Sound insulation testing is the process for measuring the amount of noise that passes through a partition, which is usually a floor or a wall for building regulations testing purposes but could be a product such as a window or a door when testing using a sound insulation suite in a laboratory.

By understanding the sound insulation between two rooms separated by the partition, we find out how much noise is stopped by the partition in 16 different frequency bands and report them back to the end user as a single frequency result.

Sound insulation testing is not normally conducted on internal walls or floors within a property, though this does not mean that they are not required to have a level of sound insulation. Internal walls are required to perform at 40dB R_w in all home nations. Internal or intermediate floors are required to perform at 40dB R_w for England, Wales and Northern Ireland and 43dB R_w in Scotland.

Testing for internal sound insulation levels is not done as part of pre-completion testing as it is not possible to test internal partitions as there is always a doorway into the room which noise will travel around or through rather than the floor or wall, giving a false result.

The standard equipment used for sound insulation testing is:

Airborne test equipment:

Loudspeaker (can be passive or active)
Amplifier (if a passive speaker is used)
Sound level meter, usually with appropriate building acoustics software / module
Ear defenders

Impact test equipment

Tapping Machine
Loudspeaker (can be passive or active) – for reverberation time measurements only
Amplifier (if a passive speaker is used)
Sound level meter, usually with appropriate building acoustics software / module
Ear defenders

There are 4 mandatory standards for sound insulation testing plus 2 standards that provide additional guidance. It is noted that the BS EN ISO 140-4 and 7 standards as described below are called up in the home national building regulatory requirements and are still used despite being withdrawn and superseded.

Standards for Airborne Sound Insulation Testing

BS EN ISO 140-4: 1998 – Acoustics. Measurement of sound insulation in buildings and of building elements – Field measurements of airborne sound insulation between rooms

BS EN ISO 717-1:2020 – Acoustics. Rating of sound insulation in buildings and of building elements – Airborne sound insulation

Standards for Impact Sound Insulation Testing

BS EN ISO 140-7:1998 – Acoustics. Measurement of sound insulation in buildings and of building elements – Field measurements of impact sound insulation of floors

BS EN ISO 717-2:2020 – Acoustics. Rating of sound insulation in buildings and of building elements – Impact sound insulation

Additional Required Sound Insulation Standards

BS EN ISO 140-14:2004 – Acoustics. Measurement of sound insulation in buildings and of building elements – Guidelines for special situations in the field

BS EN ISO 354:2003 – Acoustics. Measurement of sound absorption in a reverberation room

Testing is normally conducted between habitable rooms, typically bedrooms and living rooms. However, it is not always the case that bedrooms and living rooms are adjacent and so testing is conducted between a habitable room and a non-habitable room, for instance a bedroom that is connected to a kitchen.

Sound insulation testers will try to mix and match the room types across a development to ensure they cover different room types and different facades where applicable. Hidden components, such as steel beams or voids, can reduce sound insulation and create paths for sound to travel with much less resistance. By changing the room types, the acoustic tester can assess whether these different facades are impacting the sound insulation.

This is a common question amongst testers looking to join SITMA. Technically, because the standards called up are still the BS EN ISO 140 series, the loudspeaker does not have to be omni-direction. However, SITMA strongly advises applicants to purchase an omni-directional speaker, as the BS EN ISO 16283 suite of standards which has superseded the BS EN ISO 140 suite of standards for sound insulation testing in the field does require an omni-directional source and with a quick regulatory change, testers could have to place an order for one and remove their existing source from their kit.  

Technically no, the reason why not is both simple and technical.

Firstly, the noise we measure is not the noise as the human ear hears it. We measure the energy created and stopped, not the perceived level of noise. For noise to be displayed as the human ear hears it, we apply a separate ‘rating’ called A Rating. This is typically displays as dBA.

Secondly, when measuring sound insulation, we measure across 16 separate frequencies from 100Hz to 3150Hz, though many testers measure beyond that range where possible. 100Hz to 3150Hz is broadly the range of human hearing. For a lot of acoustics measurements, we group the frequencies into frequency bands known as ‘octave bands’ (similar to a piano moving between A to G notes). For sound insulation, we use 1/3 octave bands (pronounced one third octave bands), which means each octave band is made up of 3 measured octave bands.

Technically we get a sound insulation test result for each of the 16 octave bands (1/3 octave bands) but that’s difficult to report and use for compliance, so we use the BS EN ISO 717 rating curve method to convert the 1/3 octave bands into a single frequency which makes it much easier for compliance purposes.

This does mean however that a partition will have good and bad parts. A wall may still meet its minimum requirements with very good high frequency performance and poor low frequency performance, meaning noise may still pass through the wall at low frequencies and it still be considered acceptable.

Sound insulation testing should ideally be conducted where the plots are complete to second fix with

1. Windows and doors installed.
2. Internal doors are installed and closable
3. 240v power is available in each room
4. The site is quiet enough to conduct the testing

The level of decorating is not important as this will not affect sound insulation.

Sound insulation test failures can be very expensive to repair, especially given poor advice.

For testing purposes, it is important to identify the cause of the failure and how many plots are affected so that all plots can be rectified. The Building Regulations will normally require testers to increase their sampling regime to support with the identification.

It is not acceptable to only make good the partition that failed, and not identify the root cause and repair any other examples of this construction on-site.