Acoustics is the science of sound and vibration. In automotive engineering, acoustics dictates how a car sounds to passengers and bystanders. Engineers spend years tuning the cabin acoustics to block tire whine and wind noise, while keeping the engine note pleasant during acceleration.
Exhaust acoustics is another major focus. Mufflers and resonators are designed using acoustic principles to cancel out harsh drone frequencies. They use internal chambers and perforated pipes to force sound waves to bounce off each other, cancelling out loud noises without restricting exhaust flow.
Technicians use acoustic diagnostics to find mechanical problems. A mechanic's stethoscope is a simple acoustic tool that isolates noises. By placing the probe on an engine block, the technician can hear a bad rod bearing or a squealing water pump pulley before taking parts apart.