ASCEE proudly presents μZ, a state-of-the-art impedance tube designed for precise acoustic testing of small materials. Available in two sizes, with inner diameters of 20 mm (μZ-20) and 30 mm (μZ-30), μZ is ideal for researchers and engineers working with small acoustic material samples.
Key Features of the μZ Impedance Tube system:
- Comprehensive Solution: μZ includes all necessary software and hardware for seamless operation.
- Wide Frequency Range: μZ operates effectively within a frequency range of 20 – 6,000 Hz (30 mm inner diameter), or 20 Hz - 8,000 Hz (20 mm inner diameter) .
- Effortless Calibration: Our innovative calibration method allows for rapid calibration without the need to switch microphones, streamlining your testing process.
- Accuracy: μZ minimizes reliance on sensor and data acquisition specifications for its accuracy. This allows the use of small best-in-class MEMS microphones, which makes it possible to reduce the tube diameter without introducing internal reflections. This results in superior accuracy compared to traditional methods.
- Small system: μZ offers looser constraints on microphone spacing relative to the wavelength, allowing measurements down to 20 Hz with only ~ 400 mm of tube length!
Applications of the μZ Impedance Tube system
- Sound absorption measurement: Evaluation of the normal incidence sound absorption coefficient of small samples
- Acoustic material characterization: Characterization of the series impedance of thin materials such as meshes and membranes
- Quality control: Monitoring and ensuring consistent quality of acoustic products
Box Contents
When purchasing a μZ Impedance Tube, you receive a complete package that includes all required components. The box includes:
- Impedance tube + 4 MEMS microphones
- Wooden base support
- Calibration tube and end cap
- Sample holder (optional / custom) + 5th microphone. See info below
- Audio interface
- All required cabling
Measurement Capabilities
Measuring acoustic quantities at high standing wave ratios challenges conventional measurement procedures, e.g. based on the EN-ISO 10534-2:2023 standard. This capability is essential for reliably assessing the impedance of "almost-hard walls" or materials with high transmission loss. Our innovative approach utilizes 4 MEMS microphones (or 5 in case of high-impedance measurements) and an advanced calibration technique to determine the positions and sensitivities of the sensors.
The left figure below illustrates the measured input impedance of a 200 mm long tube with a hard end cap, measured with our 20 mm inner diameter tube. The impedance exhibits a dynamic range of nearly 80 dB, highlighting the challenges of measuring at high standing wave ratios. The frequency range is 20 Hz - 8,000 Hz.
The right figure below displays the computed normal incidence sound absorption coefficient (α) of the hard end cap. As shown, the computed α remains close to 0 over the entire frequency range of 20 – 8,000 Hz. This result is based on a single measurement. Note that, at 20 Hz, the wavelength in air is approximately 17 m, while our maximum microphone distance is only ~ 200 mm, which is significantly less than λ/10. Despite this, μZ still achieves good results at this frequency.
High Series Impedance Measurement Capabilities
By adding a microphone to the tip of the impedance tube, μZ can be used to characterize small acoustic meshes and membranes, with active diameters around 1 to 2 mm. This type of materials is typically used in hearables, such as hearing protection and earbuds.
In the high-impedance configuration, μZ is capable of measuring series impedances up to 1 GPa·s/m³. This is approximately 3100 MKS Rayls for samples with an active diameter of 2 mm.
The sample holder that's included with the μZ system will be customized based on the desired measurement range and the samples under test to optimize the system's performance for your application.
The figure below shows measurement data obtained from 5 samples of the same type of protective membrane. The measured impedance curves allow characterization of several material parameters, like the parasitic leakage, the compliance, the resonance frequency and damping.
Application notes
Application note AN: µZ-30 describes the testing acoustic membranes for leakage using μZ. Due to the application of these membranes, the applied sound levels needed to be very low, in order to prevent harmonic distortion. Despite this limitation, leaking membranes could clearly be distinguished from non-leaking membranes.Datasheets
- The μZ-20 datasheet is still Work In Progress. If you require any specific information, please contact us directly.
- Download the datasheet for the μZ-30 here.
More Information & Customization Options
Is the current μZ Impedance Tube system not quite what you need? We offer customization options to tailor the system to your specific requirements. Our team of experts is highly knowledgeable and skilled in the field of acoustics, ensuring that we can provide solutions that meet your unique testing needs.
Feel free to reach out to discuss your requirements, and let us help you design a system that perfectly fits your application. Whether you need modifications to the hardware, software, or specific features, we are here to assist you.