Technical Column
Precision Sound Power Measurements with ISO 3744 × HBK PULSE — Reliable Inverse Square Validation with SPAC and Certified Instruments —
2025年8月6日
- HBK × SONORA Acoustic Measurement Solution Official Website
- Technical Column
- Precision Sound Power Measurements with ISO 3744 × HBK PULSE — Reliable Inverse Square Validation with SPAC and Certified Instruments —
Acoustic Power Measurement
Introduction: Measurement Accuracy Depends on Both Room and Instrument
Sound power level (Lw) measurements under ISO 3744 require more than just high-end sensors or analyzers.
To meet the standard’s strict criteria—especially for validating the inverse square law (-6 dB attenuation)—you need:
- A properly designed test environment
- Precisely positioned microphones
- Analysis software that can evaluate the decay pattern
That’s why Moritani provides integrated systems combining HBK’s trusted PULSE platform and Sonora’s SPAC (Sound Power Anechoic Chamber).
Key Requirements for ISO 3744-Compliant Testing
- 1. Free-field or semi-anechoic environment (SPAC or VSAC)
- 2. Accurate microphone placement and distance control
- 3. Frequency-dependent attenuation analysis
HBK’s solutions, combined with Sonora’s room design, meet all these requirements—ensuring reliable, repeatable results.
System Configuration: SPAC × HBK Microphones × PULSE
| Component | Description |
|---|---|
| Room | SPAC: ISO-compliant free-field chamber for airborne noise testing |
| Sensors | HBK Free-Field microphones (calibrated, ±1 dB sensitivity) |
| Analyzer | PULSE software: Multi-point averaging, A-weighting, decay visualization |
| Optional Tools | Turntables, scanning rigs, elevated source tables for custom setups |
This combination ensures not only accurate Lw values, but also full traceability of inverse square behavior.
What Is the Inverse Square Law in Acoustics?
When the distance from a sound source doubles, the sound pressure level ideally drops by 6 dB.
This principle is used to verify the acoustic performance of the test room under ISO 3744 and ISO 26101.
With HBK PULSE, you can:
- Automatically calculate SPL drop between microphones
- Visualize decay curves across the frequency range
- Confirm standard-compliant free-field behavior in your test space
It’s not just data—it’s proof of environmental performance.
Real-World Applications
- Lw testing of motors, fans, pumps, and small machinery
- In-house compliance validation prior to product certification
- R&D use: comparative sound power measurements during prototyping
- ISO-compliant evaluation with third-party witness testing
SPAC and VSAC rooms are already adopted by leading manufacturers and are fully optimized for HBK instrumentation and workflows.
Consultation & Services
- Custom SPAC or VSAC design based on DUT size and test type
- Selection of compliant HBK microphones and accessories
- On-site support for room validation and inverse square law confirmation
- Calibration and integration services for full ISO traceability
Latest Posts in Technical Column
-
2025.08.11
Acoustic BOX Integration with HBK PULSE — Quiet Test Environments for Fully Automated Acoustic Inspection — -
2025.08.06
Precision Sound Power Measurements with ISO 3744 × HBK PULSE — Reliable Inverse Square Validation with SPAC and Certified Instruments — -
2025.08.01
Powertrain NVH Testing for EV and Mobility Applications — Multiaxial Measurement of Torque, Vibration, and Noise with VSAC × HBK Sensors — -
2025.07.16
The Logic Behind the Shape and Size of Anechoic Chambers -
2025.07.09
Why Build Your Own Acoustic Test Facility? SONORA × HBK: Designing Acoustic Spaces That Accelerate Innovation -
2025.06.25
The Truth Behind the 0.99 Absorption Coefficient : Understanding Cut-off Frequency and the Performance of Acoustic Wedges -
2025.05.27
How Quiet Is the Inside of an Anechoic Box? -
2025.05.27
Measured Sound Insulation Performance of Anechoic Enclosures in the High-Frequency Range -
2025.05.27
Anechoic Box and Sound Level Meter Demonstratio -
2025.05.27
Setting Background Noise Levels in an Anechoic Chamber
Contact Us
- Contact us by email
-
- Contact us by phone
-
Moritani Shokai
(Machinery Department No. 2, Tokyo Head Office)
Introduction of the Manufacturer
-
Hottinger Bruel & Kjaer
HHBK is a merger of two companies: Brüel & Kjær of Denmark and HBM of Germany.
Brüel & Kjær is one of the world’s leading manufacturers of acoustic and vibration measurement instruments, known as a total measurement chain supplier.Learn more about HBK
-
Sonora Technology Co., Ltd.
Sonora Technology is a leading Japanese manufacturer of industrial anechoic chambers and anechoic boxes.
From design and manufacturing to installation and acoustic performance assurance, Sonora provides fully integrated solutions to build complete acoustic measurement environments from the ground up.Learn more about Sonora
Contact / Request Brochure
For inquiries or consultations regarding the total solutions provided by HBK × Sonora, please feel free to contact us using the Contact button.
If you would like a brochure sent by mail, please use the Request Brochure button.