Investigation of the seat-dip effect using finite-difference time-domain simulations

Julie Meyer; Henna Tahvanainen; Jukka Saarelma; Tapio Lokki

doi:10.1121/10.0020826

Investigation of the seat-dip effect using finite-difference time-domain simulations

J Acoust Soc Am. 2023 Sep 1;154(3):1628-1639. doi: 10.1121/10.0020826.

Authors

Julie Meyer¹, Henna Tahvanainen¹, Jukka Saarelma¹, Tapio Lokki¹

Affiliation

¹ Acoustics Lab, Department of Information and Communications Engineering, Aalto University, 02150 Espoo, Finland.

PMID: 37702434
DOI: 10.1121/10.0020826

Abstract

The seat-dip effect (SDE) occurs when low-frequency sounds propagate through the seating area of a performance space. The physical aspects governing the effect still puzzle acousticians mostly due to the large variety of seating configurations. In this study, the SDE is investigated in three parameterized hall models using the finite-difference time-domain method to simulate a large number of seat configurations in order to quantify the contribution of different geometric properties related to the seating area. The results show that the step size defining the inclination angle of the seating area and the opening underneath the seats (or underpass) are significant factors contributing to the SDE, whereas the stage height and the source position are found to be less important. The results also demonstrate that with an underpass greater than the step size, the first frequency dip occurring between 80 and 100 Hz is mitigated regardless of the hall type considered. The phenomenon is also found to be predominant in the early part of the room response. Visualizations of spatial and time-frequency evolution in the halls are also provided for the cases where the seat properties are found to visibly affect the magnitude spectrum.