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Here we investigate the pH-induced physical perturbation of a lipid interface and the physicochemical nature of the subsequent acoustic propagation. Pulses are stimulated by local acidification and propagate \u2013 in analogy to sound \u2013 at velocities controlled by the interface\u2019s compressibility. With transient local pH changes of 0.6 directly observed at the interface and velocities up to 1.4\u2009m\/s this represents hitherto the fastest protonic communication observed. Furthermore simultaneously propagating mechanical and electrical changes in the lipid interface are detected, exposing the thermodynamic nature of these pulses. Finally, these pulses are excitable only beyond a threshold for protonation, determined by the pK<jats:sub>a<\/jats:sub> of the lipid head groups. This protonation-transition plus the existence of an enzymatic pH-optimum offer a physical basis for intra- and intercellular signaling via sound waves at interfaces, where not molecular structure and mechano-enyzmatic couplings, but interface thermodynamics and thermodynamic transitions are the origin of the observations.<\/jats:p>","DOI":"10.1038\/srep22874","type":"journal-article","created":{"date-parts":[[2016,5,24]],"date-time":"2016-05-24T17:03:36Z","timestamp":1464109416000},"update-policy":"https:\/\/doi.org\/10.1007\/springer_crossmark_policy","source":"Crossref","is-referenced-by-count":37,"title":["Protons at the speed of sound: Predicting specific biological signaling from physics"],"prefix":"10.1038","volume":"6","author":[{"given":"Bernhard","family":"Fichtl","sequence":"first","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Shamit","family":"Shrivastava","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Matthias F.","family":"Schneider","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"297","published-online":{"date-parts":[[2016,5,24]]},"reference":[{"key":"BFsrep22874_CR1","unstructured":"Alberts, B. & Wilson, J. 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