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A Wonsul body barrels into them. Another appears by Krissana and Orfea. His head has been pulverized, mouth split and one eye caved in, skull barely holding together by a thin reinforcement mesh: an occipital segment is missing. The rest of him is in no better shape, though by miracle he’s kept all his limbs. “Benzaiten,” he says. “You were never going to come forth under duress. That wouldn’t have been like you. But please—” The acoustics of his throat crack and gutter. “Do it for love. One last time, let me hear your voice.”
Within the context above what does the expression gutter mean? I couldn't get it from some English dictionaries. Could anyone explain that of a way I can get that well?