What is the deep sound that buddhist monk make during meditation called I have often noticed buddhist monk make deep sound, something that feels might be coming from the naval or sometimes the throat. I want to know more details about the sound. What is the origin and if there is a specific name to it. Is it same as the "om" of Hinduism?
From https://en.m.wikipedia.org/wiki/Buddhist_chant


  Tibetan monks are noted for their skill at throat-singing, a specialized form of chanting in which, by amplifying the voice's upper partials, the chanter can produce multiple distinct pitches simultaneously. Japanese esoteric practitioners also practice a form of chanting called shomyo.


From https://en.m.wikipedia.org/wiki/Overtone_singing#Tibet


  Tibetan Buddhist chanting is a subgenre of throat singing, mainly practiced by monks of Tibet, including Qinghai (Khokhonor) province in the Tibetan plateau area, Tibetan monks of Nepal, Bhutan, India, and various locations in the Himalayan region. Most often the chants hold to the lower pitches possible in throat singing. Various ceremonies and prayers call for throat singing in Tibetan Buddhism, often with more than one monk chanting at a time. There are different Tibetan throat singing styles, such as Gyuke (Tibetan: རྒྱུད་སྐད་, Wylie: rgyud skad) – this style uses the lowest pitch of voice; Dzoke (Tibetan: མཛོ་སྐད་, Wylie: mdzo skad), and Gyer (Tibetan: གྱེར་, Wylie: gyer).