Sound waves

• Sound is produced whne something moves back and froth very quickly.
• When something vibrates, it passes the vibrations to its surroundings. These vibrations create regions of space in which the air is more conpact and more spead out. The waves that less compact are called rarefactions and the ones that are compact are called compressions.
• A sound wave is the movement of alternating compressions and rarefactions.
• Sound relies upon vibrating particles. This means that sound can pass through solids, liquids and gas but not through a vaccuum of space, because there are no particles for the sound to pass through.
• A wave carries energy from one point to another. This can happen in 2 ways. A transverse wave the particles of the wave vibrate up and down whilst the wave travels forward. kinda like a sin(x) curve
• Radiated heat energy is transferres as a type of transverse wave
• A sound wave differs from a transverse wave. In a sound wave, the particles that make up the wave move back and forth in the same direction as the wave is travelling. This type of wave is called longitudinal wave, or a compression wave.
• Sound energy is transmitted through a material as longitudinal waves.
• The particles of the material vibrate as the sound energy transmits through it.
• Sound travels faster through solids than through liquids, and faster through liquids than through gases.
• The temperature of the movement also affects the speed of the sound transmission.
• If a sound wave hits a dense material, made of particles closely packed together, then the compressions and rarefactions will travel quickly.
• The speed sound travels through a material depends on the qualities of the material.
• Sound travels faster through warm air than through cold air and the same for when it comes to liquids.
• Sound passes through thin walls and is transmitted in smaller distances through most materials. Hardsurfaces reflect sound waves. This reflected sound is called an echo. The time fifference between the time a sound is received and sent can be measured by using a technique called sonar(sound navigation and ranging)
• A bare and empty room has multiple hard surfaces whichh reflect sound with little if any absorption. This causes sound to bounce around as many series of echos.
• The length of time a sound can be heard is known as the reverberation. Soft material can absorb sound and convert it into heat.
• High pitched and low pitched sound can be compared by analysing their sound waves using an oscilloscope.
• A sound that vibrates more produces a sound of a higher pitch when compared to the one of a low pitched sound. The number of vibrations a sound makes ecah second is called the frequency of a wave. Frequency is measured in hertz.
• As we age, our ability to hear higher frequencies of sound decreases.
• Young people can typically hear a range of frequencies up to 20000Hz, yet most people over 65 years cannot hear frequencies of about 5000Hz.
• As we age, more of the tiny hair cells in our inner ear become damaged and somewhat destroyed.
• This happens most easily to the hair cells that we use to hear frequency sound and once they are destroyed these cells cannot be repaired.
• Ultrasound is the name given to sound waves with frequencies above our hearing range.
• Frequencies of range that is lower than our range is called the infrasound.
• All musical instrumenst produce sound by vibrations. Ultrasounds waves pass easily through fluids and soft tissues but are reflected from other layers within the body.