Top questions about acoustics, sound quality and noise

In this article, our Global Acoustics Ambassador Pascal van Dort answers some of the most frequently asked questions surrounding acoustic design.
In order to understand a room’s acoustics, it’s important to first find out how sound travels. So, silence the noise in your mind, sit back, relax and discover how to improve your room’s acoustic performance.

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How does sound travel in a room? 

Sound waves are mechanical vibrations that are transmitted through a medium such as air and water. They are reflected, absorbed, transmitted and diffused.  

Why do you think singing in the shower sounds better than singing in your bedroom? In your bathroom, you have either hard or smooth surfaces that reflect sound waves. On the other hand, in your bedroom, there are a lot of soft materials, such as your bed, which absorb sound.  

In offices, all different kind of materials, constructions and finishes, such as walls, suspended ceilings and flooring absorb or reflect sound. Additionally, desks, office cabinets, and plants are all good at diffusing sound. 

Look around - how sound is the room you’re currently in? You might need to improve the acoustic design of this space. If so, you’ll need to understand the role of acoustics before you begin. 

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Why are acoustics important? 

Let’s start by defining acoustics: ‘the quality of the room that determines the audibility and the fidelity of the sound in the room’. The level of architectural (room and building) acoustics can have a huge impact on your overall health and wellbeing. 

Bad acoustics in hospitals increase patients’ blood pressure and heart rate [1] (Hagerman et al., 2005). In education, good room acoustics improves students’ levels of attention, performance and understanding, and it lessens the fatigue of the teachers’ voices [2] (Castro-Martínez J.A. et al., 2016).

In a survey conducted by the Leesman Index, 76% of office workers list noise as a crucial workplace consideration, with a catastrophic average satisfaction score of just 30% [3] (Leesman Index, 2019). By creating a workplace environment with good acoustics and reducing distracting sound elements, a number of benefits can be observed in the office [4] (Sykes, D M., 2004): 

  • 48% increase in employee focus 
  • 51% drop in employee distraction 
  • 10% fewer errors made 
  • 27% reduction in stress level 

Although we are all affected by noise, we often pay little attention to it. But by taking acoustics into account at the beginning of the design process, we can minimise the presence of a bad acoustic indoor environment. Sounds perfect, right? 

What does it mean when a room has good acoustics? 

The acoustic of a room depends on what is the purpose of that room, and how it’s being used. A church, which is normally very reverberant, has excellent acoustics for playing the organ. But a vicar may feel that he or she is not being understood clearly when giving a sermon. Reverberance and background noise both influence a room’s acoustics. 

Good acoustics means that sound retains its beauty and clarity. For example, if there's a lot of noise from a ventilation unit in a classroom, the teacher will find it harder to deliver the lesson. 

How do acoustics affect sound quality? 

Have you heard the sound of the beats in an orchestra? The reflections, absorption and diffusion in concert halls are designed to enrich the sound of music the orchestra is playing. The acoustics in a room can hugely improve sound quality. A lot of acoustic parameters determine the sound quality of a room:     

  • Reverberation Time (T30): reverberance (sec.) 
  • Early Decay Time (EDT): first sound reflections (sec.) 
  • Clarity (C80): perceived clarity of music (dB) 
  • Speech Transmission Index (STI): clarity of speech 
  • Sound Strength (G): perceived sound level (dB) 

The next time you are in an auditorium, rehearsal space, meditation room or media room, pay attention to the different sounds and the effect they have on you. 

Which materials can be used to absorb sound? 

The technology for improving sound quality has changed in the past decades. Sound-absorbing materials can be divided into three categories: porous, membrane and resonators. Porous, soft and light materials such as mineral wool (stone wool), natural fibres or foam are commonly used to absorb sound. 

Absorbing properties can be described by a weighted sound absorption coefficient (αw). The coefficient can be viewed as a percentage, where 0.01 is minimal (1%) and 1.00 is complete absorption (100%). 

In order to achieve great acoustics and make people feel better in their given environment, different solutions can be applied and installed. At Rockfon, we’re the world’s leading acoustic company and our mission is to keep things quiet. Our large variety of noise-absorbing solutions can turn noisy spaces into comfortable spaces with a big impact.  

All so that humans can create, focus and thrive. Sounds beautiful right? 

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References

[1] Hagerman, I., Rasmanis, G., Blomkvist, V., Ulrich, R., Eriksen, C. A., & Theorell, T. (2005). Influence of intensive coronary care acoustics on the quality of care and physiological state of patients. International Journal of Cardiology, 98(2), 267–270

[2] Castro-Martínez J.A., Chavarría Roa J., Parra Benítez A., González G. (2016). Effects of classroom-acoustic change on the attention level of university students. Centro Interamericano de Investigaciones Psicológicas y Ciencias Afines. Interdisciplinaria, vol. 33, no. 2,

[3] Leesman Index (2019): The Workplace Experience Revolution Part 2, Second digital edition.

[4] Sykes, David M., PhD., 2004, “Productivity: How Acoustics Affect Workers’ Performance in Open Areas”