Editing Scuba set (section)

===Diffuser===
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A diffuser is a component fitted over the exhaust outlet to break up the exhaled gas into bubbles small enough not to be seen above the surface the water, and make less noise (see [[acoustic signature]]). They are used in combat diving, to avoid detection by surface observers or by underwater [[hydrophone]]s, [[Naval mine|Underwater mine]] disposal operations conducted by [[clearance diver]]s, to make less noise,<ref name=CUMA /> to reduce the risk of detonating [[acoustic mine]]s, and in [[marine biology]], to avoid disruption of fish behavior.<ref name=aaus />

Designing an adequate diffuser for a [[Diving rebreather|rebreather]] is much easier than for [[open-circuit scuba]], as the gas flow rate is generally much lower.{{citation needed|date=March 2017}} An open-circuit diffuser system called the "scuba [[muffler]]" was prototyped by [[Eddie Paul]] in the early 1990s for underwater photographers [[John McKenney]] and [[Marty Snyderman]]; the prototype had two large filter stones mounted on the back of the cylinder with a hose connected to the exhaust ports of the [[Diving regulator#Demand valve|second-stage regulator]]. The filter stones were mounted on a hinged arm to float {{convert|1|to|2|ft|cm|sigfig=1}} above the diver, to set up a depth-pressure-differential suction effect to counteract the extra exhalation pressure needed to breathe out through the diffuser. The scuba muffler was claimed to cut the exhalation noise by 90%.<ref name="ep2007" /> [[Closed circuit rebreather]]s proved more useful in letting divers get near sharks.<ref name="wo2006" />