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EMAILWIRE.COM, February 07, 2015 ) Dallas, Texas -- Personal alarms are a way to practice passive
self-defense. A personal alarm is a small, hand-held device that emits strong, loud, high-pitched sounds to
deter attackers because the noise will sometimes draw the attention of passersby. The sound emitted can also have the effect of distracting, disorienting, or surprising the assailant.
It is activated either by a button, or a tag that, when pulled, sets the siren off. The volume varies from model to model, with some models having 130 decibels. Some personal alarms are also outfitted with an LED light for normal lighting purposes or to help deter an assailant. Attention must be given to the fact that these devices can give a "false sense of security."
Sound is measured in units called decibels. Sounds of less than 75 decibels, even after long exposure, are unlikely to cause hearing loss. However, long or repeated exposure to sounds at or above 85 decibels can cause hearing loss. The louder the sound, the shorter the amount of time it takes for noise-induced hearing loss (NIHL) to happen. Distance from the source of the sound and the length of time of exposure to the sound are important factors in protecting hearing.
Sounds can be harmful when they are too loud, even for a brief time, or when they are both loud and long-lasting. These sounds can damage sensitive structures in the inner ear and cause noise-induced hearing loss (NIHL).
To understand how loud noises can damage hearing, an understanding of how we hear is needed. Hearing depends on a series of events that change sound waves in the air into electrical signals. The auditory nerve then carries these signals to the brain through a series of steps.
1. Sound waves enter the outer ear and travel through a narrow passageway called the ear canal, which leads to the eardrum.
2. The eardrum vibrates from the incoming sound waves and sends these vibrations to three tiny bones in the middle ear. These bones are called the malleus, incus, and stapes.
3. The bones in the middle ear couple the sound vibrations from the air to fluid vibrations in the cochlea of the inner ear, which is shaped like a snail and filled with fluid. An elastic partition runs from the beginning to the end of the cochlea, splitting it into an upper and lower part. This partition is called the basilar membrane because it serves as the base, or ground floor, on which key hearing structures sit.
4. Once the vibrations cause the fluid inside the cochlea to ripple, a traveling wave forms along the basilar membrane. Hair cells--sensory cells sitting on top of the basilar membrane--ride the wave.
5. As the hair cells move up and down, microscopic hair-like projections (known as stereocilia) that perch on top of the hair cells bump against an overlying structure and bend. Bending causes pore-like channels, which are at the tips of the stereocilia, to open up. When that happens, chemicals rush into the cell, creating an electrical signal.
6. The auditory nerve carries this electrical signal to the brain, which translates it into a sound that we recognize and understand.
Most NIHL is caused by the damage and eventual death of these hair cells.
Loud noise exposure can also cause tinnitus--a ringing, buzzing, or roaring in the ears or head. Tinnitus may subside over time, but can sometimes continue constantly or occasionally throughout a person's life. Sometimes exposure to impulse or continuous loud noise causes a temporary hearing loss that disappears 16 to 48 hours later
Decibel (Loudness) Comparison Chart
Here are some interesting numbers, collected from a variety of sources that help one to understand the volume levels of various sources and how they can affect our hearing.
Environmental Noise
Weakest sound heard 0dB
Whisper Quiet Library at 6' 30dB
Normal conversation at 3' 60-65dB
Telephone dial tone 80dB
City Traffic (inside car) 85dB
Train whistle at 500', Truck Traffic 90dB
Jackhammer at 50' 95dB
Subway train at 200' 95dB
Level at which sustained exposure may result in hearing loss 90 - 95dB
Hand Drill 98dB
Power mower at 3' 107dB
Snowmobile, Motorcycle 100dB
Power saw at 3' 110dB
Sandblasting, Loud Rock Concert 115dB
Pain begins 125dB
Pneumatic riveter at 4' 125dB
Even short term exposure can cause permanent damage - Loudest recommended exposure WITH hearing protection 140dB
Jet engine at 100' 140dB
12 Gauge Shotgun Blast 165dB
Death of hearing tissue 180dB
Loudest sound possible 194dB
Quick Overview
The
Key Chain Alarm with Light combines two deterrents against attack...a 130db alarm and a flashing light.
Details
The alarm is activated when the pin attached to the key chain is pulled or by pressing the alarm button on the top of the unit. The unit can be used as a flashlight without activating the alarm to provide additional
night time safety. Two AAA batteries included.
About Safeguard Defender:
Safeguard Defender is a supplier of a variety of personal safety products
Joshua Villarreal
1-800-859-5566
villa@reagan.comSource:
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