It is for this reason that the sounds of nature tend to produce trance. The type of variations within the TGL determine to a great degree the effectiveness and depth of the trance. When there is some 'subtilty' or artistry in the creation and modulation of the DTP, then the trance is compelling and there is an increase in the trance force. A loud, heavy beat is not necessary. Loudness or heavyness is not of itself productive of trance.
Repetition produces trance.
But it will be the type of repetition which is 'engaging' or which produces an involvement with the inner reality. Subtle loops tend to bring the attention to a finer focus. The resulting splitting or dissociation results in trance. But that is not the whole story. What 'subtle' is to one person may be different for another.