Hearing is a remarkable sense that most of us take for granted–but not everyone can. Due to physical damage or simple aging, many people have lost some or most of their hearing.
Enter the hearing aid, a device for amplifying sound and directing it into the ear. The original hearing aid was the hand cupped behind the ear, a simple technique that can amplify sound by five to 10 decibels.
Sometime around the 17th century, the ear trumpet appeared. Originally used by sailors for communicating over long distances, they were soon adopted by the hearing-impaired. By the end of the 19th century a large variety were available, ranging from elaborate works of art to cheap tin and rubber models. (The cheap ones worked just as well as the expensive ones.)
The best ear trumpets could amplify sound by 10 to 20 decibels. Large, heavy ones, too awkward for daily use, could double that, but were still only helpful for people with mild hearing loss. As well, they could only amplify a small part of the normal frequency range of the human voice.
The first electrical hearing aids, introduced around 1900, grew out of the development of the telephone. They were bulky things consisting of a microphone, a vacuum tube, a battery, an earphone and volume and tone controls. The earliest ones could only amplify sound about as much as an ear trumpet, but could amplify a much wider range of frequencies.
Hearing aids shrank with the invention of the transistor in 1948 (which did away with the vacuum tube) and have kept shrinking. Until the mid 1980s, they amplified all sound by the same amount, which meant sudden loud sounds usually sent the wearer scrambling for the volume controls. Better volume controls for loud and soft sounds and high and low frequencies were introduced in 1985.
Then, just three years ago, the first digital hearing aids came on the market. Rather than turning air vibrations into a varying electrical current which could be boosted, then used to drive a speaker, they turned the sound waves into binary numbers which could first be processed by a microchip. The difference, users say, is like the difference between listening to a tape and a CD.
Now Danavox, a leading manufacturer, is about to take digital hearing aids one step further. They’re releasing a new kind of smart hearing aid, called the Danalogic, that is nothing less than a programmable computer, much like your own PC, that you put in your ear.
When released, the Danalogic will have four software packages, but more are being developed and can be installed just as you would load a program into your PC. Eventually, hearing aids may become fairly standard pieces of hardware, all sharing the same operating system, for which software manufacturers will create a variety of programs.
I don’t know if that’s good or bad news for hearing aid manufacturers, but it’s definitely good news for the people who wear hearing aids. The Danalogic offers several major advances. Because it breaks down the sound waves it receives into 14 bands (as opposed to just four in other hearing aids), it can discern between speech and noise–and amplify the speech while suppressing the noise. It can also tell the difference betwee soft sounds and loud sounds, and amplify soft sounds without amplifying loud sounds, eliminating the need for any kind of manual volume control.
The Danalogic can also locate all the sound sources around the wearer’s head, and reduce all those that are more than 15 percent off center, ensuring the wearer hears most clearly the sounds from what he’s currently looking at.
Finally, the Danalogic also features the unique ability to detect feedback before it begins and generate a signal that cancels it out. That means no more whistling–something people who don’t wear hearing aids, as well as those that do, can heartily applaud.
If, at this point, you’re wondering what all this talk about hearing aids has to do with you, since you’re young and have perfect hearing, well, I hate to break the news to you, but we’re all getting older. If it doesn’t matter to you yet, it may very well matter someday sooner than you think–and then you’ll be grateful that the digital revolution is finally beginning to find its way into our ears.
