Acoustic ecologist Gordon Hempton collects sounds from around the world. He’s recorded inside Sitka spruce logs in the Pacific Northwest, thunder in the Kalahari Desert, and dawn breaking across six continents. An attentive listener, he says silence is an endangered species on the verge of extinction. He defines real quiet as presence — not an absence of sound but an absence of noise. We take in the world through his ears. This interview is edited and produced with music and other features in the On Being episode "Gordon Hempton — Silence and the Presence of Everything." Find more at onbeing.org. This interview originally aired in May 2012.