Investigation of the Acoustic Comfort of an Academic Library: Case Study at the Technical University of Crete

The uses of academic libraries have been expanded in recent years to adapt to changes in technology and society. Various acoustic requirements are overlooked during the design process, leading to issues that need to be addressed afterwards. The present study is part of the acoustic renovation of the library of the Technical University of Crete, which arose after complaints from users due to its acoustic environment. To identify the library's acoustic issues, the following steps were followed: measurements of acoustic parameters were performed (according to ISO 3382–1), measurements of sound level metrics
$(\mathbf{L}_\text{Aeq}, \mathbf{L}_{10}, \mathbf{L}_{50}, \mathbf{L}_{90}, \mathbf{L}_{\text {AFmax }}, \mathbf{L}_{\text {AFmin }})$
were carried out in the library's interior and exterior under different conditions, observations were made regarding the uses of the library at various seating areas. Some of the most important results are the following:
$\mathrm{L}_{\text{Aeq}}$
is considerably higher than that suggested by the relevant literature (condition: average number of users), differences between
$\mathbf{L}_{10}, \mathbf{L}_{90}$
and
$\mathrm{L}_{\text{AF}\max},\mathrm{L}_{\text{AF}\min}$
are high which indicates large fluctuations in sound levels, reverberation time is slightly higher than that suggested by the literature which, although not the main problem, reinforces it. Observations in the library showed that the main reason for the acoustic issues is that due to the unified space, individual and group study areas coexist. Group study creates noise due to the inevitable conversation of the group members, which was found to be the most dominant noise source as well as the cause for the fluctuations in sound levels. To address these issues, several solutions are proposed, the most important of which are: dividing the library into zones (individual study, group study) and the placement of absorbent materials.