How to solve a problem like acoustics

Hearing, yes hearing, hello, hello, yes I said hearing, can you hear me now?

Croft Architecture Building AccousticsJokes aside, the ability to hear is such an important sense along with sight. Our ability to hear with ease and clarity is something we may take granted on a daily basis. We do it without even thinking about it.

Without sound wouldn’t the world be a different place?

No Sound causes confusion Croft ArchitectureSocialising, working, interacting and even relaxing would be a completely different experience in comparison to a world full of sound. Sound and our ability to hear provides us with such an enormous source of information. Good hearing keeps us safe and alerts us potential dangers in our environment.

To lose our ability to hear from such a world rich in sound would not only make life extremely difficult and potentially dangerous, but also make us feel extremely isolated. The sounds we hear allow us to make decisions, communicate and react accordingly. A world without sound or clarity of sound would become a very lonely environment.

Now we have reflected about the importance sound we can truly be in ore of the human body and our sense of hearing.


Sound: it enriches our lives and helps us to participate in life more fully without limitations...Or does it?

Back in the 6th century BC the Greek philosopher Pythagoras found some limitations to sound and its quality. He discovered that some musical sounds were more beautiful than others. His study of music was the beginning of understanding acoustics and the nature of sound.

The limitations of sound were discovered from the understanding of how it travels. Aristotle’s research found that sound travels in waves with a fluid movement of expansion and contraction.

Sound Waves Croft Architecture

Over time further investigations were made. Roman architect Vitruvius studied the acoustic properties of Roman theatres considering interference, echoes and reverberation. His work was the beginning of architectural acoustics.

As centuries passed the pace of discovery and understanding gathered momentum, with great researchers such as Galileo discovering pitch and that sound travels in waves produced by vibrations.

Now, it's time to take your toga off and put your 21st century head back on.

Today we live in an age with such an in depth knowledge of sound. Our ability to understand sound and its properties means we can control sound and the noises we experience within a building.

Where sound is of great importance to achieve intelligible speech, the architectural acoustics require careful consideration to make the environment a success.

Buildings that require design to enhance speech intelligibility are;

  • Theatres & Concert halls - designed with ascending seats to prevent deterioration of sound,
  • Railway stations,
  • Recording studios,
  • Offices,
  • Educational institutions

Concert Hall Accoustics Croft Architecture

Maciej Bledowski /

Accoustics in the classroomSpeech Intelligibility Croft Architecture

Take yourself back to your school days and place yourself in the sports hall in a PE lesson.

How often did you have PE where you were unable to hear the PE teacher’s instructions?

Was the teacher shouting to be heard, but failing to instruct due to the reverberation of their voice?

Or were they talking so quietly to prevent reverberation, only not to be heard as a result of their low volume?

What is speech intelligibility? 

Effective teaching Croft ArchitectureThe crucial part of any lesson is the signal to noise ratio. This refers to speech intelligibility and how understandable speech is in a room. The way in which the intelligibility of a space is measured is the ratio of the background noise level in dB subtracted from the sound level of the teacher’s voice in dB.

The higher the difference in ratio the better the intelligibility of the teacher’s voice. If the background noise is louder than the teacher’s voice their speech will be harder to understand.

Sound reflections from hard surfaces that are far apart like the walls in a school sports hall, arrive at the listener differently. Our brain then interprets this sounds as an echo, thus impacting upon the quality speech intelligibility.

In the classroom if there is too much absorption from the rear walls this will reduce the energy of the teacher’s voice. Sound diffusing materials can be used to help transfer the sound so the teacher’s voice remains intelligible wherever the pupil is sitting.

High noise levels in schools and poor architectural acoustics will only lead to poor speech intelligibly. If the teacher cannot be heard children will lose concentration and interest, subsequently leading to lower academic performance and increased stress in both teachers and children.

Since 2003 the Government has updated Building Regulations. They require the design and construction of all academic institutions to provide a teaching environment that meets the acoustic requirements to enable effective teaching and learning.

Building Regulations Requirement E4 states that:

“Each room or other space in a school building shall be designed and constructed in such a way that it has the acoustic conditions and the insulation against disturbance by noise appropriate to its normal use”.

The aim of the regulations is to provide suitable indoor ambient noise levels for teachers, pupils and pupils with special needs, including hearing impaired pupils, and those with speech, language or communication (SLC) difficulties.

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The transmission of noise from the building’s exterior envelope to the inside will travel through noise paths such as the;

  • roofs,
  • eaves,
  • ceilings,
  • walls,
  • windows,
  • doors.

The solutions

Architectural Accoustic Foam Croft Architecture

Limiting or controlling the noise from the sounds paths is the solution but it will depend on the source of noise and the path taken. Controlling sound within a buildings interior with sound absorbing or reflecting materials will help with noise interference and also the signal noise ratio.

The design of each space requires careful thought in relation to the rooms purpose. Only then can appropriate materials and designs be considered to enable intelligibility and reduce interference.

Whatever the learning environment children need to be able to hear the teacher to maintain concentration with little effort. The space must allow easy two way communication between teachers and pupils without loss of intelligibility so information can be accurately registered.


Architectural acoustics should make the teaching environment a productive and a pleasant place to learn.


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