Sound sensing through structural vibrations has emerged as a robust alternative to conventional air conducted microphones for automotive exterior applications, where environmental exposure can degrade microphone performance. This study evaluates the feasibility and performance of sensing airborne speech via vehicle body surface vibrations using surface mounted accelerometers. Three miniature accelerometers with different signal to noise ratios were mounted at seven locations on a vehicle body to sense speech generated by an artificial mouth positioned outside the vehicle. Speech quality was objectively assessed using ETSI TS 103 281 perceptual metrics under various driving conditions. The results demonstrate that acceptable to good quality of speech can be reconstructed from body surface vibrations under relatively low noise conditions such as parked or idling states. Accelerometer SNR is identified as a key performance factor, with higher SNR sensors consistently yielding superior speech quality across all mounting locations and test conditions. Sensor mounting location also plays a significant role, particularly under elevated driving noise, with relatively flexible and noise isolated body panels providing better performance. In addition, increasing the speech level improves performance, consistent with the benefits associated with higher SNR accelerometers. Finally, the results indicate that introducing a high pass characteristic into the accelerometer frequency response does not provide a consistent performance benefit.
