What is sound?
Sound can be described as energy that is transmitted through vibrations in the air or any other medium. The inner ear transforms this energy into electrical signals that our brain processes and perceives as sound.
Sound waves have two basic characteristics:
- Frequency, which determines the pitch of a sound.
- Intensity, expressed in decibels.
Frequency: How do sound waves travel?
The wavelength determines the frequency of sound, measured in cycles per second and expressed in Hertz (Hz).
The audible spectrum for the human ear is in the range of 20 to 20,000 Hz. The higher the value, the sharper the sound. In the context of room treatment, the typical range treated is between 100 and 5,000 Hz.
High frequencies – Short wavelength – 2,500-12,000 Hz (example: a telephone ringtone).
Speech Frequency – Medium Wavelength – 250-2500Hz (e.g., human speech)
Low Frequencies – Long Wavelength – 50-250Hz (e.g., ventilation systems)
The intensity or volume of sound is expressed using decibels, a widely used logarithmic unit to indicate the level of ambient noise. The human ear has a tolerance of up to 140 decibels, which is the threshold of pain.
The decibel value has nothing to do with the frequency of a sound. For example, the singing of a bird and the hum of a fan could have the same frequency but at different volumes.
Why is it important?
In today’s open-layout workspaces, employees are exposed to auditory stimuli that can be annoying. Typically, these noises fall in the range of 60-80 dB, while the recommended ambient noise level is around 45 dB.
It’s easy to imagine that too much noise directly affects employees’ concentration and productivity and interferes with communication among them.
There are several ways to prevent the stress associated with the inability to concentrate, from acoustic booths to creating microenvironments with dividers, to treating surfaces with acoustic panels.
Reverberation time, expressed in seconds, is the time it takes for a sound to decay by 60dB. Complete suppression of reverberation is generally not desirable since the reverberation time should be adjusted, through acoustic absorption materials, to the specific issues of a given space. Thus, RT will always be influenced by the volume of the space and the absorbing materials already present in it (materials, objects, people, etc.).
As a guideline, the reverberation time in an office should not exceed 0.75 seconds, while in an auditorium, values between 1.5 and 2 seconds are acceptable.
Why is it important?
In a workspace, excessively high reverberation times intensify and worsen annoying sounds, as they are repeatedly reflected off walls, tables, and other hard surfaces. This leads to difficulties in maintaining conversations with colleagues, as well as distractions caused by other conversations in the same space.
The way to mitigate these issues and reduce reverberation is through the use of absorption materials.