|The SongFinder is an advanced digital device aimed at bird enthusiasts who suffer from high frequency hearing loss and who are unable to hear high-pitched bird songs in their natural surroundings. Unlike conventional amplifying-type hearing aids, the Songfinder works by lowering the frequency of high-pitched songs into a range where the user has normal or near-normal hearing. This method avoids the many pitfalls of extreme amplification. Furthermore, the SongFinder is a two-channel "binaural" device that allows the user to determine the directions and distances of singing birds. The SongFinder offers an elegant and tasteful solution for aging birders and other nature lovers who can no longer hear high singing birds..
As we grow older, we experience diminished sensitivity to high frequency sounds. Youthful hearing extends as high as 20,000 Hz (Hz = cycles/second). However, the average person (especially among men) over fifty years of age has completely lost the very highest frequencies and often suffers moderate hearing loss in the range from 4,000 to 10,000 Hz. Moderate to severe hearing loss above 4,000-5,000 Hz becomes the norm for many individuals living sixty and beyond.
Loss of hearing with age, technically referred to as "presbycusis," is a widespread phenomenon that seemingly cannot be avoided. To make matter worse, prolonged exposure to loud music and other loud background sounds also results in reduced sensitivity in the high range. This is NOT good news for aging birdwatchers!
The average frequency of the songs of songbirds is about 4,000 Hz, approximately the same pitch as the highest note of a piano. Many warblers, sparrows, waxwings, kinglets, and a number of other birds produce sounds that reach 8,000 Hz and beyond. Moderate to severe hearing loss in the 3,000-10,000 Hz range greatly reduces the ability of a birder to be aware of the presence of these high-pitched singers (Note: most insect songs are at frequencies above 4,000 Hz. Thus, high frequency hearing loss will have a profound impact on one's ability to hear insects).
THE TRADITIONAL SOLUTION: AMPLIFICATION AIDS
The traditional approach to counteracting hearing loss has been to utilize amplifying hearing aids that raise the amplitude of incoming signals to levels where they can be heard. This approach works well in the realm of speech perception (mostly below 3,000 Hz) but has limited application for birders and other nature lovers who are deaf to high-pitched bird songs but who have little trouble hearing speech. For aging birders, conventional amplifying-type hearing aids are usually a major disappointment. Some of the problems encountered with such devices are summarized as follows:
1) There is a limit to how much a hearing aid can amplify before feedback squeal occurs. If hearing loss is severe, maximum amplification will not be adequate to allow high bird songs to be heard at reasonable distances in typical outdoor situations.
2) Conventional aids generally do not produce good amplification above 5,000 Hz. Thus, most amplifying hearing aids offer little or no help with the highest singing birds and a great many insects.
3) Extraneous sounds such as wind noise or the sounds that accompany walking through leaves or stepping on twigs are also amplified and can be extremely annoying. Users often complain of "sensory overload" due to the continuous high-level amplification of such environmental sounds.
4) Even when users wear amplifying aids in both ears, the ability to determine distances and directions of incoming sounds is normally much reduced. The three dimensional or binaural aspect of hearing is lost and it becomes difficult, if not impossible, to find birds, even when they are heard.
THE SONGFINDER: A FREQUENCY SHIFTING SOLUTION
After 20 years of experimentation with a variety of devices, we have developed the SongFinder,a digital instrument that is designed specifically for birders and other nature enthusiasts suffering from high frequency hearing loss, but who still have reasonably normal hearing in both ears up to around 2,000-3,000 Hz. As a reference point, if you have little trouble holding conversations with other people, then you probably have good hearing through 2,000 Hz.
The SongFinder works on a frequency dividing principle. Incoming bird sounds above 3,000-4,000 Hz are converted into digital signals that are acted upon by an internal DSP (digital signal processor) that is driven by mathematical algorithms that accomplish frequency division. As a result, high bird sounds are lowered into a frequency range where one still has normal or near-normal hearing. The user chooses the degree of lowering, reducing the frequency of incoming high-pitched sounds by one-half, one-third, or one-quarter. For example, a bird sound of 8,000 Hz will be perceived as 4,000 Hz when halved or 2,000 Hz when quartered. Using the SongFinder set to one-quarter, a person with severe high frequency hearing loss will often be able to hear ALL the highest singing birds!
The SongFinder responds only to high frequency sounds above around 3,000-4,000 Hz (depending on which user-selectable high pass filter setting is chosen). It is not based on an amplifying principle. Rather, the high-pitched sounds are lowered and then added, at normal amplitude or at slight to moderate amplification, to what one already hears. Since extreme amplification is never involved, extraneous sounds like the snapping of twigs do not become annoying. Sensory overload is completely avoided, feedback squeal does not occur, and the overall effect is gentle and natural.
Furthermore, the SongFinder is a two-channel "binaural" device that allows the user to determine the locations of singing birds. A small, loose-fitting binaural headset is worn which positions tiny micophones next to each ear. The two microphones pick up incoming high-pitched sounds and route them to the device that is stored in a shirt pocket or hung around the neck with a carrying strap. The two separate channels of high-pitched sounds are lowered and then fed back to each ear via miniature earphones that do not impair normal hearing.
The result is a lifelike, three-dimensional binaural perception that allows the user to judge directions and distances of incoming sounds with amazing accuracy. Such pitch lowered nature sounds are perceived as natural and real, and the user is able to determine the whereabouts of the soundmakers in the outdoor environment.
IS THE SONGFINDER RIGHT FOR YOU?
The SongFinder is designed for those suffering from moderate to severe high frequency hearing loss in the higher ranges, but who still have reasonably good hearing up to around 2,000-3,000 Hz in both ears. Such individuals are almost completely deaf to high-pitched bird songs but will be able to hear human speech and low singing birds such as whip-poor-wills, robins, and cardinals without the need for special hearing aid devices. While the SongFinder is primarily a pitch-lowering device, it also offers a reasonable degree of amplification of the lowered signals.
Potential buyers might prefer to obtain an audiogram from a competent audiologist. Have the audiologist pay particular attention to high frequency response. Look for moderate to severe hearing loss above 4,000 Hz with normal or near-normal hearing up to at least around 2,000 Hz. If there is moderate loss at 2,000 Hz, the utility of the SongFinder will be somewhat reduced, although some people have used the SongFinder successfully in conjunction with amplification-type aids that provide the needed boost in the low range.