A version of this blog post by Stephen Hunter was published last year in The Searcher magazine and his sound advice is reproduced here in order to reach a wider audience. Pun intended!
I have noticed the lack of information available on linking hearing aids to everyday technology, including metal detectors. A hearing impaired detectorist recently contacted me seeking help on options available to him. He found the advice I gave helpful, so I have decided to share the information with Searcher readers in the hope that it might help others in a similar predicament.
My qualifications? I work as a National Health Service (NHS) audiologist and have been interested in detecting for many years. In my line of work I help hearing-impaired people on a daily basis, helping them to find ways of coping with a hearing loss when carrying out normal day- to-day activities whilst wearing hearing aids. My job involves diagnosing hearing loss and the fitting and repair of aids for youngsters right up to the elderly.
First, I’d like to start by giving you some background information. A progressive hearing loss (Presbyacusis), which we all experience to some degree as we grow older, is a result of a deficit that occurs in two areas. There is hair cell damage in the cochlea (the hearing organ itself) and also damage that occurs in the neural pathway that leads from the cochlea to the brain. With this type of loss there are two issues, the clarity of sound and the audibility. A hearing aid alters the characteristic of the sound heard and increases audibility, but it cannot fine tune or offer more resolution to sharpen the sound – this can only be done well in a normal functioning cochlea.
How does this relate to hearing target sounds from your detector?
Generally speaking you will typically get a high frequency sloping hearing loss with Presbyacusis, which results in a progressive loss across the frequency range. In a multi-tone metal detector (for example), it is more likely that a hearing impaired person will hear higher pitch frequencies greatly reduced or none at all. There is also a chance that the audibility of other sounds is affected, depending on how severe the loss.
You will also have issues when using machines like (for instance) the Minelab E-Trac or CTX 3030. The little flute-like notes that are trying to allow you to discriminate whether to dig or not may not be heard with the same quality or resolution as intended.
What are the options available to me?
If you wear a traditional or behind the ear (BTE) type NHS aid, there are often connectors called Direct Audio Input shoes (see illustration) that can be purchased for your make and model of aid. This allows you to run a wire from the bottom of the aids straight into the 1/4” headphone jack of the detector. The main advantage of these are that you will have the sound of the tones from the detector adjusted to suit the individual’s hearing loss so it should be a more true sound than just wearing headphones on their own, i.e. without a hearing aid.
Another option would be to use a device called a Portable Neck Loop. These are available in wired or Bluetooth form, and are simply a loop device worn around the neck allowing sound from a headphone jack to be streamed to hearing aids by using a special T (Loop Setting) on the hearing aid.
Most hearing aids can have this feature added with a request to the Audiology Department/Hearing Aid Dispenser you attend. Although the Bluetooth version would seem the more sleek of these alternatives I’d imagine it may cause a slight time lag between signal detection and transmission of the audio sound so be aware that the wired option could work out the safer option to go for.
Is there anything I could change on the detector to better equip me to hear target audio?
Other changes can be made, like modifying the detector settings to single tone setup so that no potentially good targets are missed. It may mean sacrificing some of the tonal information that the detector is trying to put across to the user but it is better than leaving it to chance whether the tone is heard or not at all.
Another option would be to get your local Audiology Department/Hearing Aid Dispenser to explain your hearing loss in more depth to you so that you also will have the information on what frequencies are causing you particular problems. Portable Neck loop systems and Direct Audio Input Shoes with Leads are available for most makes and models of NHS and private hearing aid through: www.deafequipment.co.uk
The equipment mentioned is mainly available for the Behind The Ear (BTE) range of hearing aids but given size constraints of the In The Ear (ITE) type aids the additional device options are somewhat more limited. For this reason it is always best to check with your Hearing Aid Dispenser or NHS Audiologist first before purchasing.
A final word …
There are a few other things to consider when thinking about using hearing aids with a metal detector. They are the length of time that you detect, the impact this can have on your hearing and the effect detecting over long periods can have on Central Processing of sound in the brain.
As a general rule the volume of the headphones or target tones in the hearing aids should not be at a level that you cannot hear someone talking beside you. We have all been in the situation where we have become entranced in listening to all those beeps in the hope of detecting that ‘good signal’ so whack up the volume.
High intensity sounds over a short period or lower level sounds over a longer period can be just as damaging to the hearing thresholds so rest periods between detecting is always recommended where possible.
For more exact dB levels and Time Periods See Noise at Work Regulations: http://www.hse.gov.uk/noise/regulations.htm
Detecting and pursuits with prolonged exposure to noise may cause permanent hearing damage if care isn’t taken. The associated tiredness from long detecting sessions also plays an important role in reduced concentration in the central auditory processing pathways in the brain.
Your brain needs to make sense of the sounds it receives when detecting. Over long periods searching we appear to lose our abilities to process and discern sounds as sharply as we would when listening to them at the start of a session. The physical hearing ability is still present but as our concentration is not at its best, tones will be dismissed instead of interrogated further.
This could very well be that elusive gold hammered or crotal bell you have always had on your wish list, so it is certainly something to think about! With the help of some of the devices shown, it may help those affected achieve better success in those environments.
Hopefully this has been of some help to those of you who wear hearing aids and detect. Connevans design, manufacture and supply equipment for deaf and hard of hearing people in education, employment, leisure and the home. Check out their website http://www.deafequipment.co.uk
Another option to mention is the Nokta FORS CoRe, a relatively new machine to the market, whose handle vibrates when passed over a signal. The vibration works in conjunction with the Discrimination setting.
EQUINOX USERS SEE HERE