Building a Repeatable Acoustic and Vibration Measurement Chain for R&D and QA

In the field, many engineering teams face the same issue: datasets from tests that “should be identical” end up looking different. As a result, time is spent debating the data instead of improving the product. The key to solving this is to treat the measurement chain as an engineered system, not just a collection of instruments.

A good measurement chain should meet three objectives:

1. Repeatable: results can be reproduced and compared over time
2. Traceable: configurations and test conditions are documented
3. Scalable: you can add channels or sensor types without redesigning the architecture
4. Recommended measurement chain architecture

In practice, a measurement chain can be divided into four blocks:

• Sensor
  Acoustics uses measurement microphones. Vibration uses accelerometers.
• Signal conditioning
  Defines sensor powering, sensitivity, and noise protection. This includes IEPE requirements for accelerometers, as well as preamplifiers and powering schemes suitable for microphone measurements.
• Data acquisition
  Defines digitizing quality, channel synchronization, effective bandwidth, and PC connectivity method.
• Software workflow
  Defines channel configuration, engineering unit scaling, logging, and the analysis and reporting pipeline.
• Acoustics: what should be standardized

For acoustics, simple but effective internal standards typically include:

• Metric definitions: SPL, spectrum, tonality, pass/fail limits, or trending by operating condition
• Microphone position and distance from the DUT, including orientation
• Environmental conditions: room characteristics, background noise, and control of external disturbance sources
• Mounting method: consistent holder, stand, or fixture

The core principle is this: if geometry and conditions change, results change. Therefore, setup documentation should be treated as part of the test specification.

• Vibration: a stable baseline for industrial monitoring

For vibration measurement in machines and equipment, many teams choose industrial 100 mV/g accelerometers because they are easy to integrate and sufficiently sensitive for many use cases.

CTC AC102 is a multipurpose industrial accelerometer with 100 mV/g sensitivity, frequency response from 30 to 810,000 CPM, operating temperature range from -50 to 121 °C, and welded hermetic sealing. In practice, these characteristics make it suitable for monitoring and diagnostics on rotating equipment, as well as vibration validation on test stations that require sensors rated for harsh environments.

Key standardization items for accelerometers:

• Installation location and measurement axis direction
• Mounting method and consistent torque
• Cable routing and strain relief to avoid introducing mechanical noise
• Scaling and channel naming templates so datasets are easy to compare

• Data acquisition: combining acoustic and vibration in one platform

When acoustics and vibration are combined in a single test station, the most common issues are mismatches in:

• Bandwidth and sampling rate across channels
• Filtering and anti-aliasing
• Event synchronization when comparing phenomena that happen at the same time

NI CompactDAQ is often chosen for this type of requirement because it is modular, can combine multiple measurement types in one platform, and connects to a PC via USB or Ethernet. The recommended approach is to design the channel plan early:

• Define the number of acoustic and vibration channels
• Define the highest frequency of interest that is truly relevant
• Define synchronization requirements, especially for multi-point and multi-sensor setups

• Configuration practices that usually have the biggest impact

Below are simple practices that typically improve repeatability the fastest:

1. Create a “golden configuration”
   A single agreed channel configuration template. Operators select the project and run the SOP.
2. Define a sampling rule
   Sampling rate and filtering should follow the frequency targets. Do not rely on habit. Use the same rule for similar projects so datasets remain comparable.
3. Standardize connectors and accessories
   Reduce wiring variation to shorten setup time and lower the risk of wiring errors.
4. Treat metadata as part of the data
   Store information such as microphone distance, accelerometer orientation, test conditions, and configuration version.

• Analysis and reporting: from raw data to engineering decisions

To keep test stations productive, separate two needs:

• Stable logging for production or regression testing
• Advanced analysis for engineering investigation

For acoustics, a common pipeline includes time waveform, SPL, FFT, narrowband analysis, and limit comparison.

For vibration, a common pipeline includes time waveform, spectrum, band metrics, and trends versus speed or operating condition.

Most importantly, the final output must answer the test objective: pass or fail, parameter shifts, and the next action to take.

• Recommended quick implementation steps
• Define the main use case: validation, troubleshooting, or end-of-line screening
• Create a channel plan document: sensors, locations, units, sampling rule
• Build a prototype station and run a repeatability check
• Lock the configuration, then scale to the next station

If you want to build or improve a measurement chain for acoustic and vibration testing, the Haliatech team can support you from requirements through commissioning and workflow templates. For a quick overview before discussing requirements and test station configuration, you can also watch NI’s Acoustic Test Webinar Microphones via the link below.

Acoustic Test Webinar Microphones
https://forms.gle/ZTvv4eyxRQn3fSaB8

Contact our team to discuss technology solutions and your specific system requirements:
WhatsApp Sales: +62 821-2357-6487
Email: sales@haliatech.com
Office: (021) 22178880