Acoustic Specification

Sound Reduction values for walls are in accordance with BS 2750.

The Average Sound Absorption Co-Efficient for walls is in accordance with BS 3638 : 1963.

Sound Absorption refers to the amount of airborne sound energy absorbed on the wall surface adjacent to the sound.

Sound transmission loss is the total amount of airborne sound lost as it travels from one side of the wall or floor to the other.

Impact Sound Isolation refers to the number of decibels lost through a wall or floor from standardized impact.

Harney Masonry dense concrete blocks are particularly suitable for the reduction of airborne sound transmission and can be used to construct dividing walls in buildings.

The average sound transmission loss for concrete wall partitions when calculated over a frequency range of 100Hz - 3150Hz gives results between 44dB and 58dB depending on wall thickness and composition.

Double Walls perform better than single walls of equal weight. The sound transmission loss of a cavity wall is frequently about 8dB better than a solid wall of equal weight.

Data from Second Transmission Loss Tests of concrete Masonry Walls:

Wall Description Sound Reduction
100mm Solid Dense aggregate unit 44dB
140mm Solid Dense aggregate unit


215mm Solid Dense aggregate unit 50dB

250mm Cavity Wall

(100mm Wall & 50mm Cavity & 100mm Wall)


The importance of good standards of mortar jointing cannot be over-stressed if the desired standared of sound reduction are to be achieved.

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