We use the amazing human ear everyday to listen to different sounds for many reasons. For example we listen to conversations, we listen to music, and we even listen to common everyday sounds such as the birds and rain. However, did you know that our ears have their limits and not everyone is the same? There are levels of sound that affect us differently. The questions I want to answer are: “What level of sound is considered as a normal part of our everyday life and what level goes beyond” and “Why do some sounds lead to permanent damage and others do not? I want to begin by showing different ways that sound is weighed or recorded and compared.
Amplitude is “the quality of being ample in size’’ or “the maximum extent of a vibration measured from the position of equilium”. Constructive Interference is “the conditions of the crests of two waves reaching a point at the same time so they reinforce one another”. Constructive interference can also be described as “the interference of two or more waves of equal frequency and phase resulting in their mutual reinforcement and producing single amplitude”.
Destructive Interference, however, can be described as “the interference of two waves of equal frequency and opposite phase, resulting in their cancellation where the negative displacement of one always coincides with the positive displacement of the other. ” A decibel is “a unit for measuring the relative intensity of sounds, equal to 1/10 of a bel” or “a unit used to measure the intensity of a sound or the power level of an electrical signal by comparing it with a given level on logarithmic scale. Frequency is “the rate of occurrence” or “the rate at which something occurs or is repeated over a particular period of time or in a given sample. ” Harmonic constitution “has to do with harmony as distinguished from melody and rhythm” or “music relating or denoting a harmonic or harmonics. ” Pitch is “the quality of sound governed by the rate of vibrations producing it; the degree of highness or lowness. ”
Propagation is “the travel of electromagnetic or sound waves through a medium such as air or water. Rare faction is “diminution in the density of something air or a gas. Refraction is “the process of burning or bending sound waves, a stream of electrons when passing from one medium to another of different density,” or can be described as “change in direction of propagation of any wave as a result of it’s traveling at different speeds at different points along the wave front. ” Sound wave is “any of longitudal progressive vibrations of a material medium by which sounds are transmitted. ” Wave length is the distance between on peak or crest of a wave of sound and the next corresponding peak or crest.
Hertz unit frequency is the cycle per second the vibrations reaches the inner ear and transmitted through the air that makes sound. Longitudinal wave is sound wave molecules that carry sound. It moves back and forth parallel to the direction of wave motion. Next I want to show how sound in perceptual characteristics can be described in pitch, loudness (or intensity) and quality (or timbre). Sound’s physical characteristics are frequency, amplitude, and harmonic constitution or waveform. Amplitude of a sound wave equals the degree of motion of air molecules in the wave.
The greater the amplitude results in harder molecules hitting the ear drum and the louder it is heard. Distance of sound that can be heard is depends on the intensity. Sound is nine times intense at distance of one unit as a distance of three units- intensity varies at the square of the distances. Sound changes in physical properties in the air such as temperature pressure and humidity resulting in scattering and damping of the directed sound waves. Finally I want to show how sound as a vibration can move through a gas, liquid, or a solid object.
An object that changes or moves shape quickly is a sound’s source. For example; if you hit a tuning fork then it vibrates in midair. When one side of the fork moves one way it pushes little molecules that are in the air and this increases pressure. High pressure is called compression. However, when the fork moves inward it pulls the molecules, this decreases pressure. Low pressure is called rarefaction. Without the molecules pushing each other with high or low pressure, sound could not travel. How we hear the sounds can be explained in seven steps. ) Sound waves enter the ear and travel through a passageway called the ear canal which leads to the eardrum. 2) The eardrum vibrates from the sound waves and sends these vibrations to the tiny bones in the middle ear called the malleus, incus, and stapes. 3) The bones increase the sound vibrations and send them to the inner ear (cochlea). An elastic membrane (basilar) runs from the beginning to the end of the inner ear splitting it into upper and lower parts. 4) The sound vibrations cause the fluid inside the inner ear to ripple and make traveling wave forms along the basilar membrane.
Hair cells sit on top of membrane to “ride the wave”. 5) As hair cells move up and down their bristly structure bump against a membrane and tilt to the side. This action causes pore-like channels, which are on the surface of the bristles, to open up and certain chemicals rush in when that happen creating an electrical signal. 6) The Auditory nerve carries this electrical signal to the brain and translates it into a sound that we recognize. 7) Hair cells near the base of the inner ear detect high pitch sound. Those nearer the centermost point detect low pitch sound.
