GFAI Application Sound Analysis


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Noise emissions from a vehicle in a wind tunnel

Sound analysis and sound design using the acoustic camera

Sounds do not necessarily have to be loud to cause discomfort. In many cases, there are quiet sources far subordinate to the main sound, that nevertheless seem to be psychoacoustically dominating.

Some of the most significant examples for this phenomenon exist in the automotive industry, where the acoustic camera has already been in use with great success. Rattling, hissing, or clicking noises are undesired in any vehicle. Even at high speed, the pianissimo parts of classic music should not be drowned by driving noise.

Shutting the door, however, must produce a full sound despite the lightweight construction. There are similar requirements for the sound of car engines. The roar of a sports car or the sonorous sound of a sedan are typical distinctive characteristics of car brands. That's why big effort is spent to model the desired sound and to eliminate disturbances.

Sound issues are playing an increasingly important role also in household appliances. Some high-value products can already be identified by their "high-value sound". Noises that are usually associated with faults, like clicking, crackling or whistling sounds, can irritate customers and frequently lead to unnecessary complaints.

An entirely new dimension: Location-selective measurement of time and frequency
The acoustic camera can extend the time and frequency selectivity and add a location- selective component.

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With this method, not only the progression of the sound signal is shown, but a sequence of acoustic images can be acquired - acoustic films are generated. The analysis clearly shows which sound sources are active when and where. Extreme slow motion is possible, if required, up to a resolution of 192,000 images per second.


Engine sound in frequency-selective demonstration

It is possible to monitor ignition, intake and exhaust sounds of individual cylinders. Noise paths become visible, active sound sources and passive reflections are isolated. Entirely new insights and perceptions about the development of sound and noise can arise. It is also possible to analyze sounds from moving objects.

The acoustic camera extends and enhances existing analysis methods.
The acoustic camera comprises traditional analysis methods as well, like A-weighting, one-third octave band analysis and narrow band analysis, filters, and many more. Based on these methods far more detailed research becomes possible. In a spectrogram, for example, sounds can be highlighted in the time and frequency ranges. The acoustic camera then shows the exact origin of this sound. The approach can also be made from the other end: After selection of a spot on the measured object, the sound originating from that spot can be reconstructed, visualized and broken down into its spectral components. It is also possible to replay the sound via speakers - any time after the measurement is completed.