The following is an excerpt from HearingTelephones.com, an informative site sponsored by Elder Depot. Much more information is available on the site including guides on Digital Vs. Analog, Bacteria on Phones, and much more.
What is an Amplified Telephone?
An Amplified Telephone is one that is specially designed to make Sound more ‘Hearable’. Most Basic Amplification increases the Volume or Loudness of Sound. More Advanced Amplification modifies Tone and filters out Background Noise.
Outgoing Sound Amplification?
Most Amplified Telephones only augment Incoming Sound to help the Hard of Hearing but Outgoing Sound Amplified Telephones are also available to help those with soft voices.
Geemarc® AMPLI555 Amplified Phone +12dB Clarity® XLC2+™ Cordless 50dB Amplified Phone +15dB Clarity® Alto Amplified Phone +15dB Clarity® Alto Plus Amplified Phone +15dB Geemarc® AMPLI550 Amplified Phone +15dB Speech Amplified Handset +26dB
How loud is a Decibel?
The reason this question often goes unanswered is complicated and involves logarithmic equations. Skipping the mathematical details, the reason that we can only answer this question with approximations is because every person hears differently and every Sound is unique.
Approximate Decibel ‘Loudness’ 0dB The Softest Sound any Human Ear can Hear. 5dB – 15dB Gentle Breeze 15dB – 30dB Whispered Conversation 30dB – 40dB Quiet Country Home 40dB – 50dB Quiet City Home 50dB – 70dB Normal Conversation 70dB – 90dB Times Square, New York at Noon 75dB – 90dB Typical Automobile Assembly Line 90dB – 100dB Riding a Power Lawn Mower 90dB – 100dB Sitting in the Front Row of Full Orchestra
playing William Tell Overture.
110db – 115dB Thunder, from less than a Mile 115dB – 130dB Sitting in the Front Row of a Metallica concert. 120dB – 130dB Sound begins to cause Physical Pain.
This point varies depending on the frequencies a person can hear.
130dB-150dB Jet Engine at Full Throttle from a few Yards.
Decibels, Amplification, and Loudness.
Roughly, the Loudness of a Sound is Doubled with each increase of 10dB. This means that the Loudness of a Sound increases exponentially along the Decibel scale; +10dB would be approximately Twice as Loud, +20dB would be approximately Four Times as Loud, +30dB would be approximately Eight Times as Loud, +40dB would be approximately Sixteen Times as Loud, +50dB would be approximately Thirty-Two Times as Loud, and so on.
The goal of most Amplification is to increase Normal Conversation (50dB to 70dB) to a Loudness that can be heard by the Hard of Hearing. Amplification of 12-26dB usually suffices for Mild Hearing Loss, 30-40dB usually suffices for Moderate Hearing Loss, and 43-67dB usually suffices for Severe Hearing Loss.
Degrees of Hearing Loss Mild Hearing Loss Moderate Hearing Loss Severe Hearing Loss Cannot hear Soft Sounds.
May mishear Spoken Words.
Background Noise sometimes drowns out Speech.
Cannot hear Normal Sounds.
Often mishears Spoken Words.
Background Noise often drowns out Speech.
Only Loud Sounds can be heard.
Cannot understand Spoken Words.
12-26dB Amplification 30-40dB Amplification 43-67dB Amplification
Advanced Amplification Technology
Digital Clarity Power ™
Certain Clarity Amplified Telephones feature Digital Signal Processing technology that was first used in hearing aids in 1987 and has since become the industry standard. Clarity was the first to incorporate this patented technology into Amplified Telephones.
Digital Clarity Power™ uses Multiband Compression to determine which incoming sounds are the Human Voice and provide more amplification to those sounds while suppressing background noise. It also features Acoustic Noise Cancellation to reduce echoing, Noise Reduction to filter out static, and Voice Clarity to clarify outgoing sound as well as incoming.
High-Definition Sound (HDS)
Certain Serene Innovation Amplified Telephones feature High-Definition Sound technology.
UltraClear™ and ClearDigital™
Certain ClearSounds Amplified Telephones feature UltraClear™ tone management technology and others feature ClearDigital™ Full Digital Power technology.
Telephone Amplifier Units
Amplifier Units that connect to standard Telephones are also available, allowing one to continue using their old phone while still receiving the benefits of amplification.
Hearing Aid Compatible
Many Amplified Telephones are Hearing Aid Compatible. Some are also Telecoil (T-coil) compatible allowing them to be directly connected to many hearing aids; this further helps to filter out background noise.