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 eardrum in the belief that the test will be accurate. Even a slight build up of wax will affect the natural resonance of the patient's 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 complementary tests and assessments are available which are discussed later.
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.
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 smartphone 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.
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.
