Excessive use of Personal Listening Devices (PLDs) and prolonged exposure to noise from loud music create many potential risks associated with hearing loss. To this end, the World Health Organization has published Recommendation ITU-T H.870 in 2019, which provides adults and children with a set of recommendations for sound dosage and operating times needed to avoid potential hearing risks. Some studies have investigated noise exposure of related applications for listening safety, resulting in some related recommendations and applications; however, these studies often do not pay attention to measurement error, which is important for human real noise exposure estimation to avoid hearing loss. This paper proposes a method for calculating noise exposure that can accurately calculate the actual noise sound-pressure level (SPL) and PLD dosage based on the WHO-ITU standard. We develop a calculation method and design a listening system that includes (i) a Safe Listening Personal Listening Device (SL-PLD) that can measure the listening dose in real time and control the output volume effectively, (ii) a Safe Listening Application (SL-APP) for assisting the SL-PLD to check the listening status in real time and provide alerts. Our experimental results show that (i) the proposed noise calculation method can reach 0.88 dB deviation under the 76 dB reference SPL and 98.8% accuracy, as compared to the SoundCheck tool measurement, (ii) the proposed SL-PLD controls the SPL output effectively as the dose increases, and (iii) the SL-APP determines the dosage usage and will provide a warning when the dosage exceeds a preset value. Therefore, users can adjust their listening behavior for more secure listening by using our methods and applications.