Holographic Sound Field Inspection Instrument

Macroscopic panoramic sound field perception—leaving abnormal noise nowhere to hide.

Introduction

In whole-vehicle NVH testing, the combined interference of expansive space, strong background noise, and dynamic operating conditions often makes the source of abnormal noise as hard to discern as “peering at flowers through fog.” Conventional acoustic imaging cameras have a fixed viewing angle and a limited field of view; when faced with a complex sound field, they can only repeatedly reposition and perform fragmented scanning—inefficient, and prone to missing key transient signals.

The Holographic Sound Field Inspection Instrument has risen to meet this need. With a proprietary spherical microphone array and AI multi-source blind source separation technology, it achieves 360°×180° dead-zone-free coverage of the whole-vehicle / cabin sound field in a single pass, precisely “catching” weak abnormal noise amid strong noise, and providing an efficient, visualized macroscopic source localization solution for fields including automotive manufacturing, rail transit, complex equipment, power, petrochemicals, and home appliance manufacturing.

Core Advantages: From “Local Scanning” to “Global Gazing”

Native omnidirectional coverage—no blind zones at all

Employing a spherical microphone array design, it physically achieves one-shot native coverage of hemispherical space (360° horizontal × 180° vertical), with no need for motorized pan-tilt rotation. A single deployment acquires full-domain acoustic data, adapting perfectly to strong reverberation environments such as confined cabins and complex interior trim, with not a single transient acoustic signal missed.

AI multi-source blind source separation—12 dB equivalent noise reduction

A built-in Blind Source Separation (BSS) AI algorithm precisely separates different independent sound sources (such as wind noise, tire noise, and BSR abnormal noise) from mixed acoustic signals without requiring any prior information. With an equivalent signal-to-noise ratio improvement of 12 dB+—like “super active noise cancellation”—it brings the weak abnormal noise (40–50 dB) that was originally masked by 80–90 dB road-test background noise “to the surface,” clearly discernible.

High-dynamic data acquisition and intelligent diagnosis

It supports a 25 Hz real-time refresh rate which, combined with time–frequency domain “freeze-frame” technology, can precisely lock onto random, transient BSR abnormal-noise events. The separated signals undergo AI-automatic feature extraction and classification (friction, knocking, looseness, etc.), substantially improving diagnostic efficiency and moving from “chaos” to “clarity” in a single step.

Efficiency revolution: full-domain troubleshooting from hours to minutes

Dispensing with the cumbersome conventional process of point-by-point scanning and multi-angle repositioning, a single deployment completes whole-vehicle-level panoramic sound field mapping, shortening hours of troubleshooting work to a matter of minutes—particularly suited to road-test abnormal noise, wind noise localization, and cabin sound field analysis.

Technical Principle: Holographic Sound Field Inspection, Building the Acoustic Perception Foundation

Centered on holographic sound field inspection and integrating AI algorithms, the Holographic Sound Field Inspection Instrument constitutes the underlying perception infrastructure of an acoustic world model. Its workflow consists of three steps:

1. Holographic sound field acquisition — the spherical array synchronously picks up sound pressure signals from all directions in space, acquiring the complete sound field distribution.

2. AI blind source separation — the BSS algorithm decouples the mixed noise, strips background interference, and extracts the target abnormal noise.

3. Sound field visualization and reconstruction — with an imaging accuracy of 4° resolution, the source position is mapped into an intuitive colored contour map, overlaid on the real-scene image in real time, achieving “what you see is what you hear.”

Typical Application Scenarios

• Automotive NVH testing: rapid localization of wind noise, tire noise, and BSR abnormal-noise sources during whole-vehicle road tests, covering areas such as the cabin interior, chassis, and tires.

• Rail transit: noise source identification and acoustic comfort analysis inside EMU trains and subway cars.

• Home appliance manufacturing: rapid abnormal-noise inspection on production lines for refrigerators, air conditioners, and similar products (in coordination with automated processes).

• Industrial monitoring of complex equipment: real-time localization of anomalous sources in strong-interference environments.

• Power and petrochemicals: power partial discharge, gas leakage, and equipment abnormal noise.

Technical Specifications

Notes: (1) The sensitivity figure of −24 dB is quoted without a reference basis (e.g., re 1 V/Pa or dBFS), and the 80 dB SNR figure without specifying whether it is a per-channel, array-level, or system-level value. (2) The ≥ 12 dB figure is designated as the “source separation signal-to-interference ratio” in this table, as “12 dB equivalent noise reduction” in Section II, and as an “equivalent signal-to-noise ratio improvement of 12 dB+” in the same section; the relationship among these three designations is to be confirmed. (3) The “frequency range 20 Hz – 20 kHz” figure is the microphone response range; the array’s effective imaging band and the frequency at which the 4° resolution is achieved are to be specified separately. (4) The 25 Hz figure is the sound field imaging refresh rate, which is distinct from the continuous acquisition sample rate that governs transient capture; the document does not state the acquisition sample rate.

Additional Notes

• Secondary development of core algorithms: deep integration of AI blind source separation with near-field / far-field acoustic holography technology, available for customized development;

• Engineering-grade reliability: the product has passed rigorous testing and validation by several mainstream automotive OEMs;

• Full-chain services: one-stop intelligent R&D closed-loop support spanning test scheme design, on-site deployment, and data analysis.

Conclusion

Let macroscopic abnormal noise become “clear at a glance”; let NVH testing bid farewell to blind zones and chaos.

The Holographic Sound Field Inspection Instrument—with a panoramic eye, discerning subtle anomalies.