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TW AUDiO
EASE to IMMI workflow - a bridge between Sound Design and Noise Assessment
Years of research cooperation between AFMG Technologies GmbH, Wölfel Engineering, TW AUDIO and Akustik Bureau Dresden results in validated Aggregate Point Source (APS) Model — now integrated in EASE 5.
The Challenge: Balancing Experience and Impact
Event organizers and sound engineers strive for powerful, dynamic sound reinforcement that evokes emotions and creates a tangible live experience. However, planning open-air events is a balancing act: the goal of an immersive acoustic experience for audiences often conflicts with potential noise impact on residents.
For the resulting conflict of interest — realizing an emotional and simultaneously safe event for visitors while reducing sound emissions outward and adhering to applicable regulations — only unsatisfactory compromise solutions have been available to all parties involved. The fact that the two disciplines — sound reinforcement and noise immission protection — have previously spoken different "languages" complicates exchange and repeatedly leads to unnecessary misunderstandings.
Different Physical Approaches
The professional gap lies in the method of modeling: Electroacoustics and system design use calculation methods with coherent sources to determine sound pressure level distribution across the audience area. The radiation of a sound system always depends on the configuration and superposition of individual sources. The resulting interferences can be used to influence the radiation of the overall system. Using this approach, optimization parameters can be derived to precisely control individual sources — for example, for cardioid arrangements or through electronic beam steering. The focus here is on optimizing sound pressure level distribution in the audience area.
The assessment of sound immissions in Germany is subject to country-specific regulations. Calculations are based on normative specifications such as ISO 9613-2. They largely work with incoherent sources with defined directivity. The models are designed for static noise sources such as industrial plants and account for environmental variables such as wind, temperature gradients, and ground impedance. However, they can only inadequately represent the highly frequency-dependent and directional radiation of modern sound systems with multiple interacting sources.
The Core Problem: Methods Mismatch
Current sound system simulation software is highly precise in the audience area but largely disregards the influence of environmental parameters and radiation into neighboring areas. Conversely, immission forecasts aim to calculate and assess resident noise exposure on the safe side. However, these calculations ignore the complex superposition of individual speakers.
The Solution Approach: Integration Rather Than Abstraction
The solution lies in a methodological bridge: The Aggregate Point Source (APS) Model generates substitute sound sources based on detailed sound system simulation in EASE 5. Groups of coherently acting sources are combined as Aggregate Point Sources (APS). These APS precisely represent the far-field directivity of the underlying loudspeaker arrangement and serve as replacement sound sources in the forecast model, where they are summed incoherently. Data import and export are already fully implemented in EASE 5 and IMMI.
This creates a traceable and standards-compliant procedure with which the individual system configuration for the event in question can be analyzed and evaluated. This forms the basis for a transparent approval process. The result is a simulation chain that both ensures acoustic quality for the audience and creates the necessary transparency toward authorities and residents.
The APS approach has already been examined and validated in several publications. The results show that this method achieves practical forecast accuracy of approximately 1 to 3 dB. The approach is fully compliant with applicable standards.
In short: High-quality sound for the audience meets precise forecast models.
As part of these investigations, the TW AUDIO GLL models were fundamentally revised and verified. The investigations show that deviations smaller than 1 dB between measurement and simulation can be achieved with the new models.
The Aggregate Point Source (APS)-Model is the result of close collaboration between Tobias Goldmann from the TW AUDIO development team, AFMG, Wölfel Engineering, and Akustik Bureau Dresden. In this collaboration, scientific findings, simulation methods, measurements, and practical experience from different disciplines were combined to enable a process for realistic immission forecasting of modern sound reinforcement systems.
We thank our colleagues at AFMG, Wölfel, and Akustik Bureau Dresden for their collaboration and support.
This partnership impressively demonstrates that technological innovations in acoustics emerge where expertise, research, and practical application are brought together across company and discipline boundaries.
Further Information
Partners
- AFMG Technologies GmbH
- Wölfel Engineering GmbH + Co. KG
- Akustik Bureau Dresden Ingenieurgesellschaft mbH
Publications
- S. Feistel, J. Blaul, T. Goldmann, A. Nicht: "Sound immission modeling of open-air sound systems", AES 157th Convention, New York, Sep. 2024. Link
- J. Blaul, S. Feistel, T. Goldmann, A. Nicht: "Standard-Compliant Sound Immission Forecasts for Open-Air Music Events", DAGA 2025, Copenhagen. Link
- T. Goldmann, J. Blaul, S. Feistel, A. Nicht: "Modelling and Verification of Low-Frequency Sound Systems in the Application of Noise Predictions", AES 159th Convention, Long Beach, Oct. 2025. Link
- J. Blaul, S. Feistel, T. Goldmann, A. Nicht: "Cross-Software Workflow for Acoustic Assessment of Complex Sound Reinforcement Systems in the Context of Immission Forecasts", DAGA 2026, Dresden. Link
- A. Nicht, O. Gehler, M. Hädel, T. Goldmann, S. Feistel, J. Blaul: "Measurement-Based Validation of Forecast Calculations for Open-Air Sound Systems Regarding Direction-Dependent Sound Radiation", DAGA 2026, Dresden. Link
Software & Tools
