YouTube user Mileán Ó Raghallaigh shot video of a man demonstrating a Death Whistle, an ancient Aztec instrument used to honor the deceased during Day of the Dead rituals and brought out in large numbers when entering battle. Multiplied by 100, it’s easy to imagine a downright terrifying sound.
And also they used [it] when they fight with other tribes. They played over 100 death whistles [while] marching and make a lot of noise to cause a big psychological effect to the enemy. So this is a very intimidating instrument.