Previously published research suggests that PLD users often choose volumes as high as 105 dB while average sound levels at entertainment venues range from 104 to 112 dB, exceeding permissible levels (80 dB for adults; 75 dB for children) even if for very short periods of time.The researchers wanted to gauge the prevalence of unsafe listening practices among teens and young adults to create a global estimate of the numbers who could therefore be at risk of hearing loss, with the aim of informing evidence-based policy to safeguard aural health.They trawled research databases for relevant studies published in English, French, Spanish and Russian, involving 12-34 year-olds, and reporting on objectively measured device output levels and length of exposure.The researchers also estimated the global number of people who could be at risk of hearing loss by considering the estimated global population of 12-34 year-olds in 2022 (2.8 billion) and the best estimates of exposure to unsafe listening practices from PLDs or loud entertainment venues derived from the systematic review.The researchers acknowledge some limitations to their findings, including the varied study design—a particular feature of the studies on entertainment venues—and the absence of standardized methodology."