Powershield Acoustic
Noise is an ever-present by-product of modern living both in the external and internal environment, affecting our health and well-being.
Even low-level noise can have significant affects in the commercial environment, poor sound reduction between manufacturing and office environments can significantly affect productivity in terms of interference with speech and telephone use and even staff morale. In many situations such as conference rooms it is very important to reduce sound transmission in order to maintain confidentiality
Sound Solutions
Noise is 'unwanted sound', so the solution to noise is to change the sound environment, principally by reducing the level of sound produced. There are a multiplicity of solutions to noise reduction, but all rely mainly on two principles:
Sound Absorption, the process by which sound energy striking a surface is absorbed within the material and converted to heat energy.
Sound Transmission, which allows the transmission of sound energy from one point or space to another, via an intervening structure or passageway.
Both sound absorption and sound insulation (the opposite of transmission) are used in controlling the propagation of noise within and through buildings. This brochure describes the requirements necessary to achieve good sound reduction and hence noise control and how to specify sound insulation products.
Assessing Noise
Noise is 'unwanted sound'. The solution to a noise problem begins with assessing the noise impact. Sound can be described by its frequency (Hertz) and sound pressure level (decibels/dB).
Some examples of noise sources include:
| Bass beat in music | 80 - 160 Hz |
| Human speech | 300 - 3000 Hz |
| Violin | 200 - 3000 Hz |
| Electric motor | 200 - 8000 Hz |
| Rotary grinder | 500 - 4000 Hz |
| Pneumatic exhaust | 500 - 8000 Hz |
| Emergency siren | 2000 - 4000 Hz |
Examples of Loudness Perception
Sound Level
dB(A)
| 0 | Threshold hearing | Inaudible |
| 20 | Very rural environment Empty studio | Extremely quiet |
| 30 | Quiet home | Distant sounds audible |
| 40 | Quiet Office | |
| 50 | Background conversation | Moderate |
| 60 | Radio/Television in home | |
| 70 | Motorway noise | Moderately loud |
| 80 | Background factory noise | Loud |
| 90 | Noisy factory | Very loud |
| 105 | Discotheque | Deafening |
| 120 | Base drum at 1m | |
| 130 | Jet aircraft at 30m | Physical pain |
Examples of sound insulation
To maximise sound insulation, it is necessary to minimise vibrations in and through a structure and hence minimise transmission. The degree of sound transmission will depend on a number of factors: mass, stiffness and insulation.
Powershield Accoustic Doors are manufactured from steel, providing greater mass than other raw materials. Through extensive research our core materials and combinations have been developed to improve both insulation and stiffness.
The Air Gap Problem
Many sound insulation systems fail to meet the design specification due to the fact that although the insulating structure performs satisfactorily it is not perfectly sealed to the surrounding structure. A very small air gap can allow a very large amount of sound energy to be transmitted and hence cause an acoustic 'short-circuit'. For example, a 5mm gap at the bottom of a door capable of reducing sound transmission by 45dB would result in an overall sound reduction of only 25dB. In other words 250 times as much sound energy is transmitted underneath the door as through the door.
Even the slightest gap can materially reduce the sound attenuation performance of a structure and it is extremely important to consider not only the design of the door, but also the installation of the door and the design of the wall.
Click here to view a diagram that demonstrates Sound Reduction of Common Building Materials.
Rating of Sound Insulation
The sound insulation performance can be described over a range of frequencies as the Sound Reduction Index in dB. Powershield have developed a range of Acoustic Doors providing a variety of sound reduction capabilities. An example of the performance of a Powershield Acoustic AD5 Door, over the range of frequencies 100Hz to 3150Hz is shown in Diagram 2.
| Powershield Door | Rw | Performance | Description |
| AD1 | 20-25 | Minimal | Speech clearly audible |
| AD2 | 25-30 30-35 | Average | Normal speech understood Loud speech understood |
| AD3 | 35-40 | Good | Loud speech audible but not intelligible |
| AD4 | 40-45 | Very Good | Loud speech just detectable |
| AD5 | 45-50 | Excellent | Loud spech barely audible |
