Acoustic protection

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Our vision of acoustic protection


Confidentiality, respect for privacy and working conditions are particular aspects of daily life which impose on us an environment where noise nuisance must be reduced in order to enhance the company’s image, reduce the incidence of work-related illness and make the workplace a more attractive place to be.




Heinen has deployed its skills for the benefit of its customers, such as leisure centres, telecommunications companies, theatres, industrial companies, test centres etc. These customer wanted proper doors but with acoustic insulation, i.e. that are easy to handle and go through, and also look good.


This is what Heinen had in mind when it developed its doors: 7 cm thickness, extra-thin doorsills to allow heavy traffic to pass through easily and comfortably.





Sound is defined as an undulation. It is produced by transmitting a pressure wave within a solid, liquid or gas medium.


Like any undulation, a sound typically has 2 physical dimensions:

  • its intensity, expressed in decibels (dB)
  • its frequency, expressing the number of vibrations per second (Hz)

A distinction is made between the concept of sound in terms of the laws of physics and that which is heard by the human ear.


The ear does not have the same ability to detect slight variations in pressure for every frequency. To rectify this anomaly, weighting curves have been devised called A-weighting curves. When the sound level has been adjusted using this weighting curve, an A index is added to the decibel unit to give dB(A).



What we call noise is actually a juxtaposition of sounds at different frequencies. The level of noise fluctuates. When noise reaches a certain sound level, it becomes a real act of psychological aggression and can result in actual health problems.



Example: in order to achieve a quiet environment in premises looking out onto a very busy street, the noise level needs to be reduced by around 40 dB(A).


Turning national into European standards


In the case of Belgian standards, standard NBN S01-400 is the benchmark. It classifies the insulation of partitions in categories, from 1a to 4b. The letter a indicates acoustic protection and the letter b indicates places where acoustic protection is not a priority.


National standards are gradually being replaced by standard EN ISO 717-1. This standard summarises in a single index (Rw) airborne sound insulation in the frequency range from 125 to 4000 Hz.


Sound insulation of a wall


The R index, the calculation for which has been standardised by EN ISO 717-1, relates to the sound quality of a wall. This means the difficulty it has in transmitting airborne noise. It is only measured in the laboratory and only takes into account direct transmission (ignoring lateral transmission!). R is expressed in dB(A). It is measured across the whole spectrum from 100 to 4000 Hz.


The basic curve (in blue) is shifted dB by dB until the sum of the unfavourable values (pink dots beneath the green curve) is as high as possible, but lower than 10 dB across the 5 octave bands (32 across 16 third octaves).



The Rw value of the wall is 500 Hz on the shifted curve (green).



In the example shown in the graph opposite, the Rw value = 40 dB(A).





Two Rw adaptation terms have been created to take into account the properties of the noise source:


  • C is the adaptation for noise sources containing few low frequencies (rapid road traffic, children playing, daily activities etc.)
  • Ctr is the correction for noise sources containing lots of low frequencies (urban traffic, long-haul aircraft, discotheques etc.)

The sound reduction index R of a partition/door therefore really comprises three terms and is expressed as follows: Rw (C; Ctr)


Example: in the case of a partition Rw (C; Ctr) =37(-1; -3)

This means that the weighted reduction index is 37.


In the case of insulation against the noise of urban traffic, Ctr adapts the sound insulation downwards to 34 dB, and in the case of rapid motorway traffic, C adapts the sound insulation downwards to 36 dB.


If the type of noise present is initially known (through a noise analysis), Heinen can adapt a door to ensure that the downward C or Ctr adaptation is minimal. For instance, doors for a discotheque with lots of low frequencies.



Rw + C

Rw + Ctr

Bruit intérieur logements






Voies rapides



Bruit urbain



Avions à courte distance



Avions à grande distance




In situ losses

Acoustic scientists believe that the performance achieved in the laboratory is reduced by a minimum of 5 dB when a door is placed in situ.


In the laboratory, manufacturers do their best to actually fit the door in the ideal circumstances, unlike those on site where:


  • workers are not always experts at fitting doors
  • there are architectural defects (ground, walls etc.)
  • the sound insulation of the walls is not always adequate (the view is Rw walls = Rw of the door + 10 db)
  • it is not always clear how to measure performance in situ.



Heinen acoustic range


  • gamme des portes acoustique selon EN ISO 717-1
  • portes battantes simples ou doubles, pleines ou vitrées
  • châssis fixes, pleins ou vitrés
  • portes coulissantes
  • grandes dimensions : jusque 4x4m (même + grand)
  • verrou pression pour les grandes portes (pression optimale des vantaux contre le joint)
  • système de réglage de la compression des joints
  • avec sol libre (pas d’obstacle sur le sol) ou seuil minimum
  • large gamme d’équipements pour usages spécifiques (sorties de secours, contrôle d’accès, …)


By way of an example, the table below gives an overview of the performance levels that we can offer in hung doors:



EN 717-1
Rw (C ; Ctr) dB(A)

Porte simple pleine

36 (-1 ; -2)
39 (-1 ; -4)
46 (-2 ; -7)
52 (-2 ; -7)
55 (-2 ; -7)

Porte simple vitrée

44 (-1 ; -4)
46 (-1 ; -4)

Porte double pleine

44 (-1 ; -5)
46 (-2 ; -6)
49 (-1 ; -4)
53 (-2 ; -8)


Combination of performance features

Thanks to their modular structure based on Metal+, Heinen acoustic products can also have other performance features combined and added to them, such as: