Acoustic quality testing

What is acoustic quality testing?

In acoustic quality inspection, the (body) sound of objects or processes is recorded, analyzed and evaluated in order to draw conclusions about the quality of the object.

When components are acoustically stimulated  they produce a typical sound that can be used to detect inhomogeneities, cracks orinclusions  in the component. In other words, certain natural oscillations develop when a body is (acoustically) stimulated; these natural oscillations are influenced by "deviations" (e.g. defects such as cracks), provided that the defect significantly affects the structural properties of the component.

Even moving or rotating parts, as in machines, systems or motors, have specific operating noises when they function properly. A deviating noise behavior thus indicates a changed functionality or a faulty process.

The resulting signals are recorded and subsequently  evaluated and interpreted. For the evaluation and interpretation of the acquired sensor signals, methods from pattern recognition or based on artificial intelligence or machine vision can be used.

Door slam measurement Acoustic mapping
© Fraunhofer IZFP
Door slam measurement

Fields and applications of acoustic quality assurance

Fields of application

  • Inline monitoring of production processes
  • Control of finished products (end-of-line tests)
  • Continuous monitoring of production lines, e.g. for early detection of machine failures
  • Optimization of sound radiation from machines
  • Recommendations for noise reduction measures
  • Examination of noise propagation in production halls
  • Leak detection


  • Testing of gears, transmissions, etc.
  • Determination of the remaining service life of magnetic valves
  • Crack and impact detection for aerospace components
  • Condition monitoring of railroad wheels
  • Softness testing of paper
  • Structural deviations and joining errors
  • Differences in hardness
  • Delaminations
  • Pest detection in grain stores
  • Monitoring of compressors

Typical materials

  • Metal
  • Ceramics
  • Glass
  • Plastics
  • Composites
  • etc.

Fraunhofer IDMT

At Fraunhofer IDMT, methods for processing and analyzing acoustic signals are developed using artificial intelligence and machine learning.

Fraunhofer IZFP

At Fraunhofer IZFP test tasks from the field of acoustic quality assurance are processed, e.g.

  • Acoustic resonance and vibration analysis
  • Acoustic mapping