Sound

• The speed of sound is dependent on the properties of the medium it travels through.
• Sound waves are longitudinal, meaning they compress the medium through which they travel.
• Sound waves can travel through solids, liquids, or gases but not vacum.
• In solids, sound waves are transmitted by vibrations that propagate along the atoms/molecules of the solid material so as they are closer together sound travels faster.
• In gases, sound waves are transmitted by alternating regions of high and low density (pressure) that propagate through the gas.
• Sound is transmitted in air by a succession of compressions and rarefactions
• Sound is transmitted in air as a succession of compressions and rarefactions. Explain what is mean by succession of compressions and rarefactions ?


  Sound create regions of high pressure and low pressure as it travels.
• Reflection of a sound wave is call an echo
• Amplitude is related to loudness. The bigger amplitude the louder the sound.
• Sound is a mechanical wave as it require a medium to propagate.
• Frequency is measured in Hertz (Hz). One hertz means one cycle per second.
• Speed is how fast a wave travels through its medium. Speed = frequency x wavelength
• The human ear can hear sounds with frequencies between about 20 Hz and 20,000 Hz.
• Wavelength is related to pitch. The shorter the wavelength the higher the frequency, this means wavelength is inversely proportional to pitch.
• Frequency is related to pitch. The higher the pitch (the shorter wavelength), the higher the pitch.