The pulp and paper industry is constantly striving to increase product quality and lowering the production costs. These efforts requires new or improved measurement techniques that either performs better than existing techniques or determines process parameters that at present cannot be determined. In the presented study we review a new photoacoustic technique that may have an impact in these matters. The photoacoustic technique is presented for two basic settings. The first is based on the effect that light absorbed in the fibre suspension generates sound through a thermoelastic energy transformation process. The sound wave, while propagating through the suspension, is distorted and attenuated by the fibres and thus inherently carries information about the suspension. The acoustic wave propagation is described mathematically and the model is used in an inverse manner to determine properties of the suspension and of the fibres, such as the fibre material elastic properties. The second setting includes monitoring of the scattered light intensity as well as its time-of-flight through the suspension. By combining the optical measurements and measurements of acoustic attenuation and speed of sound we have found that the combination can be used to give a good estimate of the total mass fraction as well as fiber and fines mass fractions. The proposed photoacoustic technique has potential to become a valuable tool for pulp and paper manufacturers enabling production of a more consistent product quality and further develop the understanding of the fiber elastic properties impact on the finished product.