This integrated single-station EoL test solution enables automotive HVAC air vent suppliers to perform NVH (noise/BSR), motor electrical testing, and vane presence detection in a single inspection step, helping to improve overall test efficiency and reduce labor dependency. System Block Diagram of the Automotive HVAC Air Vent Test Solution Modern automotive HVAC air vent assemblies increasingly integrate multiple drive motors, multi-row vanes (louvers), and smart features such as automatic airflow control and voice interaction. As a result, upstream process variation or assembly defects can translate directly into vehicle-level concerns—typically perceived as abnormal noise, buzz/squeak/rattle (BSR), airflow direction mismatch, or reduced airflow caused by missing/misassembled vanes. To reduce rework and prevent customer complaints, suppliers increasingly require 100% end-of-line (EoL) testing on the production line, covering NVH (noise/BSR), motor electrical testing, and vane presence detection. CRYSOUND Single-Station EoL Test Solution CRYSOUND’s automotive HVAC air vent EoL test solution enables customers to perform single-station, 100% testing of noise/BSR, motor electrical testing, and vane presence detection. The solution integrates CRYSOUND’s in-house hardware and software, CRY3203-S01 measurement microphone set, SonoDAQ, CRY7869 acoustic test box, and OpenTest. And it combines electroacoustic measurement with abnormal noise analysis (sound quality and AI-based algorithms) to identify noise/BSR issues that FFT and Leq may miss. It also integrates motor electrical testing and vane presence detection, enabling one-time clamping and a single OK/NG decision within the same sound-insulated EoL station. Schematic of the HVAC Air Vent Test Fixture Customer Results: Efficiency, Labor, and Quality Gains Replaced manual listening with machine-based detection, enabling unified criteria with quantitative, traceable results. One fixture, three test positions: supports parallel or mixed testing of left/center/right dashboard air vents, improving efficiency by >100%. Variant support via fixture changeover: reuse the same test station across different products, reducing repeated capital investment. One-operator, one-click inspection: a single line can save 1–2 long-term operators. EoL Test Equipment for Automotive HVAC Air Vent Typical Target Users This solution is designed for suppliers of motorized air vents and other motor-driven interior components，such as Valeo S.A.，Ningbo Joysonquin Automotive Systems Co., Ltd. and Jiangsu Xinquan Automotive Trim Co., Ltd. Main Hardware and Software Configuration ProductQty.NoteCRY3203-S01 Measurement Microphone Set1Measurement Microhone SetCRY5820 SonoDAQ Pro1Audio AnalyzerCRY7869 Acoustic Test Box1Test EnvironmentOpenTesthttp://www.opentest.com1SoftwareFixture1CustomizablePC & Monitor1(Optional) Feel free to fill in the form below ↓to contact us. Our team can share application-specific EoL testing recommendations based on your automotive HVAC air vent requirements.

In industrial production and environmental monitoring, excessive noise implies compliance risks or potential complaint disputes. To handle this, you need a professional sound level meter (SLM) that provides "credible, traceable, and analyzable data." Faced with price differences ranging from hundreds to tens of thousands of dollars, and a complex array of parameters, how do you choose without making costly mistakes? We have distilled the complex selection process into a "4-Step Decision Method" to help you quickly find the balance between your budget and your needs. Step 1: Define the "Purpose" — Does the data need to be externally accountable? This is the first watershed moment in selection, directly determining the equipment's "Accuracy Class." Scenario A: Data must be "Externally Accountable" Typical Use Cases: Environmental law enforcement, third-party testing, laboratory R&D, legal arbitration. Must Choose: Class 1 Sound Level Meter. Key Reason: The difference between Class 1 and Class 2 goes beyond reading errors. The core difference lies in the Frequency Response Range. Class 1 Devices (e.g., CRY2851): Typically cover a wide band of 10 Hz – 20 kHz, capturing extremely low-frequency vibrations and ultra-high-frequency noise, fully meeting strict standards like IEC 61672-1:2013 Class 1. Class 2 Devices: Usually have a narrower frequency range (e.g., 20 Hz – 8 kHz) with potential attenuation at high or low ends, making them unsuitable for strict metering or certification scenarios. Scenario B: Used only for "Internal Management" Typical Use Cases: Workshop inspections, equipment spot checks, community surveys, internal process comparisons. Recommended: Class 2 Sound Level Meter. Core Advantage: It meets the vast majority of industrial and environmental noise measurement needs and is the ideal choice for internal control. Step 2: Clarify "Indicators" — What exactly are you measuring?  Selecting the wrong indicators renders the data useless. Focus on the following two points: Frequency Weighting (A, C, Z): Which one to use? A-Weighting (Most Common): Simulates the human ear's response (insensitive to low frequencies). Must be used for Environmental Noise Evaluation and Occupational Health Assessments (e.g., 85 dB(A) limits). C-Weighting: Less attenuation at low frequencies, reflecting the total energy of the sound more truly. Often used for Mechanical Noise and Impact Sound where rich low-frequency components exist. Z-Weighting (Zero Weighting): Flat response across the entire frequency range with no attenuation. Must be used when you need Spectrum Analysis or deep research into noise components to preserve the original signal. "Instantaneous Value" or "Statistical Value"? For quick site checks: Focus on Lp (Instantaneous Sound Pressure Level) and Lmax (Maximum Sound Level). For scientific assessment or reporting: You must have Leq (Equivalent Continuous Sound Level). This is the core metric for evaluating noise energy over a period of time. Professional equipment (like CRY2850/2851) comes standard with integrating functions to automatically calculate Leq. Figure 1. Software Interface Diagram Step 3: Confirm if "Analysis" is needed — Do you need to find the noise source?  This distinguishes a "regular noise meter" from a "professional sound level meter." Looking at a total value (e.g., 85dB) only tells you "it's noisy here"; seeing the spectrum tells you "where is it noisy." When do you need Spectrum Analysis (1/1 Octave, 1/3 Octave, or FFT)? Noise Control: Determining if noise comes from a fan (aerodynamic noise) or a motor (electromagnetic noise). R&D: Comparing sound quality differences between competing products or iterations. Diagnostics: Distinguishing between high-frequency bearing squeal and low-frequency structural resonance. Selection Advice: Taking the CRY2851 as an example, it supports both OCT Analysis and FFT Analysis. If your goal is to "solve problems" rather than just "record numbers," be sure to choose a device with spectrum functions. Figure 2. Measurement Demonstration Step 4: Plan the Measurement "Mode" — Single measurement or long-term monitoring? Many projects fail because the device "measures accurately, but is hard to use." Dynamic Range: Say goodbye to "Manual Gear Shifting" Old equipment requires manual range switching, which is prone to errors. Modern sound level meters (like CRY2851) feature a >120 dB wide dynamic range, covering everything from whispers to roaring engines without switching gears—preventing errors and improving efficiency. Data Export: Ensure data is "Portable and Usable" Ensure the device supports automatic storage to an SD card or internal memory and exports in universal formats (like CSV). Avoid the trap of "measuring data but failing to record it manually." Remote Monitoring Capability (Essential for Outdoor/Long-term)  For long-term scenarios like construction sites or traffic monitoring, the device must have: Communication Functions: (LAN/Serial Port) for real-time remote data transmission. Outdoor Protection: (e.g., paired with NA41 Outdoor Kit, IP65 rating) to withstand rain and dust; otherwise, the equipment is easily damaged. Quick Selection Cheat Sheet To help you decide quickly, we have summarized three typical application scenarios based on the four-step method above: Figure 3. Handheld Measurement Operation The "Avoid Pitfalls" Checklist: Check these 5 points last Check the Standard: Confirm compliance with the latest IEC 61672-1:2013 standard. Check Bandwidth: Even for Class 2 meters, ensure the frequency range covers your main noise sources to avoid missed detections. Check Calibration: Buying a Class 1 SLM requires a Class 1 Sound Calibrator (e.g., CRY563A); otherwise, the system accuracy is downgraded. Check Range: Prefer "Wide Dynamic Range" or "Auto-Range" devices; refuse manual gear shifting. Check Accessories: Windscreens and protective cases are mandatory for outdoor use. Selecting a sound level meter is essentially balancing "Risk vs. Cost." If you still have doubts about "Class 1 vs. Class 2" or "Whether Spectrum Analysis is needed," CRYSOUND is ready to provide full lifecycle support: Pre-sales: Our application engineers provide one-on-one scenario consulting to help you match precisely and avoid wasting money. After-sales: We offer a full suite of services from calibration and training to long-term technical support, ensuring a complete chain of evidence. Instead of struggling with parameters alone, get in touch with our team using the form below to receive a configuration plan tailored to your application.

This article is for engineers working in acoustics and vibration testing. It introduces how to perform sound quality measurements in OpenTest based on the ISO 532 loudness standard and the ECMA-74 tonality evaluation methods. By measuring and comparing three key psychoacoustic metrics — Loudness, Sharpness, and Prominence (Tonality) — teams in consumer electronics, automotive NVH, home appliances and IT equipment can turn “how good or bad it sounds” into quantitative engineering data, and complete a standardized sound quality workflow on a single platform from data acquisition, through analysis, to reporting. Why Sound Quality Measurements Matter In traditional noise testing, we usually rely on dB values to describe how “loud” a device is. But more and more studies and real-world projects are reminding engineers that “loudness” is only part of the story. In automotive NVH, home appliances, IT equipment and consumer electronics, user acceptance of product sound depends much more on whether it sounds pleasant, sharp, tiring or annoying, not just the overall sound pressure level. Industry surveys also show that most manufacturers now treat “how good it sounds” as being just as important as “how quiet it is”, and they start paying attention to sound quality already in early design phases. At the same sound level, poor sound quality can significantly drag down overall product satisfaction. This is exactly why Sound Quality as a discipline exists: through a set of psychoacoustic metrics such as Loudness, Sharpness and Tonality/Prominence, it turns subjective impressions like “sharp”, “boomy”, “harsh” or “smooth” into data that is measurable, comparable and traceable, so engineering teams can go beyond noise control and truly design and optimize product sound around listening experience. Key Metrics in Sound Quality Measurement In engineering practice, sound quality is not a single number, but a set of psychoacoustic quantities. Commonly used metrics include Loudness, Sharpness, Roughness, Fluctuation Strength, Prominence/Tonality, etc. Figure 1 – Key metrics in sound quality measurement Loudness (ISO 532-1) Loudness and Loudness Level describe how loud a sound is perceived by the human ear, rather than just its sound pressure level in dB. Internationally, the ISO 532-1:2017 standard based on the Zwicker method is widely used for loudness calculation. It can handle both stationary and time-varying sounds and correlates well with subjective perception in many technical noise applications. From an engineering point of view, loudness has clear advantages over A-weighted SPL: It accounts for the ear’s different sensitivity to frequency (human hearing is more sensitive in the mid-high range) At the same dB level, loudness often tracks “does it feel loud or not?” more accurately Sharpness (DIN 45692) Sharpness reflects whether a sound is perceived as sharp or piercing. When the high-frequency content has a higher proportion, people tend to feel the sound is more “sharp” or “edgy”. Sharpness was standardized in DIN 45692:2009, and is typically calculated based on the specific loudness distribution from a loudness model, applying additional weighting in the higher Bark bands. The result is expressed in acum. In applications such as fans, compressors and e-drive whine, reducing sharpness often improves subjective comfort more effectively than just lowering the overall dB level. Roughness (asper) Roughness corresponds roughly to fast amplitude modulation in the 15–300 Hz range, which gives a “raspy, vibrating” impression — for example in certain inverter whines or gear whine where the sound feels like it is “shaking”. Unit: asper Classical definition: 1 asper corresponds to a 1 kHz, 60 dB pure tone amplitude-modulated at about 70 Hz with 100% modulation depth The deeper the modulation and the closer the modulation frequency is to the sensitive region (around 70 Hz), the higher the perceived roughness In engineering, roughness is often used to describe how much a sound feels like it is “buzzing” or “scratching”, and it is particularly relevant for subjective evaluation of technical noise in e-drive systems, gearboxes and compressors. Fluctuation Strength (vacil) Fluctuation Strength captures slower amplitude fluctuations — amplitudes that go up and down in the range of roughly 0.5–20 Hz, perceived as “pulsing” or “breathing”, with a typical peak sensitivity around 4 Hz. Unit: vacil A classical definition of 1 vacil: a 1 kHz, 60 dB pure tone with 4 Hz, 100% amplitude modulation In cabin idle “breathing noise”, or fans whose level periodically rises and falls, fluctuation strength is a key descriptor You can think of Fluctuation Strength and Roughness as two sides of the same “modulation” coin: Fluctuation Strength: slow modulation (a few Hz), perceived as “breathing” or “pulsing” Roughness: faster modulation (tens of Hz), perceived as “vibrating, raspy, grainy” Prominence / Tonality (ECMA-74) Many devices are not particularly loud overall, yet become extremely annoying because of one or two narrowband tonal components. These “sticking out tones” are usually quantified by Tonality / Prominence. In IT and information technology equipment noise, ECMA-74 specifies methods based on Tone-to-Noise Ratio (TNR) and Prominence Ratio (PR) to evaluate tonal prominence and to determine whether a spectral line is a “prominent tone”. Historically, these metrics come from psychoacoustic research and are now widely used in automotive, aerospace, home appliances and IT equipment to predict and optimize annoyance. For example, studies have shown that, with loudness controlled, Sharpness, Tonality and Fluctuation Strength are important predictors for the annoyance of helicopter noise. Why Sound Quality Is More Useful Than Just “Watching dB” In many projects, you may have already seen questions like these: Two fan designs have similar sound power levels, but one “sounds smooth” while the other has a clear whine After noise reduction, overall SPL is a few dB lower, but user feedback hardly improves On the production line, A-weighted SPL is used as the only criterion, and some “bad-sounding” units still slip through Fundamentally, that is because: Sound pressure level / sound power = “how much energy is there” Sound quality metrics = “how the ear feels about it” With metrics like Loudness, Sharpness, Roughness, Fluctuation Strength and Prominence, you can decompose vague complaints like “it just sounds uncomfortable” into: Which frequency region has too much energy (leading to high sharpness) Whether there is strong amplitude modulation (causing high roughness or fluctuation strength) Whether any tonal component is sticking out clearly above its surroundings (high tonality / prominence) In engineering iteration, these metrics can be mapped directly to: Structural optimization (stiffness, modes, blade shape, etc.) Control strategies (e.g. PWM frequency, fan speed curves and transitions) Material and noise treatment / isolation choices This gives you much clearer and more actionable directions than “just reduce dB”. Sound Quality Analysis in OpenTest As a platform for acoustics and vibration testing, OpenTest supports a complete sound quality workflow from acquisition → analysis → reporting. Fill in the form at the bottom ↓ of this page to contact us and get an OpenTest demo. Example Device: Office PC Fan Noise To make the process concrete, we use a very accessible device as our example: a typical office PC. Test objective: evaluate sound quality metrics of its fan noise under different operating conditions, in order to: Compare subjective noise performance of different cooling and fan control strategies Provide quantitative input to NVH reviews (e.g. does loudness exceed the target, is sharpness too high?) Build a foundation for further sound quality optimization (e.g. suppressing whine frequencies, smoothing speed transitions) Test environments might be: A semi-anechoic room / low-noise lab (recommended); or A quiet office environment for early-stage, comparative evaluation Measurement System: SonoDAQ + OpenTest Sound Quality Module On the hardware side, we use a CRYSOUND SonoDAQ multi-channel data acquisition system (for more detailed model information, please contact us), together with one or more measurement microphones placed near the PC fan or at the listening position, according to the test requirements. Figure 2 – SonoDAQ Pro multi-channel data acquisition system Of course, OpenTest also supports connection via openDAQ, ASIO, WASAPI and other mainstream audio interfaces, so you can reuse existing DAQ devices or audio interfaces for measurement where appropriate. On the software side, the Sound Quality module in OpenTest is one of the measurement modules. Combined with FFT analysis, octave analysis and sound level analysis, it can cover most standard audio and vibration test needs. Configuring Measurement Parameters After creating a new project in OpenTest, proceed as follows: 1. Channel configuration and calibration In Channel Setup, select the microphone channels to be used and set sensitivity, sampling rate and frequency weighting as required Use a sound calibrator (e.g. 1 kHz, 94 dB SPL) to calibrate the measurement microphones, ensuring that loudness and related metrics have a reliable absolute reference 2. Switch to the “Measure > Sound Quality” module Select the metrics to be calculated: Loudness, Sharpness, Prominence Set analysis bandwidth, frequency resolution and time averaging modes Optionally configure test duration and labels for different operating conditions Essentially, this step turns the “calculation definitions” in ISO 532, DIN 45692 and ECMA-74 into a reusable OpenTest sound quality scenario template. Acquiring Sound Data for Different Operating Conditions Once the test environment is set up and the parameters are configured, click Start to measure sound quality data under different operating conditions. Each test record is saved automatically for later analysis. Because sound quality focuses on how it sounds during real use, it is recommended to record several typical conditions, for example: Idle / standby (fan off or low speed) Typical office load (documents, multi-tab browsing, etc.) High load / stress test (CPU/GPU at full load) With this breakdown, engineers can clearly manage which sound quality result corresponds to which operating condition. Figure 3 – Overlaying multiple sound quality test records in OpenTest From Multiple Measurements to One Sound Quality Report After measuring multiple operating conditions (e.g. idle, typical office and full-load stress test), you can do the following in OpenTest. In the data set list, select the records you want to compare and overlay: Compare loudness curves under different conditions See whether sharpness spikes during acceleration or speed transitions Identify conditions where prominent narrowband tones appear (high prominence) In the Data Selector, save the associated waveforms and analysis results: Export .wav files for later listening tests or subjective evaluations Export .csv / Excel for further statistics or modelling Click the Report button in the toolbar: Enter project, DUT and operating condition information Select sound quality metrics and plots to include (e.g. loudness vs. time, bar charts of sharpness, spectra with marked tonal prominence) Generate a sound quality report with one click for internal review or customer submission Figure 4 – Example of a sound quality report in OpenTest The generated report includes measurement conditions and operating modes, key sound quality metrics such as Loudness, Sharpness and Prominence, as well as a comparison with traditional acoustic metrics (sound pressure level, 1/3-octave spectra, sound power, etc.), making it easier for project teams to discuss using a set of metrics that are both objective and closely related to perceived sound. Typical Application Scenarios You can build different sound quality test scenarios in OpenTest for different businesses, for example: Consumer electronics / IT equipment (laptops, routers, fans, etc.) Use loudness + sharpness + (where applicable) roughness to evaluate the “subjective comfort” of different thermal / fan strategies Compare sound quality across different speed curves or PWM schemes Automotive NVH / e-drive systems Use multi-channel acquisition to record interior noise and speed signals synchronously Combine order analysis with sound quality metrics to see how “sharp” an e-drive whine is and whether there is pronounced modulation causing roughness Home appliances and industrial equipment When sound power already meets standards, use sound quality metrics to further screen for “annoying noise”, instead of relying only on dB If you are building or upgrading your sound quality testing capabilities, you can use ISO 532 and ECMA-74 as the backbone and let OpenTest connect environment, acquisition, analysis and reporting into a repeatable chain. That way, each sound quality test is clearly traceable and much more likely to evolve from a single experiment into a long-term engineering asset. Welcome to fill in the form below ↓ to contact us and book a demo and trial of the OpenTest Sound Quality module. You can also visit the OpenTest website at www.opentest.com to learn more about its features and application cases.