Sound Quality and Vehicle Condition
Research to evaluate sound signals inside trams has been undertaken using Brüel& Kjær binaural microphones, Time Data Recorder and PULSE data acquisition and analysis system. The tests were performed on a number of trams manufactured between 1908 and 2008, on normal town routes. Based on acoustical, spatial recordings, the initial quality of the design and the current technical conditions were evaluated. Normally for such recordings, a Head and Torso Simulator (HATS) and recording instrumentation would be used, which usually requires the vehicle removed from service. However, this is not always possible and is inconvenient. Good spatial recording, however, provides so much information about the vehicle that it is considered valua- ble not only for Sound Quality (SQ) analysis, but also for troubleshooting, maintenance and service work.
Sound Quality Recording the Easy Way
Now, complicated setup, the drawback of taking vehicles out of service and the considerable cost of traditional Sound Quality (SQ) recording and analysis systems are no longer a problem. The new SoNoScout NVH Binaural Recording and Analysis System can be taken for a tram ride in your pocket. It features the functionality of a HATS and comprises an extremely easy to use, handy recorder. SoNoScout offers high-quality, calibrated, binaural recordings along with GPS data indicating the vehicle position and speed. Data acquisition can be performed by anybody on a vehicle in regular service.
Operating the touch screen of the pocket PC, the operator only needs to establish the GPS signal, choose a name for the file and press start.
During recording, the operator wears standard mini headphones with built-in microphones positioned close to his ears. This results in a binaural recording, saved as a wave file along with the GPS position and speed. By seeming to be a normal traveller, the operator avoids unwanted attention from passengers or the driver. The data gathered can be used for analysis and post-processing. The software running in the pocket PC enables you to:
- Play back the sound
- Show the sound levels vs. time, as well as FFT and CPB spectra
- Plot the contour in 3D
- Filter the signals and play them filtered
- Track the RPM
- Plot the route and vehicle speed
The sound signal can be played back and analysed along with the GPS data and features a live cursor moving over the time and spectral plot. The same kind of analysis can be performed in the handy recording device and the PC software provided. Furthermore, the data can be analysed using more advanced tools such as the PULSE data acquisition and analysis system.