Josef Lechleitner

Measurements and predictions of room acoustics in atria

This study compares the acoustical measurements and simulation results of five atria with different designs. In each, atrium reverberation times and sound distribution patterns were obtained via measurements. Independently, we modelled these spaces using a room acoustics simulation application. The comparison of measurements and simulation results support the formulation of recommendations toward a more reliable use of modelling tools for proper acoustical design and analysis of atria.

Double Skin Facades with Natural Ventilation Capability: A Case Study of Acoustical Enhancement via Passive and Active (Noise Cancelling) Methods

Within an ongoing project, we explore the potential of double skin facades to provide both noise control and natural ventilation capability. Three strategies are investigated: i) Manipulation of sound paths via offset of the openings in the two shells of the façade; ii) Application of absorbing materials in the interstitial space of the façade; iii) Active noise cancelling methods utilizing wave-destructive interference. This contribution describes the overall project but focuses primarily on the active noise cancellation approach. Aside from a comprehensive background research on existing technology, we undertook the design of an actual setting for noise cancellation testing with suitable low-cost components as a proof-of-concept. Results of the experiments are expected to inform subsequent efforts to include noise-cancelling technology in double skin facades.

The Sound Insulation of Double Facades with Openings for Natural Ventilation

Natural ventilation represents a potentially sustainable scheme for the provision of good indoor air quality and free cooling in buildings. Noise pollution is an impediment in this case, as buildings under noise exposure cannot effectively deploy the natural (window) ventilation option. The present contribution focuses on a double-leaf facade solution, which offers sufficient sound insulation while facilitating natural ventilation. The impact of various variables of such a system (e.g., the size of the opening, location of the openings, the relative displacement of the openings in the two layers, the cavity sound absorption) were examined via parametric laboratory sound transmission measurements using an experimental modular double-leaf wall. An empirically-based equation and a simple analytical one were developed for the prediction of the sound insulation of double-leaf facades with openings for natural ventilation. The results of these computational estimations are compared with the measurements results to discuss the potential and limitations of their predictive performance.

Sound propagation in urban canyons: a case study of simulation reliability

Problems associated with increased urban noise exposure – especially due to road traffic – are well known. However, the acoustic planning of urban areas and the potential of simulation still does not receive sufficient attention. In this context, the present contribution focuses on urban canyons via comparison of measured and simulated sound levels. Toward this end, a room acoustic simulation tool was deployed to model two areas in the city of Vienna. Simulation results were shown to generally agree with the measurements. The contribution includes also a sensitivity analysis to explore the impact of variations in model assumptions on simulation results.