Application And Research On Improving Vehicle Interior Speech Intelligibility Using Sea Method

The vibration and noise level of the automobile is an important index for evaluationof the quality of automobile, which directly affects share of the car market. Acoustic packagescan effectively reduce the car interior noise and improve the speech intelligibility. Research ofacoustic packages is very important for the development of the new vehicles.Based on existing research achievements and previous engineering experiences, theacoustic package projects of one new sample car are studied using simulation and experimentmethods.First, NVH performances of the sample vehicle are tested. The sound pressure levels ofdriver’s right ear and left ear of passenger in right rear seat of the sample vehicle are higherthan that of the benchmarking car by 6.8d B(A) and 5.6d B(A), respectively when the airconditioner is turn on, and by 6.5d B(A) and 4.4d B(A), respectively when the air conditioneris turn off.. At the steady speed of 60 kmh, 80 kmh and 100 kmh, the above sound presuremeasured values of the sample vehicle are about 1.5d B(A) and 2.0d B(A) higher than that ofbenchmarking car, while the speech intelligibility are about 2.5% and 2.6% lower than that ofbenchmarking car. Then, based on the SEA theory and finite element model, absorptioncoefficient, insertion loss and loss factor are tested. The vehicle SEA model are establishedand calibrated to make sure the error was basically in the ±3d B range. Lastly, according tothe calculation results, sound absorption and insulation materials were added to the firewall, Bcolumn, carpet, channel and ceiling.After the improvement, no mater the air conditioner is on or off in idle condition, soundpressure levels of the improved vehicle are decreased 4~6d B(A), which basically reached thebenchmark level. When the sample car is driving at 60 kmh, 80 kmh and 100 kmh, the soundpressure levels of driver’s right ear are drop to 60.5d B(A), 63.6d B(A) and 64.6d B(A), whichare-0.2d B(A), 0.3d B(A) and 0.3d B(A) lower than the benchmark, respectively. The samplevehicle speech intelligibility are 92.3%, 87.4% and 80.9%, which are-0.2%, 0.1% and 0.3%higher than the benchmark, respectively. The sound pressure level of passenger position are63.3d B(A), 65.5d B(A) and 67.0d B(A), which are 0d B(A), 0d B(A) and-0.1d B(A) lower thanthe benchmark, respectively. The speech intelligibility are 92.0%, 88.2% and 83.2%, whichare-0.1%, 0.4% and 0.2% higher than the benchmark respectively. The sound pressure leveland speech intelligibility of the improved sample vehicle basically reached the benchmarklevel.