1. A record player for playing an acoustical record, said record player comprising: a base; a platter rotatably mounted on said base and configured to support the acoustical record thereon; a tonearm assembly pivotally mounted on said base and configured to read the acoustical record for producing sound stored by the acoustical record; and a monitoring unit secured on said base, and including a light emitter configured to emit light toward said platter, an image capturing module configured to receive the light reflected by said platter and to capture images of said platter, and a processing module configured to receive the images of said platter from said image capturing module, and to determine a current rotating speed of said platter by analyzing and comparing the images captured by said image capturing module at successive time points.