How We Hear - An Overview
As one of the five traditional senses, hearing
, is a very important sense for people to have. People who cannot hear have a condition called deafness. In the past, those who could not hear were often left out of conversations and other social activities.
Thankfully, over 100 years ago, with the advent of electricity, hearing aids were produced, giving those with hearing difficulties a chance to regain their social position and overall enjoyment of life. The modern hearing aid is a superb device that is comfortable to wear, discerning in fashion, and provides the broadest technological advantages for wearers.
The Physics of Sound
Sound is carried through every medium, including liquid, solid, plasma and gas. When transmitted through a solid, it is both a longitudinal wave and a transverse wave. However, when sound is carried through the other mediums, it is only a longitudinal wave, also known as a compression wave. Longitudinal waves are areas of different pressure, deviating from the equilibrium pressure.
In order to classify a sound wave, they should be examined by the general properties of all waves.
Frequency, the number of complete waves in a given period of time.
Wavelength, the distance between wave crests or wave troughs.
Period, the duration of one wave cycle.
Amplitude, change in pressure during one wave oscillation.
Intensity, perceived by the ear as loudness.
Speed, how fast a wave is traveling.
Direction, the shape and path of a wave.
Sound travels rapidly. Not nearly as fast as light, of course, but rapid nonetheless. Sound travels through various mediums at distinct speeds, but this can always be measured by being proportional to the square root of the ratio of the stiffness of the medium to its density. Also, sound travels at different speeds due to the temperature of the medium. Here are a few examples.
In 20 degree freshwater, sound travels at 3,315 mph.
In steel, sound travels at 13,330 mph.
This is a significant difference in how sound behaves in various surroundings.
How loud something is can be referred to as intensity or volume, and volume is measured in a unit of measure called decibels. The significant decibel levels for those thinking about getting a hearing aid are transmitted from common sources like a person speaking or a TV that has been turned on. Here is a list of other sounds and decibel levels.
TV set turned on, 60 decibels
Damage will occur if exposed to this level for a long time duration, 90 decibels
Grenade exploding, 175 decibels
Damage to one's hearing is one of the few things which the human body cannot restore. Once some of the auditory nerves have been damaged, they are not put back or revived.
For humans, sound waves between the frequency range of 12Hz to 20,000Hz can be detected as sound. For animals, the range differs, with dogs being noted for their ability to hear things with a frequency above 20,000 Hz. The vibrations from a sound being created are picked up by the outer ear, and brought into the inner ear where the ear changes pressure waves into nerve impulses. These impulses are sent to the brain and comprehended as sound. A more in-depth knowledge can be gained by looking into the anatomy of the ear.
The process of getting a sound wave to amplifying it to translating it into a form that the brain can understand is rightfully amazing. Hearing aids help the middle ear by magnifying the signal enough for the inner ear to interpret it and send the message to the brain. When the brain receives these signals, it interprets them as the various sounds which we all recognize. The path of sound from source to the outer ear, middle ear, inner ear, and then brain where it is perceived as a sound is a long one. However, because speed travels extremely quickly, and the nerves in the ear receive and send the signal to the brain rapidly, what we see and what we hear are in sync.
An entertaining test of the speed of sound is to watch a baseball game from 300 meters away. You will see the batter swing the bat and make contact with the pitched ball, and then a second later, you will hear the recognizable crack of the bat against the ball.
Alternatives to Hearing
While some people can benefit from hearing aids, others' hearing abilities have been permanently damaged, and hearing aids do not offer much help for them. In order to communicate with others, these people use sign language and lip reading techniques.
Sign language has a long history, with forms of this type of communication dating back thousands of years. This language has various forms as well, coordinating to a group of spoken languages.
If you have lost your hearing, hearing aids are excellent tools of our modern time which should be enjoyed.
by: jenny hearingaid
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