What does this stacked greater than less than symbol do to this equation

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I'm reading this paper

J. Sohn, N. S. Kim, and W. Sung. A statistical model-based voice activity detection. IEEE Signal Processing Lett., 6 (1): 1-3, 1999. doi: 10.1109/97.736233.

and I came across this equation. $$ \log{\bf\Lambda} = \frac{1}{L} \sum_{k=0}^{L-1}\log\Lambda_k \mathop{\lessgtr}_{H_0}^{H_1} \eta $$

I've not seen the stacked greater than and less than symbol. What does it mean? How does it affect the equation?