds and listening for echoes
• Ultrasounds are used for pregnancies by adding a gel to the skin and placing a transducer on the skin. We place the gel so that it is easier for the sound waves to travel through the skin. We then measure the time taken for the sound waves to reach the fetus. The computer then halves the time taken and uses the measurement to produce a picture of the fetus.
• Longitudinal waves have a vibrating particle that oscillates parallel to the direction of the wave.