During the maintenance of nuclear power plants, it is important to reduce the radiation exposure of the workers. Auditory sensation has been widely used for alerting them to the radiation exposure such as personal dosimeters, which alert the user to radiation level by acoustic alarms. Although the measurement of radiation intensity has been more and more precisely, few study has focused on the selection of the effective alarm. The objective of this study therefore is to evaluate which acoustic feature is better for radiation dose reduction of nuclear power plant workers. There are three acoustic features used for conveying radiation intensity information in this study, which are: loudness, interval between alarm beeps and frequency. We conducted experiments to find which acoustic feature is effective. As the result, amplitude and frequency are relatively better acoustic feature for radiation reduction in long-term work because participants had lowest radiation exposure when using the frequency control alarm.