audiometry

Speech audiometry


After completing pure tone audiometry you may proceed with speech audiometry. You would not perform speech audiometry for every client you see. It is rare to include speech audiometry in a screening test. If the client comes from a non-English speaking background it may not be appropriate to perform speech audiometry.

When carrying out speech audiometry the speech may be presented live voice or by using a recording. A live voice test is a speech test where the clinician presents the speech stimuli through the microphone of the audiometer. Recorded speech tests are available on audio cassette or CD. There are some recorded speech tests materials available using different varieties of English speakers and if you have a choice you should use the variety used by the client. That is, recordings using Australian speakers are preferable for Australian clients than recordings made using other accents.

There are advantages and disadvantages in both kinds of presentations. Live voice tests can be conducted using any speech test material, and therefore, there is a great deal of flexibility. However, they cannot be used to compare results on one day to another or from one clinician to another. It is very difficult for the clinician to maintain the level of presentation with absolute accuracy when presenting live voice but this is obviously no problem with a recording.

Speech audiometry can be presented monaurally or binaurally i.e., to one ear or both ears.

Many clinicians feel that speech has greater applicability in determining the effect of a hearing impairment, as communication through speech is the major function of hearing. It is possible for two clients to have the same audiogram but have very different abilities to use the information they receive. If you determine handicap by the pure tone audiogram both would have the same degree of disability.

The difficulty with using this approach is that there are many variables that affect the ability of an individual in a speech test. These include the experience, education and culture of the client. If the client is unfamiliar with the speech material used then they will not score as well.

In comparison, the variables in pure tone audiometry can be controlled so one person’s audiogram can be directly compared to another’s.

Speech Audiometry is used for a variety of reasons. It may be used:
1. To check the validity of pure tone audiometry.
2. To determine speech discrimination.
3. To establish rehabilitation needs.
4. Diagnostically.

Checking the validity of the pure tone audiogram

There is a strong relationship between the 3FAHL and the SRT and therefore can be used to check if the client is giving reliable responses The SRT is the Speech Reception Threshold. The SRT is the intensity at which simple speech material, usually spondees, can be detected 50% of the time.

Spondees are word with two syllables that have equal stress on each of the syllables, e.g., fruitcake, meatball, childcare etc. The spondees are usually presented live voice.

Determining speech discrimination

When there is a hearing loss there is a breakdown in the hearing mechanism. When the client has a conductive loss it is usual that they are still able to discriminate speech very well but they need extra volume to do so. That is, the breakdown affects how loudly speech is heard but not how clearly. However, when the client has a sensorineural hearing loss, the clarity of speech is affected so that no matter how loud the speech is heard it will still not be clear.

To determine how well a client can discriminate speech, speech discrimination tests are performed at the level that will produce the best results.

The intensity level at which maximum speech discrimination will occur is not easy to predict. The rule of thumb is that the intensity level at which speech is best discriminated is usually 30 - 40dB above 3FAHL.

Speaking to the client through the earphones will help to establish the level at which the client will hear speech best. This level is usually about 10dB above the most comfortable level (MCL).

There is no one speech test that is used by all clinicians to determine speech discrimination. Most clinicians will use monosyllables, i.e. single syllable words. There are lists of words that have been devised for this purpose.

Some clinicians prefer to use a number of short lists to compare scores across a range of intensity levels.

This will provide the clinician with a better understanding of the client’s abilities and disability.

Many clients will expect an amplification device to solve their communication difficulties. There is no hearing aid that will repair the damage that caused the hearing loss. If the client has poor speech discrimination their expectations may be unrealistic. Knowing the client’s ability to discriminate speech will assist the clinician to explain to the client the benefits that can be realistically expected from an amplification device.

Establishing rehabilitation needs

The aim in rehabilitation of clients with a hearing impairment is to reduce their communication difficulties. The majority of clients with a hearing impairment will hope to improve their ability to understand speech. Therefore, speech tests are used to determine the types of problems experienced.

Many clients experience difficulties in background noise. It is possible to perform speech tests in noise but there is no standard procedure used across Australia. There are tests available if you want to do this.

If you want to demonstrate tactics or show the benefit of an amplification device you can use a radio for background noise or use a recording of ‘cocktail party noise’.

Speech tests may also assist in determining the level at which the client experiences discomfort. The uncomfortable loudness (UCL) level should be kept in mind when selecting an amplification device.

Diagnostically

Speech tests are often used to determine the site of lesion of the hearing impairment. Speech tests are particularly effective in diagnosing central impairments.

A performance intensity (PI) function can be plotted for diagnostic reasons. The discrimination score achieved at a number of different intensity levels are plotted on a graph. If the speech discrimination reaches a maximum point and then gets worse as the intensity is increased this shows rollover. If rollover is observed the client must be referred to a doctor or an audiologist for full diagnostic audiometric assessment.

NB: Recording the intensity level of speech.
Speech is a broad band signal and is often recorded in dBSPL. Audiometers vary in the relationship between the intensity displayed and the level of speech. You will need to check the manual for your audiometer to know what this relationship is. Many audiometers have a 20dB correction. That is, at 0dB on the audiometer the speech is presented at 20dBSPL. You must write the correct level on your file. However, you must check with the clinic you are working in as to the procedures followed.

Conveying results to clients

All clients are entitled to understand the results of their audiometric assessment. They must be able to understand what you are telling them so you should avoid the use of specialised words, jargon, that won’t mean anything to the client.

Most clinicians prefer to explain their own results but this depends on where you work and the purpose of the hearing test. For example, if you work for a doctor they may prefer to explain the results themselves. If nothing else you should at least give the client an encouraging comment like: ‘You did that test really well. The doctor will explain the results to you’.

Many clients ask what percentage hearing loss they have. Percentages are relevant in workers compensation but do not convey much meaning. What would it mean to you if I said you had a 10% hearing loss?

It is more meaningful to describe hearing loss in terms of the types of hearing problems a client will have and relate the results to the history. At the end of the explanation of the results you should tell the client what action needs to be taken. For example, to a client with a mild-moderate, high frequency sensorineural hearing loss that is the same in both ears. The client has already seen an Ear Nose and Throat Specialist who has said there is no medical treatment and the otoscopy was clear. During the history the client told you they are seeking your advice about hearing aids.
‘This is the chart of your hearing. We call it an audiogram. Across the top of the audiogram is the frequency of the sounds you were listening to. The low pitch ones are on this side and the high pitch ones are on this side. This isn’t the full range of human hearing but these are the most important frequencies for understanding speech. The full range goes from 20 cycles per second or Hertz up to 20,000 cycles per second.

Down the side of the audiogram is how loud the sounds have to be for you to just hear them. The further down the page the louder the sounds had to be.

The circles are your right ear and the crosses are your left and you can see they are about the same. This half box is called bone conduction. That was that vibrator that was sitting behind your ear. The bone conduction results tells us where the hearing problem is. The results are about the same as the others so we know that there is nothing in your ear canal or in your middle ear causing the hearing problem. This means that the doctor can’t fix your hearing. Your problem is called a sensorineural hearing loss which means there is some damage in the inner ear.

If your hearing was in the normal range all the circles and crosses would be above the line at 25dB. Your hearing is fairly close to normal in the low frequencies but gets worse in the higher frequencies. The low frequencies give us a lot of the volume for speech but the high frequencies give us a lot of information for the clarity of speech. So you can hear that someone is speaking but you can’t always make out what they are saying. Especially when you’re at the club and there’s a lot of noise or you can’t see the person’s face.

Hearing aids would definitely help you.’

This is just one way of explaining results to clients. It is not suitable for every client. Some clients do not need as much explanation and some need more.

Clients do not remember everything you say to them so giving written explanations is helpful. You can prepare general information beforehand and highlight relevant parts. Information giving is an ongoing process and you should be prepared to answer client’s questions at any time.

You may also recommend that clients get more information from self help groups. These groups often have information brochures to help people understand hearing loss.

Referring clients

An audiometrist cannot refer clients in a medical sense. When we talk about referral in audiometry we are simply talking about asking the client to see someone else.

There are many people who work with the audiometrist. These include:
• Audiologists
• the General Practitioner - GP
• the Ear Nose and Throat Specialist (ENT)
• Paediatricians
• Neurosurgeons
• Teachers
• Occupational Health and Safety Practitioners
• Rehabilitation Counsellors
• Occupational Therapists
• Speech Pathologists
• Self help Groups.

The majority of clients will have been asked to see you for an assessment for a variety of reasons that can be classified as follows:
• Medical
• Rehabilitation
• Educational.

You will ask clients to see others for a variety of reasons.


YOU ARE ASKED TO SEE THE CLIENT TO:

YOU ASK THE CLIENT TO SEE ANOTHER BECAUSE:
determine degree and type of loss prior to or after medical intervention
there is a conductive loss or asymmetry *
determine degree and type of loss because the client complains of hearing loss
the client complains of medical symptoms, e.g., dizziness, tinnitus pain, discharge, fluctuating hearing loss *
monitor the effects of a noisy working environment
the client experiences difficulties in their working life
determine reasons for communication difficulties
the client experiences educational difficulties
assess clients at high risk for hearing impairment
the client experiences speech difficulties greater than would be expected from the audiogram
assess the need for amplification or other device/s
they would benefit from the support of a self help group

*Ask the client to see their GP, possibly for ENT or other specialist referral. If you feel a client should see a specialist medical practitioner you can only suggest this to the GP. The GP then arranges for a referral if they believe this is the best action to take.

Any time you are uncertain about the hearing results you should consider asking the client to see someone else. At this stage of your training, all results should be discussed with your supervisor and you should ask your supervisor for direct assistance when you suspect the client is not responding as well as they should, when there is asymmetry and when there is an atypical audiogram.

Monitoring referral

It is easy to lose track of clients who you have asked to see someone else. If you wish to see the client again or if you wish to know what happened you will need to monitor the referral. You may find your clinic has certain methods for this or you could simply write in your diary e.g., select an appropriate length of time and write ‘Review Mr/Ms_ _ _ _ _’

Writing reports

Reports are written for many reasons. The reason the report is written will affect how it is written. You should adjust how you write the report to suit the person who is to receive the report.

Reports should include:
a) an opening statement as to why the client was seen, e.g., ‘Thank you for referring Mrs Y.’ ‘Mrs Y arranged an assessment as she has been experiencing increasing difficulty with her hearing.’
b) a description of the audiogram including type and degree of loss, e.g., ‘Pure tone audiometry shows a bilateral, symmetrical, mild-moderate sensorineural hearing loss.’ or keep it simple, ‘Hearing test shows a mild-moderate sensorineural loss in both ears’. It is difficult to keep a report completely simple but most people working with the hearing impaired will know the basic terminology.
c) a statement about what action was decided on, e.g., ‘Mrs Y has decided to trial a hearing aid in the left ear.’ ‘I have asked Mrs Y to see you as she would like to talk to you about medical options before proceeding with a hearing aid.’
d) a concluding statement, e.g., ‘If you require any further information please contact me. I am available on 02 9777 7777 on Mondays and Wednesdays.’

Reports can be handwritten but if nobody can read them they are useless. Many clinics have printed report forms or templates on computer.

You should always keep a copy of the correspondence you send and make a note of the people they were sent to.

The more practice you get writing reports, the better you will be. One useful practice is to keep samples of good report writing.