06 — CASE STUDIES

One node graph
is a methodology for an entire industry

18 scenarios, built from the same set of official acoustic nodes.

Pain PointsApproachNodes UsedExpected Output
NVH

NVH

8

Automotive · appliances · rotating machinery · environmental noise.

C01Powertrain / E-drive NVH teams

WOT Acceleration Order Analysis and Campbell Diagram

Resample the time-frequency spectrum into the speed-order domain to see at a glance which order sounds at which RPM.

Select channelOrder trackingSpectrum smoothingCampbell diagramSlice labeling
5 nodesView Case
C02Power / petrochemical / wind O&M · asset management

ISO 20816 Rotating-Machinery Vibration Zone Inspection

Turn the inspection of hundreds or thousands of motors/pumps/fans into a single chart: compute velocity RMS, apply Zone thresholds, and output a red-green status.

Channel split10–1000 Hz band-passVelocity RMSZone evaluationStatus dashboard
4 nodesView Case
C03Wind / chemical / steel predictive-maintenance providers

Envelope-Demodulation Bearing Fault Diagnosis

Envelope demodulation surfaces early bearing faults buried in broadband vibration, matching BPFO/BPFI/BSF/FTF characteristic frequencies on the envelope spectrum.

Resonance-band band-passEnvelope demodulationEnvelope-spectrum FFTCharacteristic-frequency matchingLabel verification
5 nodesView Case
C04Major-appliance / cleaning-appliance production lines

Appliance Sound-Power Compliance at End of Line

Multi-mic synchronous capture + A-weighting + one-third octave, synthesized into a single sound-power level L_WA with a PASS/FAIL result.

Channel splitA-weightingSound levelOne-third octaveSynthesize L_WAPASS/FAIL
6 nodesView Case
C05OEM sound-quality teams / Tier 1 interior trim

Psychoacoustic Sound Quality (SQ) Four-Metric Evaluation

The Loudness / Sharpness / Roughness / Tonality quartet quantifies "premium vs. cheap" perception into repeatable objective metrics.

Cut evaluation segmentsLoudness + Sharpness + Roughness + TonalityAlign and mergeComposite SQ score
7 nodesView Case
C06Environmental monitoring / occupational health / third-party testing

IEC 61672 Equivalent Sound Level and Time Statistics

A/C/Z weighting, Fast/Slow/Impulse, Leq/Lmax/Lpeak/statistical levels, and day-evening-night grouping are baked into the nodes for consistent re-measurement.

A/C/Z weightingFast/Slow/ImpulseStatistical levelsDay-evening-night groupingLimit evaluation
4 nodesView Case
C07OEM chassis / NVH teams

Road / Wind Noise Speed-Segmented Comparison

Split road-noise and wind-noise segments by GPS speed, then build a "speed × band" heatmap with consistent conventions to fairly compare states A and B.

Segment by speedLock ear positionA-weightingOne-third octaveSpeed × band heatmap
5 nodesView Case
C08Wind / data centers / energy storage / local environmental agencies

Long-Term Environmental Noise Compliance Monitoring

8h–24h outdoor recordings: equivalent level + narrowband-hum prominence (Tonality/TNR) + day-evening-night evaluation, built once and rerun long-term.

A-weightingEquivalent levelTonality + TNRDay-evening-night groupingLong-term compliance report
6 nodesView Case
EV

EV / New Energy

5

E-drive whine · AVAS compliance · the quiet sounds inside a pure-electric cabin.

C09Three-electric Tier 1 / OEM e-drive labs

EV E-Drive Electrical + Mechanical Dual-Order Analysis

Electromagnetic orders, mesh orders, and PWM sidebands are intermixed; extract orders separately in the mechanical and electrical domains and overlay them in a two-color Campbell diagram.

Split channelsMechanical-domain ordersElectrical-domain ordersTwo-color CampbellOrder slices
4 nodesView Case
C10OEMs + third-party type approval

AVAS Pedestrian-Warning Sound Compliance

Segment by speed, auto-fit the fundamental-frequency drift slope, check sound-level limits, and produce a PASS/FAIL result with a type-approval certificate page.

Operating-condition segmentationSpectrumFundamental drift fittingLimit evaluationCertificate page
5 nodesView Case
C11OEM sound-quality teams + Tier 2 trim / HVAC / door locks

EV Cabin "Small Sounds" Sound-Quality Evaluation

With the engine's masking gone in a pure EV, door-closing, air-vent, and rattle sounds are amplified; first auto-capture transient events, then run psychoacoustic evaluation.

Capture transient eventsLoudness + Sharpness + Roughness + TonalityFeature mergeAutoML discrimination (optional)
6 nodesView Case
C12Motor-plant lines / e-drive assembly EOL stations

EV Motor End-of-Line (EOL) Whine Evaluation

Run a short sweep on each unit at end of line, auto-extract whine orders and tonal prominence by RPM segment, and return PASS/FAIL within cycle time.

Order trackingTonal prominenceRPM-segment aggregationPASS/FAILSDK to MES
4 nodesView Case
C13OEM body / battery pack / seat Tier 1

Battery Pack / Structural-Part Buzz-Squeak-Rattle (BSR) Investigation

For the creaks and clacks (BSR) on a bumpy road or shaker table, auto-capture transients + psychoacoustic characterization to turn subjective complaints into comparable objective items.

Capture transient rattlesHighlight rattle bandSharpness + RoughnessOperating-condition alignmentArrange by condition
6 nodesView Case
CROSS

Cross-Domain Signals

5

The same operators, carried into healthcare · ecology · power · security.

C14Medical-device makers / primary care / AI-assisted diagnosis

Heart-Sound (PCG) Anomaly Screening

Carry the "time series + spectrum + anomaly" operators over to physiological signals: S1/S2 segmentation + murmur spectrum + AutoML normal/abnormal triage.

20–400 Hz band-passS1/S2 localizationMurmur spectrumMel featuresAutoML discrimination
5 nodesView Case
C15Nature reserves / NGOs / university ecology

Wildlife Acoustics / Birdsong Species Identification

Unattended long recordings: Mel spectrum + structure-tensor texture + AutoML multi-class species identification, producing an activity-rhythm data foundation.

Sliding-window segmentationMel spectrumStructure-tensor textureAutoML multi-classActivity rhythm
5 nodesView Case
C16Utilities / charging stations / UPS / power-quality testing

Current Harmonics and THD Analysis

Treat the "current WAV" as a time-series signal: FFT extracts harmonic spectral lines, computes each-order amplitude and THD%, and checks against the standard limit table.

Fundamental FFTEach-order harmonic + THD%Limit conformityLimit-line overlay
4 nodesView Case
C17Smart water / gas / energy audit / predictive maintenance

Pipeline Leak Acoustic Detection

For 20–40 kHz ultrasonic leaks inaudible to the human ear: baseline statistics model the normal distribution, and Z-Score auto-flags anomalies and alerts.

Ultrasonic band-passEnergy levelBaseline modelingZ-Score alerting
4 nodesView Case
C18Grid substations / transformer plants / condition-based maintenance

Transformer Core Hum Online Monitoring

The harmonics and modulation of a core's 100/120 Hz hum reflect loosening and DC bias magnetization: modulation spectrum + baseline deviation for 7×24 online early warning.

Frequency weightingModulation-spectrum analysisTNR prominencePer-unit baselineZ-Score early warning
5 nodesView Case
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