All types of trenching equipment regardless of engine size may be tested under this recommended practice. It is not intended to cover operation of safety devices such as backup alarms or accessories such as paving breakers. The sound levels obtained using this procedure are repeatable and representative of the higher range of sound levels generated by machines under actual field operating conditions@ but do not necessarily represent the average sound level over a field use cycle. Measurement and calculation of the operator's sound exposure should follow SAE J1166. Purpose - This recommended practice is intended to delineate test procedures for measurement of operator and exterior sound levels specifically for self-powered trenching equipment.