Signal to noise ratio improvement of in situ absorption measurement using active noise control approach

It is important to have some information about sound absorption coefficient of already installed and applied materials. A new in-situ method is proposed. Presented method utilizes a dipole characteristic of the source. If the dipole is placed in vicinity of acoustical obstacle, sound field is deformed and it depends only on the acoustical properties of the obstacle. When using a real dipole source, asymmetry of dipole is present, so an active noise control approach was used to reduce this effect. Consequently this led to better measuring results and improvement of signal to noise ratio.