【題組】38.
(A) When you are close to where the pebble fell, the waves are clearly in a circle, centeredon where the pebble fell.
(B) These arc measured to ensure compliance with laws that govemn acceprable soundemitted from a vehicle.
(C) Engineers can use several analysis techniques to identify aoise sources includingnear-field acoustic holography (NAH) and beamforming.
(D) Beanforming presents several challenges including simultaneously measuring a largenumber of microphone sensors, transmitling and saving this large amount of acquiredwavcform data, and being able to quickly process large data sets.