Hearing access specialists
Hearing access specialists

Illustration of people talking with a bus passing behind them

Good acoustics and reduced background noise make all the difference to the way you hear, especially if you are listening to speech.

The process of hearing, listening and understanding is sophisticated and involves the physical properties of the ear and a complex series of interactions in our brain.

Something called ‘auditory processing’ must occur, which means that your brain recognises and interprets the sounds heard so that it becomes meaningful information.

For those with a full hearing range, auditory processing is typically done subconsciously and easily. It is done with the same ease with which most people breath.

For those with hearing loss or another condition that make processing of sound difficult, hearnig and listening take effort and thought. In an environment where there is background noise or poor acoustics then it becomes much harder still.

How we hear

Sound is made when objects vibrate and it travels in waves, spreading outwards from the source of sound. It varies in loudness (intensity) and pitch (frequency).

Loudness (intensity) is measured in decibels (dB). Frequency (pitch) is measured in Hertz (Hz). All sounds are made up of different frequencies.

The three main elements that affect acoustics are:

  1.   Noise levels 
  2.   Echo or reverberation
  3.   Sound insulation

1.  Noise levels

Sources of noise that can affect acoustics include:

  • road, rail and air traffic
  • people outside or in adjacent rooms
  • nearby industrial or commercial activity
  • building services, such as ventilation systems
  • equipment like computers, overhead projectors, machine tools
  • rain noise on lightweight roofs

2.  Reverberation

Reverberation is the collection of reflected sounds from the surfaces of an enclosed space. It makes the sound persist after it has been produced. It mainly comes from low frequency sounds.

Speech includes lots of low frequency sounds. These are mainly the vowels – and they tend to sound louder when we say them than the consonants e.g. fish, cow, hut.

Consonants tend to be high frequency sounds. They give clarity to speech. If you cannot hear them then words are difficult to understand.

Echo or reverberation means louder low frequency sounds bounce around the room.  This blurs words and makes it more difficult for people to understand speech.

3.  Sound insulation

Reverberation varies depending on the size, shape and nature of the room.  Sound insulation reduces the amount of low frequency sound bouncing around and makes a space more hearing-friendly.

Sound insulation can be created by carpets, soft furnishings, table cloths, soft seating, noise absorbent panels and other treatments.

Difficulties in hearing are created by high ceilings, hard surfaces and noise from adjacent rooms, conversational chatter, music and other ambient sounds.

Signal-to-Noise ratio

People with a full hearing range need to have the speaker’s voice (the ‘Signal’) 6 dB louder than the background noise (Noise) in order to make sense of what’s being said. This is a Signal to Noise (S/N) ratio of + 6dB.

For someone with hearing loss, this needs to be +16dB or more. Studies have shown that the more favourable the S/N ratio, the easier it is to understand what is being said.

Illustration showing sound moving from a speaker to the listeners

Hearing aids, noise & acoustics

Hearing aids are fantastic technological devices and there have been great leaps in recent years in how they can assist in different listening environments.

However, background noise and poor acoustics remain a challenge because hearing aids amplify both wanted and unwanted sound.  They also amplify any distortion, such as that caused by reverberation.

No matter how sophisticated the hearing aid, it will struggle in poor listening conditions. No hearing aid can fully mimic natural hearing.


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