EV NVH Testing Challenges: Why Acoustic Cameras Are Becoming Essential

Table of content


    Traditional NVH tools still matter, but they don’t cover every EV scenario-acoustic cameras fill the gap with real-time noise visualization and wide-band diagnostics.

    The Quiet EV Paradox: Why Electric Cars Are Actually "Noisier"

    It sounds like a paradox - electric vehicles have no roaring engine, yet engineers are finding it harder than ever to achieve a truly quiet cabin.

    The truth is, when the low-frequency masking effect of the internal combustion engine disappears, every previously hidden noise becomes fully exposed: the high-frequency whine of the electric motor, the electromagnetic hum of the inverter, gear meshing vibrations, wind noise, road noise, even the squeak and rattle of interior trim - nothing can hide anymore.

    This isn’t just a comfort issue. It’s fundamentally redefining the automotive industry’s approach to NVH (Noise, Vibration, and Harshness) testing.

    The global automotive NVH testing market is projected to grow from USD 3.51 billion in 2026 to USD 5.75 billion by 2034, at a CAGR of 6.4%. The core driver behind this growth? The electrification revolution.


    What New Noise Challenges Do EVs Bring?

    A Fundamental Shift in Frequency Range

    Traditional ICE vehicle NVH work focuses on the 20-2,000 Hz low-frequency range - engine firing, exhaust systems, crankshaft vibrations.

    Electric vehicles are fundamentally different:

    Noise SourceTypical Frequency RangeCharacteristics
    Electric motor electromagnetic noise500-5,000 HzSharp tonal noise, varies linearly with speed
    Inverter switching noise4,000-10,000+ HzHigh-frequency hum, related to PWM frequency
    Gear meshing noise800-3,000 HzParticularly prominent in single-speed reducers
    Battery charger noise8,000-20,000 HzNear-ultrasonic range, at the edge of human perception
    Wind / Road noise200-4,000 HzHighly exposed without engine masking
    ICE vs EV: The fundamental shift in noise frequency characteristics

    Key insight: EV noise problems shift from low frequencies to mid-high frequencies (and even ultrasonic ranges). The 100Hz-5kHz range is where most critical NVH issues reside-precisely where human hearing is most sensitive. Traditional NVH testing methods and frequency ranges may no longer be sufficient.

    New Noise Sources, New Localization Challenges

    In the ICE era, the assumption that "the engine is the dominant noise source" made things relatively straightforward.

    In EVs, noise sources become more distributed and complex:

    • Electric drive system: The motor + inverter + reducer form a highly coupled noise system
    • Thermal management: Battery cooling pumps and fans become dominant noise sources at low speeds
    • Regenerative braking: Changes in inverter operating modes during energy recovery produce transient noise
    • Structural transmission paths: Lightweight body structures (aluminum alloy, carbon fiber) have fundamentally different sound insulation characteristics compared to traditional steel

    This means engineers face a core challenge: How do you quickly and accurately locate the root cause among multiple distributed, dynamically changing noise sources?

    Sound Quality Design: From "Reducing Noise" to "Crafting Sound"

    NVH engineering in the EV era is no longer just about "minimizing noise."

    Consumers expect a carefully designed sound experience:

    • Acceleration should feel "high-tech" without being harsh
    • The cabin should be quiet, but not so silent that it makes the driver uneasy
    • Different driving modes (Sport / Comfort / Eco) should deliver differentiated acoustic feedback

    This demand for "Sound Design" is expanding NVH testing from pure engineering validation into subjective sound quality evaluation and brand-level acoustic identity.


    Why Acoustic Cameras Are Becoming Essential for EV NVH

    Facing these new challenges, traditional NVH testing tools - single-point microphones, accelerometers - remain important but are no longer sufficient for every scenario.

    Acoustic cameras are filling this gap.

    Core Advantages of Acoustic Cameras

    1. Real-Time Noise Source Visualization

    Traditional methods require densely placing microphone arrays on the target object - time-consuming and labor-intensive. Acoustic cameras use beamforming technology to generate a noise source heatmap in a single capture, instantly showing "where the noise is and how loud it is."

    Typical scenario: An EV prototype running on a test bench, the acoustic camera aimed at the electric drive system, instantly revealing that an 800 Hz resonance originates primarily from the right side of the motor - the entire localization process takes less than 5 minutes.

    
Engineer conducting noise source localization test

    Engineer conducting noise source localization test

    Automotive NVH detection and optimization

    Automotive NVH detection and optimization

    2. Wide Frequency Coverage

    EV noise spans from hundreds of hertz (gear meshing) to tens of thousands of hertz (inverter switching noise) - an enormous frequency range.

    Critical consideration for NVH: Most EV noise issues occur in the 100Hz-5kHz range-gear meshing, motor electromagnetic noise, wind leaks, HVAC systems. Traditional acoustic imaging cameras (limited to frequencies above 5 kHz) cannot capture these noise sources.

    Take the CRYSOUND SonoCam Pi (CRY8500 Series) as the ideal example: its 208 MEMS microphone array provides:

    • Beamforming frequency range: 400 Hz – 20 kHz (covers the entire NVH audible spectrum)
    • Near-field acoustic holography range: 40 Hz – 20 kHz (captures low-frequency road noise and structural vibration)
    • Array size: >30 cm (optimized for low-frequency spatial resolution)

    This makes SonoCam Pi uniquely suited for full-spectrum EV NVH testing-from low-frequency road noise to high-frequency motor whine, all in a single handheld device.

    3. Non-Contact Measurement

    EV electric drive systems are highly integrated and spatially compact. The non-contact measurement approach of acoustic cameras means:

    • No disassembly of any components required
    • No interference with the operating state of the system under test
    • Rapid quality inspection directly on the production line

    4. Portability

    Modern handheld acoustic cameras like the SonoCam Pi can be taken directly to proving grounds, production lines, or customer sites, no complex setup required.

    Typical Application Scenarios in EV NVH

    ScenarioApplication
    E-drive system NVHLocating order-based noise contributions from motors, inverters, and reducers
    Pass-by noise testingAnalyzing noise source distribution as vehicles pass by
    Interior squeak & rattle trackingLocating noise from dashboards, doors, seats, and trim
    End-of-line production QCRapid online detection of abnormal noise, replacing subjective human judgment
    Wind tunnel / Semi-anechoic chamberHigh-precision noise source localization and sound power analysis

    Real-World Case Study: OEM Dynamic Road Testing

    Client: A leading Chinese OEM
    Location: An OEM test center, internal test track
    Objective: Identify in-cabin noise sources during dynamic driving conditions

    CRY8500 Series SonoCam Pi acoustic cameras

    CRY8500 Series SonoCam Pi acoustic cameras

    Test Setup

    • Device:SonoCam Pi acoustic camera
    • Measurement positions:Rear seat and front passenger seat
    • Target areas:Left and right B-pillars (rear cabin area)
    • Test mode:Beamforming app
    • Frequency range:3,550 Hz – 7,550 Hz
    • Dynamic range:5 dB

    Key Results

    SonoCam Pi successfully localized noise sources in real-time during vehicle motion, providing actionable data for OEM’s NVH engineering team. The test demonstrated:

    1. Real-time localization during dynamic conditions: Unlike fixed laboratory setups, SonoCam Pi captured noise distribution while the vehicle was in motion on the test track
    2. Precise frequency-band analysis: By focusing on the 3,550-7,550 Hz range (critical for perceived cabin noise), engineers pinpointed specific contributors rather than measuring overall SPL
    3. Rapid testing workflow: Complete B-pillar area scan in minutes, not hours
    Automotive NVH test result in vehicle cabin
    
Noise source localization heatmap result

    Noise Source Localization Results

    Key Insight: Traditional microphone arrays would require the vehicle to be stationary in a semi-anechoic chamber. SonoCam Pi enabled on-track diagnostics, dramatically reducing testing time and enabling rapid iteration during vehicle development.

    Future Trends - What’s Next for EV NVH Testing?

    AI-Driven Noise Classification

    Machine learning is being integrated into NVH testing workflows: automatically identifying noise types, determining whether anomalies exist, and predicting potential quality issues. The high-dimensional data captured by acoustic cameras is naturally suited for AI analysis.

    Digital Twins and Simulation-Test Integration

    Simulation (CAE) predicts noise performance → Acoustic camera validates through physical measurement → Data feeds back to optimize the simulation model. This closed-loop approach is becoming the standard workflow for major OEMs.

    New Challenges in the Solid-State Battery Era

    Solid-state batteries have different mechanical properties compared to liquid lithium-ion batteries. Their vibration transmission characteristics and thermal management approaches will introduce new NVH challenges.

    Stricter Regulations

    Pass-by noise testing is the fastest-growing NVH sub-segment (CAGR 7.11%), with UNECE pushing for stricter standardized testing requirements, including indoor pass-by testing protocols.


    Conclusion: The Value of Acoustic Testing, Redefined for the EV Era

    Electrification hasn’t made cars quieter - it has made noise challenges more complex, more nuanced, and more valuable to solve.

    For automotive OEMs, Tier 1 suppliers, and testing service providers, investing in the right NVH testing equipment is no longer a "nice-to-have" - it’s foundational infrastructure for competitiveness.

    Acoustic cameras-especially those capable of capturing the critical 100Hz-5kHz NVH frequency range-are evolving from "useful auxiliary tools" to "indispensable standard equipment."

    The CRYSOUND SonoCam Pi stands out as the only handheld acoustic camera that combines:

    • Low-frequency capability (400 Hz beamforming, 40 Hz holography)
    • High spatial resolution (208 microphones, >30 cm array)
    • Near-field + far-field measurements in a single system
    • Portability (handheld, <3 kg, production-ready)

    Learn more:

    Detect Valve Leakage with Contact Ultrasound

    Valves are the "core control components" of pipeline systems. They perform four key functions—opening/closing, regulating, isolating, and directing—enabling precise control of fluid flow. Once sealing integrity fails, minor cases can lead to process upsets and energy losses, while severe cases may result in fires or explosions, toxic exposure, or environmental pollution. We built a valve leak application around the three things customers care about most on site—fewer missed detections and false alarms, better localization, and more reliable leak-rate estimation—by distilling them into an executable, traceable standardized workflow and closing the loop in the application for end-to-end deployment. Common Causes of Valve Internal Leakage What leads to valve leakage? We summarize it into the following four main causes: Normal wear and tear: Frequent opening and closing gradually wears the sealing surfaces; long-term scouring and erosion from the flowing medium can also degrade the seal fit. Process medium factors: Sulfur compounds and similar components in the medium can cause electrochemical corrosion; residual construction contaminants—such as sand, grit, and particles—can accelerate wear and scratch the sealing surfaces, leading to poor sealing. Improper operation and maintenance: Using an on/off valve for throttling, lack of routine cleaning and preventive maintenance, inadequate servicing, or improper/unsafe operation can all damage sealing surfaces or prevent full closure. Installation and management issues: Outdoor storage exposed to rain, ingress of mud and sand, and sandblasting/field conditions introducing grit or debris into the valve cavity can contaminate and scratch sealing surfaces, ultimately causing internal leakage. Figure 1. Illustration of Valve Internal Leakage When a valve is closed but the sealing surfaces do not fully mate, the pressure differential drives the medium to pass through small gaps from the high-pressure side to the low-pressure side, forming high-velocity micro-jets and turbulent flow. This leakage typically results in several observable signs, including sound/ultrasound, vibration, abnormal pressure behavior, and temperature anomalies or frosting. Figure 2. Symptoms of Valve Leakage Why Contact Ultrasound Works When a valve seal fails, high-pressure fluid passing through tiny gaps at the sealing surfaces generates turbulent flow, producing high-frequency ultrasonic signals in the 20–100 kHz range. The signal intensity is generally positively correlated with the leak rate—the larger the leak, the higher the amplitude. In the field, you can capture ultrasonic signals at measurement points upstream of the valve, on the valve body, and downstream, then apply algorithms to extract and analyze signal features to detect and localize internal leakage. Compared with traditional methods, temperature-based approaches are easily affected by heat conduction and are difficult to quantify; pressure-hold tests are time-consuming and poor at pinpointing the leak location; and listening by ear is inefficient, prone to missed detections and false alarms, and heavily dependent on individual experience. That's exactly why we launched this application—turning an experience-driven task into a standardized, process-driven workflow, supported by acoustics and data analytics. Figure 3. CRY8124 Acoustic Imaging Camera with IA3104 Contact Ultrasound Sensor Workflow and Key Capabilities More standardized workflow: turning on-site operation into guided testing In the CRY8124 valve leak application, the software features a standardized and visualized workflow. Operators follow on-screen prompts to place the contact ultrasound sensor on each measurement point in sequence and simply tap "Test". The results are displayed on the interface, and the algorithm automatically determines whether internal leakage is present after the test. Figure 4. Valve Leakage Detection Feature Page At the same time, the software provides standardized inputs for key parameters such as valve ID, valve type, valve size, medium type, and the upstream/downstream pressure differential. This means test results are easier to align across the same unit, different shifts, and different operators—making retesting and trend management much more consistent. Figure 5. Valve Leakage Detection Feature Page Smarter: automatic diagnosis + leak-rate estimation Our valve leak detection capability focuses on two key improvements: By analyzing the dB level at each measurement point and the features of the ultrasonic signal, the system automatically determines the internal leakage result based on algorithmic data, reducing reliance on manual interpretation. Built-in AI algorithms estimate the leak rate from ultrasonic features at the measurement points, providing a quantitative reference to support valve maintenance decisions. This is the core logic behind our emphasis on a "higher detection rate": when judgments rely less on subjective experience, missed detections and false alarms become far more controllable—especially in complex sites with many valves and multiple parallel branches. Application Scenarios Across different industries, there is a common need for valve leak detection: Figure 6: Application Scenarios Field Case Study Case : A Coal-to-Chemicals Plant in Inner Mongolia (Fuel Gas / Coal Gas System) Below is a real field test case of valve leak at a coal-chemical plant. Any internal leakage in fuel gas or coal gas systems can compromise isolation. If leakage exists, the downstream side may remain gas-charged, and the work area may still be exposed to risks of CO and sulfur-containing acid gases entering the zone—potentially leading to poisoning, fire, or even explosion hazards. Using contact ultrasonics, we performed on-site testing on the suspected valves, quickly identified the leakage points, and estimated the leak rate. This helped the customer turn "isolation confirmed" from an experience-based judgment into data-backed verification, prioritize corrective actions, reduce work risks caused by misjudged isolation, and ensure safer maintenance and stable operation. Figure 7. On-site Test Photos Valve type: Fuel gas compressor room bypass valve (butterfly valve). Test result: 19.8 L/min. Medium / pressure: Fuel gas (H₂, CO, CH₄), 3 MPa. Figure 8. Test Results Valve type: Fuel gas compressor room plug valve Test result: 1.7 L/min. Medium / pressure: Coal gas (mainly CO), 2.5 MPa. Figure 9. Test Results On-Site Test Method: Repeatable 5-Point Measurements Confirm Operating Conditions Ensure there is a pressure differential, and isolate interfering branches as much as possible. Key steps Close the valve to be tested. Open the upstream and downstream valves of the test section. Confirm a pressure differential between upstream and downstream gauges, and verify ΔP > 0.1 MPa. As shown in the figure below When testing Valve A for valve leakage: open Valves B and C, and close Valves A and D. When testing Valve B for valve leakage: open Valves A and C, and close Valves B and D. Figure 10. Valve Status Place Measurement Points (MP1–MP5) Cover upstream → valve core → downstream. MP3: Located at the valve core. MP2: Located 1–2 pipe diameters (D) upstream of the valve (place the point on the pipe wall away from the valve). MP1: Located upstream of the valve, 2–3D away from MP2. If space is limited, MP1–MP2 spacing can be shortened to 0.5D. MP4: Located 1D downstream of the valve (place the point on the pipe wall away from the valve). MP5: Located downstream of the valve, 1–2D away from MP4 (recommended on the pipe wall just after the valve flange). If space is limited, MP5–MP4 spacing can be shortened to 0.5D. D = pipe diameter Figure 11. Test Point Layout NoteFor small, flangeless threaded valves, the spacing between measurement points should be at least three pipe diameters (3D). Fugure12. Test Point Layout FAQ We've listed some common scenario-based questions about valve internal leakage to help you understand the application faster and choose the right solution more efficiently. Q1. How do I choose a Contact Ultrasound Sensor for pipelines at different temperatures? A1. We recommend the following sensor selection based on pipe surface temperature: For low-temperature pipes (below -20°C) or high-temperature pipes (above 50°C), use a needle-type Contact Ultrasound Sensor. For temperatures between -20°C and 50°C, use a ceramic Contact Ultrasound Sensor for signal capture. Q2. Which valves can be tested for valve leakage? A2. This method is suitable for valve leakage detection across a wide range of valve types, including: Gate valves Plug valves Globe valves Ball valves Check valves Butterfly valves Needle valves Pressure relief valves Pinch valves If your valve type is not listed above, please feel free to contact us. Q3. Can we still test if the valve and pipe are insulated? A3. If the insulation fully covers the valve and pipeline, testing may not be possible. You'll need to remove the insulation at the measurement area, or leave an opening of about 7 cm in diameter so the Contact Ultrasound Sensor can directly contact the pipe wall to capture the signal. Q4. What should we pay attention to regarding the pipe surface during data collection? A4. The Contact Ultrasound Sensor must make good contact with a solid surface to reliably capture ultrasonic signals propagating through the pipe. Large particles or debris between the sensor and the pipe surface can lead to inaccurate results. If the pipe wall is rusty, wipe off any large dust or loose particles on the surface before testing. Contact Us If you'd like to learn more about how CRYSOUND acoustics can be applied to valve leak detection, or if you want a more suitable inspection solution based on your on-site process conditions and acceptance criteria, please contact us via the form below. Our engineers will get in touch with you.

    Visualized Vacuum Leak Testing for Trains

    Negative-pressure airtightness is critical for high-speed train car bodies, and even minor leaks can lead to rework or delivery risks. This article presents a case from Changchun where CRYSOUND’s CRY8124 Acoustic Imaging Camera was used to quickly, intuitively, and verifiably pinpoint leaks on a carbon-fiber train car body shell, showcasing the CRY8124’s application in vacuum leak detection for carbon-fiber high-speed train car bodies. Case Snapshot Year: 2025 Location: Changchun Workpiece: Carbon-fiber train car body shell Test condition: Vacuum/negative-pressure setting; 15-minute pressure-hold test Sample size: 4 units Coverage: Scanned 6 key areas (car-body section joints/seams, structural interfaces, process holes, corners/curved transition areas, edge of cover film, around embedded components, etc.) Participants: CRYSOUND's Technical Engineers Deliverables: Acoustic imaging heatmap images/videos + report Project Background: Vacuum Leaks Are “Hard to Find, Time-Consuming, and Easy to Miss” Carbon-fiber car body shells feature complex structures with numerous joints and interfaces. When a leak exists during negative-pressure testing, traditional methods often face three common challenges: Experience-dependent localization: Requires repeated “listen–feel–try” steps, and heavily depends on operator skill and experience. High interference: Background noise from workshop fans, tools, friction, and impacts can mask weak leak signals. Inconsistent efficiency: Troubleshooting time varies significantly between operators for the same issue, making verification difficult. On-Site Approach: Pinpointing Leaks with “Visible Sound” In this project, CRY8124 Acoustic Imaging Camera was used to perform scan-based inspections across key areas of the shell. The core value of acoustic imaging lies in making the sound source generated by a leak visible on the screen—turning leak localization from “guessing” into “seeing.” On-Site Inspection Procedure: Maintain the negative-pressure condition: Troubleshooting was performed under the customer’s specified negative-pressure (vacuum gauge pressure approx. -100 kPa) test state. Selected frequency range: Based on on-site verification, 20–40 kHz was selected (offset from the dominant background-noise frequencies, providing better contrast for leak sources). Selected imaging threshold: Based on on-site verification, an imaging threshold of -40 dB was selected Scan and locate: Move the device along high-risk areas such as seams, interfaces, corners, and the edges of cover films. Point verification: Re-test suspected sound-source points at close range and mark them; adjust angles as needed for confirmation (strong airflow, film vibration, or strong reflections may create false leak indications, so multi-angle rechecks are required). Evidence output: Save images/videos with acoustic heatmap overlays to support on-site closure and quality documentation. Reports can later be generated using CRYSOUND’s second-generation analysis software. Inspection Results: Multiple Leaks Quickly Identified Under the customer’s specified negative-pressure test conditions at a train manufacturing site in Changchun, acoustic imaging scan inspections were carried out on a carbon-fiber train car body shell. Multiple vacuum leak points identified: A total of three suspected leak points were marked. Rechecks were performed using a temporary sealing (blocking) comparison method. After the leak points were sealed, there was no measurable pressure drop, confirming three leak points. All confirmed points were marked on-site, and images/videos with the leak heatmap overlays were saved for quality documentation and verification. Efficiency: On average, the total inspection time per component—from “start scanning” to “finish inspection, marking, and saving evidence / completing verification”—was under 10 minutes. Closed-loop validation: After corrective actions, a re-inspection was performed under the same conditions. The leak heatmap disappeared, and the workpiece passed the customer’s pressure-hold specification. From the on-site inspection visuals, different leak points consistently appeared as stable acoustic heatmap overlays on the device interface. Why Is Acoustic Imaging Well Suited for This Process? From the perspective of airtightness testing for composite structures, vacuum leak detection is not short of methods that can “find a problem.” The real challenge is achieving results that are fast, accurate, visual, and verifiable. In composite car-body applications, the advantages of acoustic imaging mainly include: Visual localization: Leak points are overlaid directly onto the surface of the structure as acoustic heatmaps, making the leak location visible and reducing communication and handoff costs. Stronger resistance to environmental interference: By selecting an appropriate frequency range and setting the imaging threshold, the contrast between leak sources and background noise is improved, minimizing the impact of ambient interference on results. More controllable efficiency: As a handheld tool, the cycle time is more consistent, making it suitable for batch inspections and production-line management. Traceable evidence: Images and videos can be retained for review, quality traceability, and training purposes. Practical Tips: How to Be “Faster and More Accurate” On Site Based on our on-site experience in Changchun, here are three actionable recommendations: Prioritize high-risk geometries: seams, hole edges, corners, cover-film edges, and interface transition areas. Image first, then verify up close: use the device to identify suspected leak points first, then confirm them at close range and from multiple angles. Standardize the documentation template: save images/videos for every point to support corrective actions, test report writing, and follow-up verification. Conclusion: Turning Troubleshooting from “Experience-Based Work” into a Standardized Process” In vacuum leak detection for carbon-fiber train car body shells, CRY8124 Acoustic Imaging Camera upgrades “listening for leaks” into visualized localization, delivering a closed-loop outcome with higher efficiency, clearer pinpointing, and retained evidence—while significantly reducing reliance on individual experience. If you’d like to learn more about the application of CRY8124 Acoustic Imaging Camera for vacuum leak testing, or discuss a detection solution better suited to your composite-material process and acceptance criteria, please contact us via the form below. Our sales or technical support engineer will get in touch with you.

    Wind Turbine Blade Vacuum Bag Integrity Test in 10 Minutes

    In this article, we use a wind turbine blade factory as an example to show how CRY8124 Acoustic Imaging Camera can help complete a vacuum (negative-pressure) integrity test for a single blade in about 10 minutes. What Is a Wind Turbine Blade? Wind turbine blades are the key rotor components that convert wind energy into mechanical power, which is then turned into electricity by the generator. They are typically made of glass-fiber or carbon-fiber composite materials and offer a high strength-to-weight ratio and strong corrosion resistance. The wind turbines you see on mountain ridges, in deserts, or along coastlines rely on these large blades to capture energy efficiently. Why Vacuum Bag Integrity Testing Matters in Vacuum Infusion In wind turbine blade manufacturing, vacuum bag airtightness during the vacuum infusion process is critical for stable vacuum levels and consistent laminate quality. Even small leaks can lead to process instability, additional troubleshooting time, and rework risk. A typical workflow looks like this: 1. Preparation: Lay auxiliary materials (release fabric, flow media), seal the blade with vacuum film, block openings with sealing tape, and connect the vacuum pump, lines, and a gauge. 2. Evacuate to target vacuum: Start the pump and ramp to the process-defined vacuum level. If the target cannot be reached or keeps drifting, check high-risk areas first (especially sealant joints). 3. Vacuum hold & leak check: After reaching the specified vacuum level, turn off the pump and begin the hold phase (typically 10–30 minutes). Confirm the vacuum loss stays within your acceptance limit. If there is a leak, the vacuum level will drop noticeably—locate the leak point and repair it promptly. 4. Repair, re-test, document: Mark the leak points, replace any damaged vacuum film, and reseal the leaking areas. After repair, repeat evacuation and the vacuum hold test until the system meets the acceptance criteria, then document the results before proceeding to the next step. Common Challenges in Wind Turbine Blade Vacuum Bag Testing A single blade can be 60–100 m long, creating a large sealing perimeter—so leak hunting can push the test beyond 30 minutes. Dense laminate around the blade root makes leaks harder to locate with traditional methods. Manual checks are slow and operator-dependent, leading to inconsistent results across shifts. Case Study: Faster Leak Localization and Lower Rework Cost At one blade manufacturer, routine vacuum-hold tests after bagging sometimes failed the hold criteria, leading to repeated troubleshooting and rework. The team introduced the CRY8124 Acoustic Imaging Camera as an assistive tool to locate leaks faster during pre-infusion checks. Recommended Settings (Example) Turn on the CRY8124 and select the vacuum/leak scenario. Set the acoustic imaging band to 20–40 kHz. Adjust the imaging threshold (-40 dB to 120 dB) based on on-site conditions to reduce background noise from fans, cutting machines, and vacuum pumps. If ambient noise is high, enable focus/beamforming mode to further suppress environmental noise. On-Site Leak Scanning Workflow During inspection, the operator walks along key areas—such as the pressure side (PS), suction side (SS), the main-spar region, and around the root preform—while holding the CRY8124 Acoustic Imaging Camera. When a leak is present, the device overlays an acoustic “cloud map” on the live video feed, helping pinpoint the leak location and reducing repeated manual checks. Measured Impact (Customer-Reported) After introducing the CRY8124 Acoustic Imaging Camera, the average vacuum bag check time per blade dropped from 30+ minutes to around 10 minutes (about a 70% reduction in check time). The customer also reported annual cost savings exceeding $10,000 by reducing rework and scrap. How a 10-Minute Vacuum Bag Check Is Achieved The CRY8124 Acoustic Imaging Camera is designed for fast scanning across common blade inspection zones (PS/SS surfaces, main spar region, and the blade root). It provides a visual indication of leak location and relative leak severity, while using frequency filtering and beamforming to work in noisy production environments. With a high-density microphone array (up to 200 microphones, depending on configuration) covering 2 kHz–100 kHz, the system can capture ultrasonic components from small leaks and render them as an intuitive acoustic image. If you’d like to learn more about acoustic imaging for vacuum leak detection—or discuss your blade process and inspection targets—please use the “Get in touch” form below. Our team can share recommended settings and an on-site workflow tailored to your production conditions.
    Acoustic camera line up

    What Is an Acoustic Camera? The Complete Guide to Sound Source Localization

    Acoustic cameras turn invisible sound into visible images. This guide explains how they work, where they're used, and how to choose the right one for your application. What Is an Acoustic Camera? An acoustic camera is a device that locates and visualizes sound sources in real time. It combines a microphone array — typically 64 to 200+ MEMS microphones arranged in a specific pattern — with a video camera and signal processing software. The result is a color-coded overlay on a live video feed, showing exactly where sound is coming from and how loud it is. Think of it as a thermal camera, but for sound instead of heat. Where a thermal camera shows hot spots in red, an acoustic camera shows loud spots — pinpointing the exact location of a leak, a faulty bearing, or an electrical discharge that you can't see with your eyes. The technology was originally developed for aerospace and automotive NVH (Noise, Vibration, and Harshness) testing. Today, it has expanded into industrial maintenance, energy utilities, manufacturing quality control, and building acoustics. How Does an Acoustic Camera Work? How an acoustic camera uses beamforming: sound waves arrive at each microphone with different time delays (Δt), the processor combines all signals, and outputs a color-coded sound map. The Microphone Array At the core of every acoustic camera is a microphone array — a precisely arranged set of MEMS (Micro-Electro-Mechanical Systems) microphones. The number of microphones directly affects performance: 64 microphones: Entry-level, suitable for general-purpose sound source localization 128 microphones: Professional-grade, better resolution and dynamic range 200+ microphones: High-end, capable of detecting subtle sources in noisy environments The spatial arrangement of these microphones matters as much as the count. Common configurations include circular, spiral (Fibonacci), and grid patterns. Each has trade-offs: spiral arrays offer good broadband performance, while grid arrays are better for near-field measurements. Beamforming: The Core Algorithm The key technology behind acoustic cameras is beamforming — a signal processing technique that combines signals from multiple microphones to "focus" on specific locations in space. Here's a simplified explanation: A sound wave arrives at each microphone at slightly different times (because each microphone is at a different distance from the source) The software calculates the expected time delay for every possible source location in the field of view For each candidate location, it shifts and sums the microphone signals according to the calculated delays Locations where the shifted signals add up constructively are identified as sound sources This process is repeated for every pixel in the image, producing a "sound map" that shows the spatial distribution of sound energy. Beamforming vs. Acoustic Holography There are two main acoustic imaging technologies: FeatureBeamformingAcoustic Holography (NAH)Best frequency rangeMid to high frequencies (>500 Hz)Low frequencies (<2 kHz)Measurement distanceFar-field (>1 meter)Near-field (<30 cm from source)ResolutionLimited by wavelength and array sizeHigher resolution at low frequenciesSpeedReal-time capableRequires careful scanningBest forLeak detection, general noise mappingEngine NVH, vibration analysis Most modern acoustic cameras use beamforming as the primary method because it works in real time and doesn't require the camera to be positioned close to the source. Some advanced systems support both technologies for maximum flexibility. The Role of the Video Camera The microphone array generates a sound map; the video camera provides the visual reference. The software overlays the sound map onto the video feed as a color-coded heat map, allowing the user to instantly see which component, pipe, or connection is producing the sound. High-end systems use depth cameras (such as Intel RealSense) to create 3D acoustic maps, enabling more accurate source localization on complex geometry. Frequency Range: Why It Matters Different applications require different frequency ranges: ApplicationTypical Frequency RangeWhyCompressed air leak detection20–50 kHzLeaks produce high-frequency hissingPartial discharge detection20–100 kHzElectrical discharges emit ultrasonic signalsMechanical fault detection1–20 kHzBearing wear, misalignment produce audible noiseAutomotive NVH100 Hz–10 kHzRoad noise, wind noise, engine noiseBuilding acoustics50 Hz–8 kHzLow-frequency structure-borne noise An acoustic camera with a frequency range of up to 100 kHz can handle virtually all industrial applications, including ultrasonic leak and partial discharge detection. Cameras limited to 20 kHz are suitable only for audible noise analysis. Key Applications Acoustic camera detecting vacuum leaks in composite materials — the color overlay pinpoints the exact leak location on the surface. Partial discharge detection on high-voltage insulators — the acoustic camera identifies discharge locations from a safe distance, combined with infrared thermal imaging for comprehensive diagnostics. 1. Compressed Air Leak Detection Compressed air is one of the most expensive energy sources in a factory. Studies show that 20–30% of compressed air is lost to leaks. An acoustic camera can scan an entire production line in minutes, identifying leaks that are invisible and inaudible to human ears. Why acoustic cameras beat traditional methods: Ultrasonic leak detectors require you to check one point at a time; an acoustic camera scans an entire area at once Visual overlay pinpoints the exact location — no guessing Many systems can estimate leak rate and annual cost, helping you prioritize repairs 2. Electrical Partial Discharge Detection Partial discharge (PD) is an early warning sign of insulation failure in high-voltage equipment — transformers, switchgear, cables, and bus bars. Left undetected, PD leads to complete insulation breakdown and potentially catastrophic failure. Acoustic cameras detect PD by capturing the ultrasonic emissions (typically 20–100 kHz) that accompany electrical discharge. The advantage over traditional PD detection methods: Non-contact: No need to de-energize equipment Real-time visualization: See exactly where the discharge is occurring Safe distance: Inspect live equipment from several meters away 3. Mechanical Fault Diagnosis Worn bearings, misaligned shafts, loose components, and valve leaks all produce characteristic sound signatures. An acoustic camera can identify and locate these faults before they lead to unplanned downtime. Common use cases: Motor and pump bearing wear detection Steam trap malfunction Valve leak identification Gearbox noise analysis 4. Automotive and Aerospace NVH Testing This is where acoustic cameras originated. NVH engineers use them to: Identify wind noise sources on vehicle bodies Locate rattles and squeaks in interior trim Analyze tire/road noise contributions Map engine noise radiation patterns Validate sound package effectiveness For NVH applications, large-aperture arrays (200+ microphones) provide the resolution needed to distinguish closely spaced sources. 5. Noise Compliance and Building Acoustics Environmental noise regulations require manufacturers to identify and reduce noise emissions. Acoustic cameras help: Map factory noise sources for compliance reporting Identify noise paths in buildings (walls, windows, HVAC) Verify effectiveness of noise barriers and enclosures 6. UAV-Mounted Acoustic Inspection A newer application: mounting acoustic cameras on drones for inspection of hard-to-reach infrastructure. Applications include: Power line and substation inspection Wind turbine blade inspection Pipeline corridor leak surveys Tall structure noise mapping Types of Acoustic Cameras Four form factors of acoustic cameras: Handheld (CRY8124), Fixed-Mount (CRY2623M), Large Array (CRY8500 SonoCAM Pi), and UAV-Mounted (CRY2626G). Handheld Acoustic Cameras Portable, battery-powered devices for field use. Typically 64–128 microphones with a built-in display. Best for maintenance rounds, leak detection, and quick inspections. Pros: Portable, easy to use, quick deployment Cons: Limited microphone count, smaller array = lower resolution at distance Fixed/Mounted Acoustic Cameras Permanently installed for continuous monitoring. Used in power substations, data centers, and critical infrastructure. Can run 24/7 with automated alerts. Pros: Continuous monitoring, automated alerting, no operator needed Cons: Fixed field of view, higher installation cost Large-Array Systems 200+ microphones on a larger frame. Used for NVH testing, pass-by noise measurement, and research applications. Often mounted on tripods or overhead structures. Pros: Highest resolution, widest frequency range, best for complex analysis Cons: Not portable, requires setup, higher cost UAV-Mounted Systems Lightweight acoustic arrays designed for drone mounting. Used for remote inspection of power lines, pipelines, and industrial facilities. Pros: Access to hard-to-reach locations, large-area surveys Cons: Flight time limits, vibration interference, regulatory requirements How to Choose the Right Acoustic Camera Quick decision guide: Choose your acoustic camera based on primary application. Step 1: Define Your Primary Application Your application determines the minimum specifications: ApplicationMin. MicrophonesFrequency RangeForm FactorCompressed air leak detection64Up to 50 kHzHandheldPartial discharge detection64–128Up to 100 kHzHandheld or fixedMechanical fault diagnosis64Up to 20 kHzHandheldNVH testing128–200+100 Hz–20 kHzLarge arrayContinuous monitoring64–128Application-dependentFixedDrone inspection64–128Up to 50 kHzUAV-mounted Step 2: Consider the Environment Noisy factory floor? You need more microphones and advanced algorithms to separate the target signal from background noise Outdoor use? Look for weather-resistant designs and wind noise rejection Hazardous area? Check for ATEX/IECEx certification Large distance? More microphones = better resolution at range Step 3: Evaluate the Software The hardware captures the data; the software turns it into actionable information. Key software features to look for: Real-time display: See the sound map live as you scan Frequency filtering: Isolate specific frequency bands to focus on particular issues Leak rate estimation: Quantify the cost of leaks in dollars or energy units Reporting: Generate professional reports with screenshots, measurements, and recommendations AI-assisted detection: Automatic identification of leak patterns and fault signatures Step 4: Compare Specifications Key specs to compare across manufacturers: SpecificationWhat It MeansWhat to Look ForMicrophone countMore mics = better resolution and sensitivity64 minimum; 128+ for demanding applicationsFrequency rangeDetermines what you can detectUp to 100 kHz for PD and ultrasonic leaksDynamic rangeAbility to measure both quiet and loud sources>70 dB for industrial environmentsAngular resolutionAbility to separate nearby sourcesSmaller is better; depends on frequency and distanceFrame rateHow quickly the sound map updates>10 fps for real-time scanningWeight and sizePortability<2 kg for handheld daily-use devicesBattery lifeRuntime for field use>3 hours for a full shift of inspectionsIP ratingDust and water resistanceIP54 or higher for industrial environments CRYSOUND Acoustic Camera Solutions CRYSOUND offers one of the widest product lines in the acoustic camera market — covering handheld, fixed-mount, large-array, and UAV-mounted form factors from a single manufacturer. Product Lineup CRY2624: 128-microphone handheld acoustic camera with ATEX certification — portable, field-ready, and safe for hazardous environments CRY8124: 200 MEMS microphones, frequency range up to 100 kHz — handles both audible noise analysis and ultrasonic applications (leak detection + partial discharge) in a single device CRY2623M: Fixed-mount version for 24/7 continuous monitoring of substations and critical infrastructure CRY8500 Series (SonoCAM Pi): Large spiral microphone array for NVH testing, pass-by noise measurement, and advanced acoustic research CRY2626G: Drone-mounted acoustic camera for remote inspection of power lines, pipelines, and wind turbines CRYSOUND acoustic camera product family: from handheld to drone-mounted solutions. Key Differentiator 1: Modular Sensor Expansion Unlike most competitors that offer a fixed-function device, CRYSOUND's acoustic cameras support external sensor modules for expanded capabilities: Infrared thermal imaging module: Combines acoustic and thermal data in a single view — when inspecting power equipment, engineers can simultaneously see the acoustic signature of partial discharge and the thermal hot spot of overheating components. This dual-mode inspection is widely used in power utilities for comprehensive substation diagnostics. IA3104 Contact Ultrasound Sensor: An external contact-type ultrasonic probe designed specifically for valve internal leak detection. The sensor couples directly to the metal surface of a valve, capturing high-frequency ultrasonic signals generated by internal leakage. Combined with intelligent analytics and guided workflows, it automates the full diagnostic process — from data acquisition to leak classification. This is critical for preventive maintenance of oil pipeline valves and natural gas network valves. This modular approach means a single CRYSOUND acoustic camera can serve as a comprehensive inspection platform, rather than requiring separate instruments for each detection task. Key Differentiator 2: Acoustic Link Mobile App CRYSOUND's Acoustic Link is a companion mobile app that connects to the acoustic camera via Wi-Fi. It enables: On-device preview: View captured photos, videos, and inspection reports on your phone or tablet — no PC required Defect-specific visualization: Retrieve gas-leak acoustic maps, partial-discharge patterns, and thermal images directly in the app One-tap sharing: Save results locally and share via the system share sheet for instant communication with colleagues and customers Automated report generation: Generate and export professional inspection reports from the field, eliminating the need to return to the office for post-processing For field inspection teams, this means faster turnaround from detection to documentation. Key Differentiator 3: Complete Acoustic Ecosystem Beyond acoustic cameras, CRYSOUND manufactures electroacoustic test systems (CRY6151B), acoustic test chambers, and calibration equipment — enabling complete acoustic testing solutions from a single vendor. With 28 years of experience and over 10,000 customers across 90+ countries, CRYSOUND brings deep domain expertise to every product. Explore CRYSOUND Acoustic Camera Products → Frequently Asked Questions What is the difference between an acoustic camera and a sound level meter? A sound level meter measures the overall sound pressure level at a single point. It tells you how loud it is, but not where the sound comes from. An acoustic camera shows both the location and the intensity of sound sources, making it far more useful for diagnosing and fixing noise problems. How far away can an acoustic camera detect a leak? Detection range depends on the leak size, background noise, microphone count, and frequency range. A typical handheld acoustic camera with 64–128 microphones can detect a 1mm compressed air leak from 10–30 meters away. Larger leaks can be detected from even greater distances. Can an acoustic camera work in a noisy factory? Yes. Modern acoustic cameras use beamforming algorithms that can isolate specific sound sources even in high-background-noise environments. The key is having enough microphones — more microphones provide better noise rejection and higher signal-to-noise ratio. Do I need training to use an acoustic camera? Basic operation is straightforward — point the camera, look at the screen, and identify the highlighted areas. Most users can start finding leaks within minutes. However, interpreting complex acoustic patterns (NVH analysis, partial discharge classification) benefits from training and experience. What is the ROI of an acoustic camera? For compressed air leak detection alone, the ROI is typically measured in months. A single quarter-inch air leak costs $2,500–$8,000 per year. Most industrial facilities have dozens to hundreds of leaks. An acoustic camera that helps you find and fix these leaks can pay for itself in the first survey. Can acoustic cameras detect gas leaks other than compressed air? Yes. Acoustic cameras can detect any pressurized gas leak that produces turbulent flow noise — including nitrogen, oxygen, hydrogen, natural gas, and refrigerants. The frequency characteristics may vary by gas type, but the detection principle is the same. Need help choosing the right acoustic camera for your application? Contact CRYSOUND for a personalized recommendation based on your specific requirements.

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