Sound is the oscillation of particles as energy travels through a medium such as air. These oscillations stimulate the ear which sends a signal to the brain and sound is perceived – so it is important to account for the human perception of sound as well as the technical calculation of it.
There are 3 properties of sound we should consider: Frequency, sound level and reverberation time.
We should also consider intelligibility when assessing the acoustics of a space.
Frequency is measured in the number of particle oscillations (cycles) in one second. A healthy ear can hear sounds of very low frequency, 20 Hertz (or 20 cycles per second), to a very high frequency of 20,000 Hertz. Normal speech sound range is about 200 Hertz to 2000 Hertz.
2. Energy in a sound
Energy in a sound wave can be measured using Decibels (dB). The decibel system is frequently misinterpreted as it is based on a logarithmic scale. The increase of 10 dB in sound level corresponds to be perceived twice as loud. Therefore a sound of 80 dB is twice as loud as a sound of 70 dB.
Reverberation is a key characteristic of a room’s acoustic environment. It is created by sound reflecting off the walls, floor and ceiling. When too much sound bounces around a space, speech becomes hard to understand and music loses its clarity. Often quoted as RT60 or T60, it measures the time in seconds that it takes for a sound pressure level to fall by 60dB following an impulse of sound.
4. Speech Intelligibility
Speech Intelligibility refers to how clearly speech can be heard and understood. It is affected by the quality of the speech signal, the type and level of background noise, reverberation and shape of the space. If transmitted also dependent on the properties of the communication system.
While acoustics is an exact science we need to account for the human factor. The Lombard effect or Lombard reflex is the unintentional tendency of speakers to increase their vocal effort when speaking in an environment with high background noise to enhance the audibility of their voice. This change includes not only loudness but also other acoustic features such as pitch, rate, and duration of syllables. Therefore it is important to add sound absorbing elements to an environment to prevent the noise levels escalating.
This is the exercise of stopping sound transmission completely and it is mainly a matter of more structural building acoustics to isolate a space from another. We are not focussing on this aspect at the moment but can indicate firms that do provide such services.
The addition of sound created by special digital generators to reduce distractions and provide confidentiality. The sound spectrum and level is specially shaped to provide the degree of privacy desired by occupants. Masking operates by covering up unwanted sounds. Think of being on an airplane where in a small space the noise level is high but intelligibility of the other passengers’ conversation is very low.
Sound Absorption and Diffusion
Refers to the process by which a material takes in sound energy when sound waves are encountered, as opposed to reflecting it. Part of the absorbed energy is transformed into heat and part is transmitted through the absorbing body. There are a number of very effective solutions to absorb sound within an environment.
Sound absorbing panels and acoustic materials come in different formats to help your space have the ideal reverberation time while minimizing echoes and creating a pleasing acoustic environment.
Wall mounted modular panels Relatively light weight and easy to install these are some of the most commonly used solutions. Should be positioned as close as possible to the source of noise in order to optimise the quantity needed. There are a large number of options in terms of design and colours available.
Hanging panels It can be particularly effective to hang panels from the ceilings especially in spaces with very high ceilings where the vibrations often coming from different sources get lost and limit the intelligibility of speech. A variety of options are available.
Mobile screens Can be an interesting and effective way to divide space in particular in open plan offices between teams or to create areas dedicated to smaller meeting areas or for different functionalities of the space. The mobile factor allows obviously to recreate the spaces according to need.
Writing boards These screens allow for the double functionality of creating sound absorption with the writing board. Particularly interesting to consider for meeting rooms where there is a lot of glass so fitting panels on the walls would be more difficult and the RT is high. These are also available in a variety of colours and can become a feature or blend in the existing colour scheme.
Hanging room dividers There are a number of options of modular screens that can be hung from the ceiling. These allow for dividing and defining a space while letting light and air pass through whilst keeping conversations private. If mounted on railings these can be moved around according to need so to effectively create mobile rooms.
Table screens Classic option for office desks to capture the telephone conversations at source and create defined spaces for employees. Needless to say, this being one of the most used pieces of sound absorbing panels there is a variety of options available and we would highly recommend the use of these in any office!
Wall covering Covering the entire wall these need to be used with caution in order to not create too much sound absorption at once. The products we have researched and selected are available at varied sound absorption classes so to be usable for the entirety of the wall space. We have a number of fun options from wood to crocodile to vertical gardens for the wow factor!
Ceilings It would be great to always have some absorbing materials on the ceilings and there are some good solutions that are effective and a neat way of fixing acoustic issues in an environment. They can be basic suspended ceiling tiles to be substituted to the existing ones, baffles when light should be passed through or even stretch ceilings for non-linear spaces.
Lighting A number of the other acoustic products may be integrated with lighting and there are also a number of lights that are integrated with sound absorbing materials that can be interesting to integrate in fixing the acoustics of a space.
Curtains In general most textiles present light sound absorbing or at least sound diffusing qualities but there are a few curtains that have been developed with high sound absorbing characteristics that can be tailor made to any window and in addition to aiding the acoustic quality of a space can also save on energy bills.