The role of SOUND in SURVIVAL and/or martial arts, has beensomewhat ignored in favor of other devices and signals, such as, flares, fires, lights,semaphor, flags, cell phones, compasses, and GPS not to mention other reliance on visual 'clues and cues' or visual preferences which exclude for the most part all the other senses. The dependence on electronic things especially including radios, mirrors, flashlights, torches smoke signals, analog and digital watches and other instruments all come ot mind.
But, SHOUTS, ECHOS,WHISTLES, HORNS, and other noise makers, even firecrackers, STRATEGICALLY TRANSMITTED along NATURAL SOUNDING BOARDS or FORMATIONS & SOUND CARRIERS are often overlooked. Also, these will carry sounds, to the enemy if approaches involve noice or sound and little silence, such as, talkling or foot vibrations.
The old 'ears to the ground' or against a railroad track or on a concrete/tarred highway or road can often dettect vibrations of approaching people, vehicles, trains, animals and armies,etc.
SOPHISTICATED T ECHNOLOGICAL COMMUNICATIONS are NOT a guarantee of SURVIVAL in hostile or even friendly environments.
Industrial and transportational systems once powerful & popular and prevalent are no longer in existence in many parts of the world and those that are now in existence are crumbling and in dire need of repair. So-called infrastructure, like roads, b idges, ports and airfields are are often in need of improvement and redesign .
At any rate, teh role of sound and VIBRATION is important for study by martial artists who wish to survive in every conceivable environment, perhaps even in 'outer space'.