Advanced Transmission NVH Testing & Gear Optimization

Q: What is the minimum noise level you can measure?

Our semi-anechoic chamber has a background noise floor below 25 dB(A). We can accurately measure gear mesh tones and bearing frequencies well below the threshold of human hearing in a typical industrial or vehicle cabin environment.

Q: Can you test complete electric drive units (EDUs) or just gearboxes?

Yes. Our test cell is configured to evaluate complete EDUs including the electric motor and inverter. We specialize in separating electromagnetic noise (PWM switching) from mechanical gear noise to address the specific source of the complaint.

Q: Do you need a fully assembled vehicle for testing?

No. We can test bare transmissions or sub-assemblies on our dynamometer test stands. We use blocked-force characterization and transfer path analysis to predict how the component NVH will behave when installed in the final vehicle or machine.

Q: What kind of gear modifications can you recommend?

We specify modifications to gear macro-geometry (helix angle, pressure angle) and micro-geometry (profile crowning, lead modification, tip relief). All recommendations are validated for contact stress and bending fatigue to ensure durability is not compromised for NVH improvement.

Q: How long does a typical NVH investigation take?

A standard component-level NVH signature test with full order analysis and report delivery is typically completed within 3-5 business days. Complex root cause investigations involving iterative simulation and hardware modifications may take 2-4 weeks depending on scope.

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Transmission System Optimization & NVH Testing

AIMRSE provides advanced diagnostic and refinement services to resolve noise, vibration, and harshness NVH issues in custom gearboxes, electric drive units, and precision motion systems. Combining acoustic camera technology with proprietary gear micro-geometry optimization algorithms, we identify the source of objectionable tones and deliver validated engineering solutions that improve perceived quality and durability.

Our approach bridges the gap between subjective driver complaints and objective engineering data. Whether you are chasing a gear whine in an EV reducer or a bearing knock in an industrial gearbox, our semi-anechoic chamber and multi-channel data acquisition systems provide the clarity needed to quiet your transmission.

Schedule an NVH Assessment

Provide your target dB(A) limits or describe the audible complaint. We will propose a test plan to quantify the issue and develop a noise reduction roadmap.

Discuss NVH Project

Initial test data consultation within 48 hours.

ISO 16916 / AGMA 6000 Gear Accuracy & NVH Standards

Anechoic Chamber Background Noise < 25 dB(A)

Order Analysis LMS/Head Acoustics DAQ

KISSsoft Optimization Micro-geometry Modification

Core NVH & Transmission Optimization Capabilities

Acoustic & Vibration Mapping

Near-field acoustic holography and tri-axial accelerometer arrays pinpoint noise sources. We separate gear mesh harmonics from motor PWM tones and bearing defects.

Gear Micro-Geometry Optimization

Calculation of optimal profile crowning, lead slope, and tip relief to minimize transmission error (TE) and static transmission error (STE) under loaded conditions.

Modal Analysis & Resonance Avoidance

Experimental and FEA-based modal testing of housings and shafts. We recommend structural modifications or mass dampers to shift natural frequencies out of operating ranges.

Torsional Vibration Analysis

Measurement of angular acceleration at the input and output shafts to diagnose coupling misalignment, universal joint phasing errors, or engine firing order excitation.

Sound Quality Metrics

Beyond simple dB(A), we evaluate psychoacoustic parameters (Loudness, Sharpness, Roughness, Tonality) to ensure the "sound signature" aligns with premium brand expectations.

End-of-Line NVH Screening

Development of automated pass/fail criteria and test stand parameters for production line quality assurance, ensuring every shipped gearbox meets your noise specifications.

Semi-Anechoic Chamber & Dynamics Testing Center

AIMRSE's NVH facility is purpose-built for the precise quantification of rotational and structural noise. The controlled acoustic environment eliminates background interference, allowing us to capture low-level gear whine and bearing defects that are inaudible on a noisy factory floor.

Semi-Anechoic Chamber with Chassis Dyno
Capable of absorbing sound reflections down to 100 Hz. Integrated with a high-speed dynamometer capable of simulating vehicle coast-down, acceleration, and constant-speed cruising profiles up to 15,000 RPM.
Multi-Channel Data Acquisition System (LMS Scadas / Head Acoustics)
Simultaneous sampling of 32+ channels including microphones, accelerometers, and laser vibrometers. Real-time FFT and order tracking provide immediate feedback on dominant noise orders and harmonic content.
Acoustic Camera with Beamforming Array
High-resolution localization of sound sources on complex gearbox surfaces. Overlay of acoustic heat maps onto 3D CAD models pinpoints exactly which bearing or gear mesh is generating the objectionable frequency.
KISSsoft / MASTA Simulation Suite
Advanced loaded tooth contact analysis (LTCA) software. We correlate simulated transmission error curves with measured NVH data to fine-tune micro-geometry modifications for optimal quietness and durability balance.

Semi-anechoic chamber and acoustic camera array for transmission NVH testing and order analysis Fig. 1. Semi-anechoic chamber equipped with chassis dynamometer and acoustic camera array.

Featured Transmission NVH Optimization Application

The Challenge

High-Frequency Gear Whine in Electric Vehicle Single-Speed Reducer

An EV startup encountered a pervasive 2.8 kHz whine during highway cruising speeds (80-100 km/h) in their new production-intent drive unit. The noise, originating from the final drive helical gear set, failed subjective jury evaluations for "premium cabin quietness" and risked customer satisfaction scores. Initial prototype gear sets with standard DIN 3962 Grade 6 quality showed inconsistent NVH performance batch-to-batch.

The Solution: Micro-Geometry Optimization and Manufacturing Process Control

AIMRSE performed order analysis in the semi-anechoic chamber, isolating the 23rd order gear mesh harmonic. Loaded tooth contact analysis (LTCA) revealed a narrow contact pattern under high torque, causing high transmission error. We developed a new micro-geometry specification including a 5 µm barreling modification and optimized tip relief. Furthermore, we established a correlation between measured waviness on the gear flank and the 2.8 kHz amplitude, enabling tighter production process controls at the grinding stage.

Validated Reduction in Cabin Noise and Improved Sound Quality

9 dB(A) Reduction at 2.8 kHz

Post-optimization vehicle tests confirmed a 9 dB(A) reduction in the dominant whine order, making the tone inaudible under background wind and tire noise. Subjective ratings improved from "Unacceptable" to "Transparent." The refined micro-geometry also increased calculated surface durability by 12% due to improved load distribution.

See more solutions for New Energy Vehicles & Rail Transit →

Frequently Asked Questions — Transmission NVH & Optimization

What is the minimum noise level you can measure?

Our semi-anechoic chamber has a background noise floor below 25 dB(A). We can accurately measure gear mesh tones and bearing frequencies well below the threshold of human hearing in a typical industrial or vehicle cabin environment.

Can you test complete electric drive units (EDUs) or just gearboxes?

Yes. Our test cell is configured to evaluate complete EDUs including the electric motor and inverter. We specialize in separating electromagnetic noise (PWM switching) from mechanical gear noise to address the specific source of the complaint.

Do you need a fully assembled vehicle for testing?

No. We can test bare transmissions or sub-assemblies on our dynamometer test stands. We use blocked-force characterization and transfer path analysis to predict how the component NVH will behave when installed in the final vehicle or machine.

What kind of gear modifications can you recommend?

We specify modifications to gear macro-geometry (helix angle, pressure angle) and micro-geometry (profile crowning, lead modification, tip relief). All recommendations are validated for contact stress and bending fatigue to ensure durability is not compromised for NVH improvement.

How long does a typical NVH investigation take?

A standard component-level NVH signature test with full order analysis and report delivery is typically completed within 3-5 business days. Complex root cause investigations involving iterative simulation and hardware modifications may take 2-4 weeks depending on scope.

Silence the Competition. Optimize Your Drivetrain.

A quiet transmission is a reliable transmission. Whether you need to diagnose a field issue or proactively refine a new product before launch, AIMRSE's NVH experts and semi-anechoic lab provide the objective data and engineering support you need to meet world-class sound quality targets.

Schedule an NVH Consultation

For urgent drivetrain noise troubleshooting or test lab rental inquiries, contact our dynamics group at info@aimrse.org.

Disclaimer: All products are for industrial B2B use only. Specifications subject to change without notice.

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