According to the text, there are six different acoustic classes that categorize areas based on their noise level. Class I represents areas where silence is a fundamental element, and these areas are particularly protected. Class II includes predominantly residential areas, while Class III consists of areas with a mix of uses. Class IV includes areas with mainly commercial and industrial activities. However, Class V and VI are exclusively industrial areas with limited residential areas. The noise levels for each class vary, with Class I at 50 dB(A), Class II at 55 dB(A), Class III at 60 dB(A), and Class IV at 65 dB(A). These classes are used to classify the noise level of a specific location based on its intended use.