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Measuring the Sound of Explosions in Norwegian Forests: How Validyne Transducers Supported Critical Acoustic Research
When it comes to understanding how sound travels through the natural environment, few conditions are as complex as a dense forest blanketed in snow—or alive with summer foliage. That’s exactly what researchers set out to study during a series of ambitious acoustic trials in Norway.
The goal? To track how impulse noise from explosive sources propagates through forested terrain across different seasons and environmental conditions.
The study brought together experts from four countries, involved over 30,000 individual measurements, and tested a wide range of transducers, sensors, and microphones. Among them was Validyne’s own P305D differential pressure transducer—a standout performer in rugged conditions.
Here’s how Validyne contributed to this international acoustic effort—and why it matters for researchers, defense agencies, and engineers alike.
The Study: Mapping the Sound of Blasts
The trials, detailed at the Internoise 1996 conference, were designed to measure how explosion noise moved through a forest during both summer and winter conditions. Measurement stations were spaced roughly 12 km apart, and collected an impressive array of data, including:
- Time histories of blast pressure waves
- Seismic activity
- Surface acoustic impedance
- Environmental variables (e.g., snow cover, vegetation density, wind)
Each station was equipped with multiple pressure sensors placed at varying heights. The study compared common high-end microphones—like B&K 4147 and 4193 models—with alternative technologies, including semi-conductor gages, piezoelectric sensors, and Validyne’s pressure transducer.
Enter Validyne: Rugged, Reliable, and Field-Tested
While traditional microphones performed well under controlled conditions, the real-world forest environment introduced challenges such as wind interference, temperature swings, and terrain variability. This is where Validyne’s technology made a difference.
The P305D differential pressure transducer was chosen for its:
- Low-frequency response (flat from DC to 200 Hz)
- High sensitivity, especially with the thinnest diaphragm configurations
- Custom adaptability, including a needle valve to create a reference pressure chamber for ambient pressure tracking
- Rugged design that tolerated cold, wind, and outdoor field conditions
Unlike microphones that can be delicate and expensive, Validyne’s pressure gage held up reliably in both the Norwegian summer heat and icy winter cold.
How Did It Compare?
In side-by-side tests with other devices, the P305D showed promising results:
In side-by-side tests with other devices, the P305D showed promising results:
- Compared to B&K Microphones:
While the B&K 4193 microphone exhibited some AC noise and the Chaparral microphone occasionally saturated, the Validyne sensor captured the key waveform features effectively—albeit with a slightly noisier signal and some signal drift. Still, it performed impressively given its cost and durability. - Compared to PCB and Kulite Sensors:
The Kulite and PCB transducers struggled with the sensitivity required for acoustic waves, especially in low-pressure environments. Validyne’s transducer was more responsive, able to detect pressure changes that others missed entirely. - Opportunities for Enhancement:
The study noted that future versions of the Validyne setup could benefit from on-board signal amplification to reduce noise and improve signal clarity. With that small upgrade, the P305D could become an even more powerful tool for field acoustics research.
Why It Matters
This study wasn’t just about noise—it was about how sound interacts with natural elements like snow, trees, and terrain. Understanding impulse noise behavior helps with:
- Designing safer military training grounds
- Predicting the environmental impact of explosions or loud machinery
- Improving long-range acoustic detection systems
And for Validyne, it showed that our transducers could stand up to the rigors of real-world research, offering a cost-effective alternative to pricier and more fragile equipment.
The Takeaway: Validyne Is Field-Ready
From the frozen forests of Norway to defense and research applications around the world, Validyne’s differential pressure transducers continue to prove their value. The P305D performed on par with high-end sensors, while delivering the durability, affordability, and adaptability needed for extended field work.
If your project involves environmental testing, impulse noise, or rugged acoustic measurement—let’s talk. We’d love to help you find the right solution.
The rugged P55 pressure transducer and transmitter offer cost-effective, reliable performance in demanding test environments. Designed to withstand extreme shock and vibration, the P55 delivers the high-level accuracy and consistency typically expected from more delicate differential pressure instruments.
As an upgrade to the P305, the P55 features active temperature and linearity compensation, achieving accuracies of 0.1% or better — roughly ten times more precise than the P305D. The P55D model is built for enhanced corrosion resistance, with wetted parts options including 316 stainless steel, Hastelloy, and Inconel. With a broader temperature range, improved media compatibility, and additional corrosion-resistant options, the P55 surpasses the P305 in both functionality and durability.
With variable reluctance sensing technology, the P55 pressure transducer delivers fast dynamic response, high resistance to vibration and superior signal stability through ambient temperature change for a wide variety of low-pressure to high-pressure measurements. The P55 pressure transducer will accept both liquids and gases directly at the sensing diaphragm – and there are no internal isolation fluids to slow the sensor response or cause excessive temperature drift errors.
Ready to explore our pressure transducers for your next project?
Contact us today or check out the P55 Product Page to learn more.
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