How common is hearing loss ?
According to the charity Action on Hearing Loss, one in six of the general population living in the UK has hearing loss, that is 11 million people. It is believed that this will rise to one in five by 2035, that will be 15.6 million. As we age the prevalence becomes greater, with 40% of over 50s and 71% over the age of 70 living with hearing loss.
World Health Organisation research suggests approximately one-third of persons over 65 years are affected by disabling hearing loss - this is a hearing loss in the better ear of in excess of 40 decibels. This level of loss would be classified as a moderate loss where some one would find it difficult to follow a conversation with two or more people.
What causes hearing loss ?
There are many potential causes of hearing loss, age related hearing loss or presbycusis and noise induced hearing loss been the most common. Both of these causes will result in a sensory neural hearing loss which means the hair cells within the cochlea or inner ear have been irreparably damaged.
Hearing loss can also be conductive in nature which means that sounds are prevented from being processed through the hearing system in a normal manner. This type of loss could be temporary or permanent and may range from a simple blockage in the ear canal such as earwax or it could be something more significant such as a perforated ear drum or related to issues within the ossicular chain - the three tiny bones in the middle ear.
Indication of an undiagnosed conductive hearing loss would normally result in a referral back to your GP for onward referral to ENT as depending on the severity the condition would typically need to be investigated and in some cases could benefit from surgery. Hearing instruments may be required and often individuals with a conductive hearing loss have great success with their devices.
In some cases an individual may have a combination of a conductive and sensory neural hearing loss. This is known as a mixed loss, a typical example would be someone who exhibits a hearing loss constant with age related hearing loss but may also have a perforated eardrum.
There are many other causes of hearing loss, some being related to genetics, ototoxic drugs or even tumours. The first step would be to carry out a hearing assessment.
What does a hearing test involve?
Testing your hearing is not a test of endurance; it should be painless, comfortable and reassuring. If the patient is relaxed the readings will be more accurate.
Before any clinician or audiologist carries out any form of testing they should firstly examine the ear with an otoscope or surgical loupes. This part of the procedure may be carried out with a video otoscope that allows the audiologist and the client to see inside the ear canal. We are carrying out a preliminary health check of the external ear canal at this stage and ensuring any further testing will be valid and accurate.
At this stage in the assessment it is not uncommon to find a full or partial wax blockage in one or both ears. Many clinicians may move to the audiometry phase of the assessment provided they could see the ear drum in the belief that the test will be accurate. Even a slight build up of wax will effect the natural resonance of the patients ear canal potentially influencing the hearing test results at certain frequencies.
If the clinician truly delivers best practice they should remove any wax present using the most appropriate method for the client. It may be necessary to delay and reschedule the audiometry for a few days as the use of microsuction and irrigation can cause a slight but temporary reduction in a patients hearing ability.
In its most basic form a hearing test will mean carrying out pure tone audiometry (PTA) to test the hearing of both ears. It should be noted that assessment of hearing solely using PTA provides only partial pictures of the patient's auditory ability and for the Hearing Healthcare Professional (HHP) to truly understand a clients hearing needs a number of complimentary tests and assessments are available which are discussed later.
A machine called an audiometer is used to produce sounds at various frequencies and the volume or intensity will be adjusted to establish the quietest sound you are capable of hearing.
To undertake a PTA test, the patient may be asked to sit inside a sound booth which will reduce any interference from external noises. Where a sound booth or a sound controlled room is not available such as being tested in temporary test room such as an opticians, health centre or a domiciliary situation there are certain regulations that should be considered. According to the British Society of Audiology where the ambient noise exceeds 35 decibels it is recommended that audiometry should not proceed though this can be higher if the clinician is using insert earphones. Thirty five decibels is equivalent to a soft whisper, there are many smart phone apps that can give you a good indication of levels of ambient noise for your specific situation.
Moving on to the test, you will then be asked to listen to a range of beeps and buzzes through either conventional headphones or insert earphones which are fitted into the ear canal with foam tips. This part of the test is known as air conduction as the beeps and buzzes travel through the air in the ear canal and all three elements of the patient's hearing, the outer, middle and inner ear. The patient will be instructed to press a button to indicate that they have heard them and the clinician can establish the clients threshold of hearing.
The second part of PTA is bone conduction. Unless the air conduction results are returned as within normal thresholds, this will be indicated on your audiogram as no worse than 20 decibels, bone conduction should always be undertaken. A clinician who fails to perform bone conduction is not conforming to minimum standards let alone best practice. The only exception may be if a client is undergoing PTA as part of there six or twelve month routine check.
To perform bone conduction a small block will be placed on the mastoid process - this is the bony prominence of the skull directly behind the ear lobe. A clinician should test a minimum of four different tones but it could be more. As with the air conduction test the patient will be asked to respond to the sound in the manner directed at the start of the test. Often this test may only be carried out in one ear but there are many results that would indicate it should be carried out on both ears. If the clinician deems it necessary to test the second ear this part of the test should include masking. Masking involves the use of a sound played to the ear not been tested to ensure that it is the ear been tested with pure tones is the one to which the patient is responding by pressing the button.
We have been amazed over the years by the number of clients who tell us that they have not had the bone conduction test carried out during previous hearing tests.
Under no circumstances should you let anybody prescribe hearing instruments to you having had a "mini test" through the hearing instruments. Yes they may help you hear better but without PTA performed properly with air and bone conduction the clinician can not be sure if a patient needs to be referred to there GP or onwards to ENT for further investigation.
A clinician operating to best practice would want to be sure they can proceed with the fitting a hearing system in the knowledge that all other options have been properly explored.
Once the PTA is completed, you should move on to Speech testing. It is essential that the HHP understands a clients speech discrimination ability in order to make realistic recommendations and develop a beneficial treatment plan.
Don't be fooled by Hearing Aid Dispensers who mumble ten words from behind a sheet of paper so the client can't lip read, at best this is lazy and unprofessional at worst it is open to abuse by the dispenser by exaggerating the client's perception of their speech discrimination ability in order to secure the sale of a hearing aid.
To correctly undertake a speech discrimination assessment the HHP should be presenting words through the headphones at a decibel level louder than your speech reception threshold which will have being determined from the PTA so you won't have any problem with the volume of the speech. This test uses words of one syllable with vowels and consonants that are distributed similarly to those of words used in ordinary conversations - words such as jar, this, and box. The audiologist asks you to repeat the words you hear. Successfully repeating 90% or more of them is considered excellent.
Although it doesn't mean your hearing is good, a high score on the speech discrimination test is considered good news, it means that you are highly likely to benefit from a hearing aid, as boosting the volume of words will help you understand them better. In other words, your problem is mainly volume, which a hearing aid can help. On the other hand if you only understand a low percentage of the words, simply turning up the volume with a hearing aid is unlikely to help you hear any more clearly.
Speech in noise tests are designed to assess how well a client can hear in the presence of a competing sound such as background chatter in a social situation. Quick SiN is probably the most widely used test of this type routinely used in the UK, it measures a clients Signal to Noise Ratio (SNR) loss. It was developed so an audiologist can quantify a patient’s ability to hear in noise and assist the HHP in choosing an appropriate hearing system with the most suitable features and should they be required, other assistive technologies.
Finally you may be asked to undertake a formal questionnaire. There are a number of questionnaires in regular use, Client Oriented Scale of Improvement (COSI) and Glasgow Hearing Aid Benefit Profile (GHABP) to name but two. COSI s an assessment questionnaire for clinicians to use which allows them to document their client’s goals/needs but just as importantly allows for measurement of the improvement in hearing ability.
The GHABP is a self reported questionnaire that looks at a clients perception of their hearing loss as a disability or handicap prior to use of a hearing system and the clients reported benefit and satisfaction after a predetermined time frame of hearing aid use.
How long should my hearing aids last?
Most manufactures would tell you modern hearing aids last between three and five years. We would suggest instruments to have a lifespan in the region of five to six years. It’s not to say that after this time they will no longer work but the technology will have become obsolete with the release of a number of new platforms during that time. It may well be advantageous to consider the “old” system as a serviceable spare set.
The style or type of hearing aid will be a significant factor on the longevity of the hearing system with in-the-ear hearing aids tending to last around five years though the smallest IIC models being a little less. Receiver in canal and behind-the-ear hearing aids will last longer.
In reality today's technology will last much longer and instruments are capable of being repaired should they fail. What is a factor is the manufactures product cycles, six years may represent three or four product generations which would result in significant improvements in performance. Perhaps the question should really be how often should I upgrade my hearing instruments?
I have been told I have hearing loss in both ears, can I get away with one hearing aid for now?
We make no apologies if this comes across as academically heavy. As a company that believes in evidence based practice we feel that it is important for our clients to understand that we are not just trying to fit them with (or sell them) two hearing aids but there is a scientific basis for our recommendation.
There are countless research papers on this topic. As Hearing Healthcare Professionals, it is our duty to give our clients best advice regardless of a client’s viewpoint or preconceptions. We would want to discover why a client may ask the question in the first place. Is the question driven by the stigma of using hearing instruments or maybe it is financial? A Hearing Healthcare Professional who focuses on their clients best interests and outcomes should examine any objection to the use of two hearing aids where a pair of instruments is clinically the correct solution.
Every week we are asked whether two hearing aids are better than one. If you have hearing loss in both years, then yes, two hearing will always be better but as an evidence based practice let’s take a look at the research that supports this.
A 1999 study by Hurley published in the Journal of the American Academy of Audiology found that a one in four adults with bilateral (both ears) sensorineural hearing loss who receive a monaural (one ear) hearing aid fitting experience a progressive decline in their word recognition score (WRS) in the unaided ear but not in the aided ear. However, only one in sixteen adults with binaural fittings demonstrated a similar deterioration in their WRS.
In a 1987 study, "Long-Term Effects of Monaural, Binaural and No Amplification in Subjects with Bilateral Hearing Loss" published in the Journal of Scandinavian Audiology, Gelfand, Silman & Ross describe how PB (Phonetically Balanced word list) scores decreased significantly only for the unaided ear of the monaurally aided subjects, but not for their aided ear, or for the binaurally aided or unaided groups. These findings suggest an auditory deprivation effect for the unaided ear of those wearing a monaural hearing aid.
Though both of these papers may appear old, they are still relevant and regularly cited in more recent studies.
Two Aids v One Aid
When offered two hearing aids some people may think this means that there hearing must be much worse than someone with only one hearing aid. This is not the case, there are benefits to having two hearing aids, so where possible the audiologist will recommend two hearing aids to achieve the best possible outcome for the client.
Two hearing aids helps to maintain the balance of hearing from left to right, this will help a hearing aid user in a number of ways, such as localising where a sound has come from, better speech intelligibility in noise, and better sound quality through binaural summation - an advantage derived by been able to fit hearing aids with less amplification to achieve the same loudness as one aid on its own.
With one hearing aid, if you have a hearing loss in both ears, you are asking one ear to do the job of two. This puts strain on the ear with the hearing aid, and also deprives the other ear of stimulation.
If you are only offered one hearing aid there may be reasons for this, such as hearing loss in only one ear (unilateral hearing loss), one ear may be unsuitable for a hearing aid in some way. Please speak to you audiologist at this time who will be happy to explain.
Hopefully that explains the clinical basis for being fitted with two hearing instruments but what if the question is driven by financial factors?
Historically in the UK prior to the advent of digital technology it was common for the NHS to fit one hearing aid. Private hearing companies were often charging very high prices and where a dispenser could not sell two hearing aids to a client, their fall back position was to fit a single instrument.
Based on the factors described above a hearing aid user should get more benefit from a pair of instruments of lesser quality than if they were fitted with a single top of the range device. At the time of writing one of our suppliers uniquely offers a technology platform where by a client could be prescribed a pair of entry level instruments and as part of their long term treatment plan the instruments can be upgraded purely by upgrading the hearing instrument software to unlock more advanced functions as a clients financial situation allows.
Do hearing aids need batteries?
As electronic devices hearing aids need some form of power. Historically hearing instruments have used replaceable batteries that would last anywhere between four days and three weeks depending on the size of the battery and the daily use of the hearing instruments.
Siemens Hearing Instruments were one of the first companies to pioneer the use of rechargeable hearing aid battery technology. More recently this type of rechargeable technology called Silver-Zinc has been taken on by a company called Z Power who licensed their system to a number of hearing instrument manufacturers. Both systems utilised replaceable battery cells that were the same size of conventional size 13 or 312 hearing aid batteries. The benefit to this type of technology is that if a user forgot to charge their hearing instruments over night then the rechargeable cells could be replaced with conventional batteries. The down side is that the rechargeable battery cells would typically last twelve to eighteen months before the length of charge decreased or the time taken to reach a full charge increased. Both the above systems are now obsolete and no longer available
With the proliferation of rechargeable consumer devices from cars to mobile phones, there has been an expectation that hearing instruments should also be rechargeable. At Cheshire Hearing Centres we find there is now an expectation from first time users that their hearing aids are also rechargeable.
Of late there has been a move to enclosed rechargeable cells. The challenge to the hearing instrument manufacturers has been, particularly with the advent of streaming sound to hearing aids from an external source that enough charge could be realised whilst maintaining an acceptable charge time and not adversely effecting the size of the hearing instruments.
We are now in a position were we can offer rechargeable hearing instrument solutions in all styles including custom made in the ear models.
Would one of the small invisible hearing aids be suitable for my hearing loss?
The best course of action would be to seek advice from a hearing healthcare professional. We could only answer this once we have an audiogram (hearing test results) but we will need to factor in other requirements such as the size and shape of a clients ear canal and what features they would expect from their hearing system.
I only have a hearing loss in one ear, what can a hearing aid do for me?
Firstly, genuine single sided hearing loss is not normal and should always be investigated.
Many people with the condition take the view that if they can hear well from their "good" ear then they can get by. Those with the condition will often find that they loose track of conversations in groups or social situations as they are unable to hear from there "bad" side. They will struggle with spatial awareness and the ability to identify where a sound or voice has come from. Hearing aids are available for all forms of single sided hearing loss.
Where a client has no cochlea function or severe to profound levels of hearing loss or poor speech discrimination scores on one side, a CROS System can help. CROS is the abbreviation of Contra-lateral Routing Of Signal.
There are two types of available.
A CROS system is intended to help those who are unable to hear in one ear and have normal hearing in the other ear.
A BiCROS system is intended to help Those with little to no hearing in one of their ears, and a hearing loss in their better ear.
To some, the concept can be hard to understand particularly if they have been struggling with monaural hearing for many years. Your HHP should always be willing to demonstrate these systems for you and a suitable trial should be available to help a user truly understand the benefits.