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The basics of understanding acoustics

April 13th 2023
The basics of understanding acoustics

Silence is Golden is a proverb thought to have dated back to Ancient Egypt and whilst acoustic products can't make spaces totally silent, they are able to provide noise reduction for internal work, social and hospitality spaces.  

Many of us have had to adapt to new working environments over the past few years and acoustics has now become a key factor to our performance and well-being. A well-balanced room with spot-on acoustic levels is a key factor in the performance and well-being of people all over the world.

When we think about treating sound within a room, we need to start by understanding the basic terminology of acoustics. And, like a lot of things, better acoustic performance starts with a solid foundation on which to build.

Read on to discover the basics of understanding acoustics:

Definition of sound - sound consists of pressure waves running through the air. It is usually described as energy, created by vibrations, transmitted through air. It’s energy, created by vibrations transmitted through air or any other medium. Our inner ear converts those vibrations into electric signals, which are sent to our brain, where they will be processed and perceived as the actual sound coming in.

Sound waves have two different characteristics:

The frequency which determines the tone of the sound and the decibel determines the intensity of the sound.

Frequency and how sound waves travel:

The wavelength determines the sound frequency. It is measured as the number of repetitive vibrations per cycle per second and is expressed in Hertz (Hz). The audible range of sound ranges from 20 to 20 000 Hz. The higher the frequency, the higher the tone. It’s interesting to note that for internal space planning, the recommended frequency ranges from 100 Hz to 5000 Hz.

High tones

High frequency | Short wave | 2500 - 12000 Hz | e.g. ringtones

Mid tones

Speech frequency | Mid length wave | 250 - 2500 Hz | e.g. speech

Low tones

Low frequency | Long wave | 50 - 250 Hz | e.g. air conditioning

The intensity of sound

Decibel is a logarithmic unit to express the ratio of sound intensity (volume) and is important as an indicator of the background noise level. Humans can hear sounds between 0 and 140 decibels. The value of decibels has no direct or indirect correlation with the sound frequency.

For example, the ticking of a clock and the sound of a boiling kettle may have the same frequency but a different volume.

Does it matter? 

In today’s open-plan workspaces, people are usually exposed to noise pollution. The level of noise ranges from 60 to 80 decibels. The recommended background noise level in the workplace is around 45 dB. It should go without saying that noisy workplaces will affect concentration and interfere with collaboration. Acoustic pods and acoustic booths are a great solution to create mini environments or rooms within rooms that can be designed with sound balance in mind and so yes it does matter!

Reverberation time

Reverberation time is the time needed for sound to drop dead, is an original sound source to decay 60 dB and is expressed in seconds. In order to hear each other properly, the reverberation time should be adjusted and balanced by means of absorptive material, such as acoustic wall tiles, acoustic plants and acoustic screens. The reverberation time will always be influenced by the volume of the room, temperature and existing absorptive materials such as objects, materials and people.

Recommended reverberation times for different spaces are as follows.  Offices 0.75s, meeting rooms 0.60s, cafeteria 1.00s and gyms 1.50s. In an office, high reverberation intensifies the existing distracting sounds, as the sound reflects from walls and office desks, among other hard surfaces. Reverberation can cause difficulties to understand your conversations with colleagues and distractions due to people speaking at either end of large spaces.

Room acoustics v building acoustics

Room acoustics and building acoustics may sound like the same thing, but that isn’t the case. There is a clear distinction. The solutions to treating acoustic problems associated with either are very different. Building acoustics is to do with the building and the transmission of sound from the outside to the inside and between structural elements of a building such as walls and floors. External sound travels from cars, trains, and airplanes passing by. Sound is also transferred between floors and between adjacent rooms such as adjacent meeting rooms.

Sound travel should be addressed by Architects through the insulation of windows, walls, ceilings, and floors. However, if your interior is acoustically unsound, another option is to install acoustic products to prevent sound from escaping from spaces.

The key to room acoustics is absorption by installing acoustic products to prevent sound waves from bouncing back and forth from hard surfaces in a room.

How to create better room acoustics

To create a better acoustical environment and reduce reverberation time in an internal space, take a look at our acoustic solutions category. This category has been developed with products that address sound absorption, attenuation, and diffusion issues.

Absorption - Sound waves are absorbed by any acoustic soft material they touch.

Attenuation - Reducing the sound transfer within a room.

Diffusion - Sound energy is spread evenly in a given space.

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