CENTROTECNICA

• Squeak & Rattle

During the latest years the sound absorbent materials used in motor vehicles have been noticeably improved, with an improvement in comfort due to the reduction of the noise heard inside the vehicle. As a consequence the noises produced by the structures or by the contact surfaces is much more audible.

The noise generated by the interaction of two or more surfaces in known as Squeak and Rattle. It generates acoustic signals which are considered both boring and bad for the corporate image.

OUR CAPABILITY:

Centrotecnica with Belotti Sistemi and the partner Ziegler Instruments has developed a new method (OCIAN), based on the non stationery loudness. It has proved to be very useful both for the identification and for measure of acoustic phenomena of S&R.
This method is actually appropriate for noise analysis on components in silent room; moreover it can provide the measure of the real absolute loudness level in the S&R event.

The method consists in:

Imposing a known profile vibration to the component under test with a noiseless shaker in a silent room with global sound level lower than 30 dBA
Detect the produced noises to be analysed with OCIAN system

The results give some normalised values upon a scale starting from 1 (excellent) to 10 (awful) which allow squeak & rattle phenomena to be objectively evaluated.

Ref: Ing. Andrea Cambiaghi