Tom Pearson, from the US Agricultural Research Service in Kansas has developed a gadget that listens to the distinctive pings made by pistachio nuts when they bounce off a surface could help to sort open-shell nuts from uncrackable closed ones.

The sound-based “Pistachio Blaster” analyzes sounds made during and immediately after each nut strikes a polished stainless steel block.

Those sounds are captured as electrical signals by a microphone and sent to a computer that distinguishes the sound pattern made by the impact of a closed-shell pistachio from that of an open-shell nut, “much like your ear can distinguish a ‘plink’ from a ‘plunk,'” Pearson says. When the analysis reveals the telltale sounds of a closed-shell nut’s bounce, the computer sends a signal that causes a blast of compressed air to direct the nut to the reject bin.

Via New Scientist.
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