Acoustics

Why is good acoustics important?

Silent space is perceived pleasant. There is no need to raise one´s voice in order to be heard. Productivity is better because attention is maintained and concentration is easier. A better physical and psychological health supported by silence is good for everyone, including the workers and the employers.

Noise is a disturbing sound. According to WHO, noise is harmful to health and affects people’s daily activities at school, at work, at home, and in leisure time. Noise can interfere with sleep, induce cardiovascular and psychophysical symptoms, and reduce performance, cause irritation and cause changes in social behavior. The average noise level should not exceed 35dB during the day. Echo increases noise level.

A 2014 study by Steelcase and Ipsos found that workers lost as much as 86 minutes per day due to noise distractions.

When young children are regularly exposed to levels of noise that interfere with speech, they may develop speech or reading difficulties, because auditory processing functions are compromised. Evidence has shown that when children learn in noisier classrooms, they have more difficulties understanding speech than those who learn in quieter settings. A study published by Cambridge University Press in 2011 found that chronic noise exposure is associated with impaired reading comprehension and high levels of noise annoyance with school children.

How much acoustic products are needed?

The echo is generated when the sound waves are reflected from the walls and they are only suppressed when sound waves meet the dampening surface. The larger the space and the harder the surfaces, the longer is the reverberation time. Acoustic phenomena are physical and can be measured and calculated by simplifying followingly:

If the volume of the room is 100 m3 and if there is 16 m2 of absolute absorption material in it, the achieved reverberation time of the room is 1.0 s. The length of the echo is halfed by doubling the amount of the absorbing material. If the size of the room is doubled, the amount of absorbing material needs to be doubled to keep the same echo.

The reverberation time of a room can be measured or the amount of absolute absorption material can be estimated based on the room surfaces and materials. The usage of the room defines the targeted reverberation time. Good reverberation goals are following:

  • office and children’s playgroud 0,4…0,6 s
  • video or voice conference room, phone booths less than 0,45 s
  • home theatres 0,3…0,4 s
  • living rooms of the senior houses 0,5 s
  • livingrooms 0,5…0,8 s
  • speech halls less than 1,0 s

Yeseco offers services for estimating the absorption material need.

How to compare absorption capabilities of different materials?

There are big differences in the performance of acoustic products. Thin and hard materials, such as textiles and furniture, absorb a bit of sound, but only a good acoustics product attenuates the sound efficiently.

Yeseco products are acoustically effective. No airgap is needed behind them. They are measured at VTT (Finnish National Test Laboratory) according to EN ISO 3565 / EN ISO 11654 standards. All our wall acoustics are of the best sound attenuation class A, and Still T reaches the best in class weighted sound absorption coefficient aw 1,0 which implies best possible 100% sound absorption in the class.

How to compare different sound absorption coefficients aw?

Many products require an air gap behind them to improve the sound absorption at the lower frequencies and to match the absorption with the spectrum of the human voice.

When the declared total height of the installation is the same as the thickness of the product, the sound absorption coefficients aw can be directly compared with the sound absorption coefficients of the Yeseco products.

How to reach the same sound absorption with different products?

In order to get the same results, the total absorption of the different materials must be equal. The comparison is made through the residual sound after absorption.

For example, if the sound absorption coefficient aw is 0.97, i.e. sound attenuation is 97%, the residual sound is 3%.

If the sound absorption coefficient aw is 0.80, i.e. sound attenuation is 80%, the residual sound is 20%. After attenuating this again by 80% the new residual sound is 4%. In other words, aw 0.80 material is needed more than 2 times the amount of aw 0.97 material.

The following table describes the difference in the amount relative to the 97% attenuating product:

95% 1,17
90% 1,52
85% 1,85
80% 2,18
70% 2,91
60% 3,83
50% 5,06
30% 9,83
20% 15,71
10% 33,28
5% 68,36

When acoustic material is purchased to eliminate any acoustics problem, it is worth choosing effective Yeseco acoustics product. Then, the desired sound attenuation is achieved cost-effectively. No air gap structures are needed, the required amount of acoustic material is smaller leaving room for interior design options.

Where to place the acoustic panels?

Acoustics improve when sound-absorbing material is placed in the space in a balanced manner. This is done by placing noise-absorbing material opposite the hard surface. The optimum result of echo removal is achieved when the acoustic material is placed close to speakers, like to the back and to the end of a conference table. The propagation of disturbing sound can be interrupted by placing the acoustic material at the sound reflection point. The best place is at the first sound reflection point +/- 40 cm.