Every single day a Heavenly Voice emanates from Har Chorev
Our rabbis tell us that there is a constant humming present in the air near Har Sinai, suggesting an echo. The Tiferes Yisroel explains that this hum is a product of the powerful voice of Hashem which emanated at Har Sinai during the time of Matan Torah. It serves to remind us that the Torah was given in the presence of all the neshamos of Klal Yisroel that would ever be in the world, and we are obligated to heed the Torah throughout all the generations.
