RNID: For deaf and hard of hearing people.

factsheet iconHearing aids factsheet

About this factsheet

This factsheet is part of RNID's hearing aids range. It is written for adults who would like to understand more about loudness recruitment. We use the term deaf people to refer to deaf, deafened and hard of hearing people throughout this factsheet.

Read this factsheet to find out about:

What is loudness recruitment?

If you have a hearing loss you can sometines develop loudness recruitment. Loudness recruitment means you will not be able to hear soft sounds unless they are made louder. However, you may be able to hear loud sounds in the same way that someone with normal hearing can hear them. If these loud sounds are made louder they will be uncomfortable to listen to. This is also described as having a 'reduced dynamic range of hearing'.

Conductive deafness

This is where sound cannot easily pass through the outer or middle ear. This may happen if:

  • hardened wax blocks your ear canal, or
  • your eardrum is damaged, or
  • your middle ear is infected or inflamed; for example, if you have glue ear (see our factsheet on "Glue ear" for more information), or
  • you have a condition called otosclerosis that stops the small bones in your middle ear from vibrating freely (see our factsheet on "Middle ear conditions").

If you have conductive deafness you will find it difficult to hear quiet sounds well and may still have some problems hearing louder sounds comfortably and clearly.

Sensorineural deafness

Loudness recruitment may affect people with sensorineural deafness. This is where the cause of deafness is in the cochlea or in the hearing nerve. Other names for this kind of deafness include 'sensory', 'cochlear', 'neural' and 'inner ear deafness'.

Your deafness is likely to be sensorineural if:

  • you have been deaf from birth, or
  • your hearing was damaged by spending a lot of time in very loud noise, or
  • you have gradually lost your hearing as you have got older

If you have sensorineural deafness you will not be able to hear quiet sounds well and may still have some problems hearing louder sounds comfortably and clearly.

Can someone with normal hearing know what loudness recruitment is like?

Yes. If you have normal hearing you could try listening to orchestral music on a car stereo while driving on a motorway, or on a personal stereo in a very noisy place, such as an underground train. You will probably find that if you turn the stereo up so that you can hear the quiet sections of the music above the background noise, when the orchestra gets loud the sound will be uncomfortable to listen to. This is a similar experience to loudness recruitment. But of course in quiet listening situations you can set the volume at a level where you can hear all the music comfortably. Someone with sensorineural deafness may not be able to do this.

How does loudness recruitment affect hearing aid users?

If your hearing aid amplifies a louder sound, such as a shout, by the same amount as a softer sound, such as a whisper, then you will probably find the louder sounds uncomfortably loud. This means you are likely to turn the volume of your hearing aid down but then you will not be able to hear quiet sounds as well.

Fortunately, all good-quality hearing aids these days are designed to amplify sound levels in a way that allows a wide range of sounds to be heard comfortably. It should not be necessary to keep adjusting the volume control. In fact, some self-adjusting aids do not have a volume control at all.

How can modern hearing aids help?

Automatic gain control (AGC)

Almost all modern hearing aids, whether analogue or digital, have what is known as automatic gain control (AGC). With AGC, when the hearing aid picks up soft sounds it automatically amplifies them more than it amplifies loud ones. This means you can hear the soft sounds but the loud sounds do not become uncomfortably loud.

Hearing aids with AGC may also be called 'compression hearing aids' because they compress the wide range of sound levels coming into the hearing aid into a smaller range of amplified sounds. Your audiologist will be able to adjust the amount of compression to suit you on most compression hearing aids:

  • With too little compression you may still find some sounds uncomfortably loud.
  • With too much compression you may find that everything seems to be at a similar level and you lose the natural loudness differences between distant and near sounds, for example.
  • It is best to have only as much compression as you need in order to avoid uncomfortable loudness.

Multi-band compression

If you have sensorineural deafness you are likely to hear low tones (low frequency sounds) better than high tones (high frequency sounds). You may also tend to have less severe loudness recruitment with low frequency sounds than with high frequencies. To allow for this, many modern hearing aids split sound into several frequency 'bands' and apply compression separately in each band. This is known as 'multi-band compression'. It enables you to make the most of your dynamic range of hearing, even though loudness recruitment has restricted it.

Where can I get further information?

Further information from RNID

If you would like to know more about hearing aids have a look at our leaflet 'The facts: hearing aids' (opens new browser window) and our factsheets 'Buying a hearing aid?' (opens new browser window), 'The NHS hearing aid service' (opens new browser window) and 'Digital hearing aids' (opens new browser window).

RNID Information Line

19-23 Featherstone Street
London, EC1Y 8SL
Telephone 0808 808 0123
Textphone 0808 808 9000
Email informationline@rnid.org.uk