No tak tedy nevím, zdali je relevantní vykládat si normu, podle toho, co je napsáno na nějakém naslouchátku. Nejlepší je se přeci podívat přímo do té normy, kde se o IP57 píše toto: "Ingress of dust is not entirely prevented, but it must not enter in sufficient quantity to interfere with the satisfactory operation of the equipment; complete protection against contact. Ingress of water in harmful quantity shall not be possible when the enclosure is immersed in water under defined conditions of pressure and time (Test duration: 30 minutes - Immersion at depth of at least 1 m measured at bottom of device, and at least 15 cm measured at top of device.)."