A little more detail
The number of snoring events per hour of sleep (events per hour); it is usually measured during polysomnography with a microphone or a vibration sensor. Because the sound level from which snoring is counted differs from study to study, the numbers cannot be compared directly. In the 121-person study by Levartovsky and colleagues, the index was 23% higher in men and fell by about half over the night; snoring intensity, however, was not related to the AHI. In a meta-regression pooling 13 studies, snoring measures were generally strongly related to the AHI; however, the snoring index remained a weaker indicator than intensity and frequency measures.
Source: Levartovsky A, Dafna E, Zigel Y, Tarasiuk A. Breathing and snoring sound characteristics during sleep in adults. J Clin Sleep Med. 2016;12(3):375-384. doi:10.5664/jcsm.5588; Chiang JK, Lin YC, Lu CM, Kao YH. Correlation between snoring sounds and obstructive sleep apnea in adults: a meta-regression analysis. Sleep Sci. 2022;15(4):463-470. doi:10.5935/1984-0063.20220068