Fields of Application of sound absorption meter

The sound absorption meter AcoustiAdrienne (measuring system AED 800 + analysis software AED 801) serves the nondestructive measurement of

• sound absorption (sound reflection index and sound absorption coefficient) of a noise barrier / a sound screen in situ on the basis of the Adrienne method described in DIN EN 1793-5.

An extension of the sound absorption meter additionally allows the measurement of

• the transmission loss (sound insulation index) of a noise barrier / a sound screen in situ according to DIN EN 1793-6 (measuring system AED 810 + analysis software AED 811) as well as
• the sound diffraction (sound diffraction index, Miller index) at a noise barrier and its crown elements (Miller index difference) according to DIN EN 1793-4 (measuring system AED 820 + analysis software AED 821)

on-site. By means of an adapter, also

• the sound absorption coefficient of a sound absorbing road surface in situ according to DIN ISO 13472-1 (sound absorption coefficient > 0,15) as well as
• the sound absorption (sound reflection index and sound absorption coefficient) of a noise barrier / a sound screen according to DIN CEN/TS 1793-5 (measuring system AED 830 + analysis software AED 831)

can be determined in situ. Furthermore, the method is suitable to nondestructively measure

• the sound absorption coefficient of a sound absorber being installed in a room in order to reduce its reverberation time (e.g. wall absorber, ceiling absorber)

as well.

In contrast to the operation of the impedance tube AED 1000/1200 – AcoustiTube^®, the sound absorption coefficient cannot only be determined for perpendicular sound incidence, but also for statistical sound incidence.

By applying a specific model to consider the effect of sound diffraction at edges, these results can be directly compared to measurement results gained in the reverberation chamber according to DIN EN ISO 354.

Principle of sound absorption meter

In order to determine the acoustic properties of sound absorbers in situ, in each case two measurements have to be carried out, one measurement with specimen and on measurement without specimen (free field).

Exemplarily, from the first measurement of a sound absorption test with specimen an impulse response is calculated that contains a direct component, a reflected component of the specimen as well as further reflected components caused by surrounding obstacles. Latter ones can be excluded by application of a time window (Adrienne window). From the second measurement without specimen (free field) an impulse response is calculated that solely contains a direct component. Finally, the sound absorption coefficient and the sound reflection index of the specimen to be characterized can be determined by subtracting both calculated impulse responses from each other.

Principle of measurement of sound absorption coefficient of wall absorber by means of sound absorption meter AcoustiAdrienne in situ