Project title: Calibration of mems microphone array systems for room acoustic data collection

Description:

The development of compact microphone arrays, particularly those based on MEMS (Micro-Electro-Mechanical Systems) microphones, has become increasingly important in a wide array of applications, ranging from noise monitoring to room acoustics characterization. MEMS microphones offer significant advantages, such as cost-effectiveness, small form factors, and impressive improvements in sensor accuracy in recent years. Their miniaturized size allows for the creation of light-weight easy-to-handle microphone arrays that do not disturb the sound field even at high frequencies. This is crucial for maintaining the fidelity and quality of collected sound data, particularly in applications where accurate measurements are critical, such as measurement of sound absorption properties, particularly in-situ. Additionally, the low production cost of MEMS microphones makes them an attractive option for large-scale deployments in both research and commercial applications.

However, despite their potential, there are still challenges that limit the full realization of MEMS-based microphone arrays. One of the main issues is the lack of established calibration procedures for these devices, which is a prohibitive factor for their reliability in practical applications. Without accurate calibration procedures, it becomes difficult to ensure that the microphone arrays deliver sufficiently accurate and reproducible data across different environments and applications over a large frequency range. Despite these challenges, the versatility of MEMS microphone arrays in noise monitoring, sound localization, and sound absorption measurements is clear. Through advanced array processing techniques, they can offer valuable insights into spatial sound patterns and room acoustics, making them indispensable in fields such as environmental noise assessment, architectural acoustics, and even sound visualization. Therefore we aim to research calibration procedures and sensor optimizations in terms of the size of the array and number of microphones, which will eventually constitute a solid ground for unlocking the potential of these compact microphone arrays for room acoustic applications. In this 2-month project, we will mainly focus on the calibration of a couple of MEMS microphone array prototypes and combination with the developed software that can estimate the absorption properties of a wall in-situ. This acoustic characterization is extremely useful for acoustic practitioners and here Gade-Mortensen Akustik is enthusiastic to follow the development of the prototype and can provide useful industrial perspectives over the project time and even after the project duration.

Project Activities

1. Define the project scope (MEMS microphone technology, array size, accuracy threshold)
2. Testing a version of the microphone array
3. Develop and refine the calibration procedure
4. Collect sound field data near a surface of interest using the calibrated array
5. Infer acoustic properties of the surface, e.g., surface impedance/admittance, reflection coefficient
6. Analyze the feasibility/plausibility of the data
7. Identify drawbacks and benefits compared to the state of the art or standardized methods
8. Documentation and report

Contributions from the industrial partners

1. Company partner: Gade Mortensen
   • Share real-life challenges in engineering consultancy
   • Commenting on the needs for such a device and wishes in terms of usability of the device
   • Point out some potential applications
   • Share its perspective on the device and the array solution
   • Share the trends of the acoustic engineering consultancy

Duration:

Start: 15 April 2025
End: 23 Juni 2025
Funding: 162.500 DKK