Sounders

The sounders are an elite division within the already prestigious company of the Hammers of Moradin. They specialize in fighting in the dark, using their voices and hearing both for navigation and as weapons against their enemy
Despite the relatively good darkvision capabilities of dwarves the deep roots of the mountains are filled with a darkness that even the keenest eyes cannot pierce or most lightsources cannot pierce. Such caverns are known as lightdrinkers and, while the instinct of most would be to leave such places well enough alone, the dwarves also found that these caverns often indicate the presence of valuable minerals and metals. However, those that attempted to mine such places also found that the caves were home to all manner of evil creatures and additionally made for excellent ambush places during intra-clan warfare.
For this reason the Sounders were formed. They are an elite division of dwarves who choose to go through life blindfolded using only their hearing and voices for navigating the world. At a young age they are inducted and blindfolded and they then never remove the blindfold except during certain ceremonies. They then go through rigorous training, improving their hearing and teaching them control over their voice. When they are deemed to be ready they learn magical techniques that allow them to amplify their voice. At first this process simply lets them use the echo of their voice to "see" further than before. As their magical prowess increases the volume and directionality they can achieve effectively weaponizes their voices, giving them, among other things, the ability to stun their enemies.
Those Sounders who achieved the greatest prowess did not even need to produce sounds themselves to map out the space around them. The measest tinkling or sound of breathing was sufficient for them to "see" and therefore they became highly prized both as bodyguards and assassins.
The Sounders division has proven to be extremely efficient, both for helping to map the networks of natural tunnels the dwarves encountered, clearing out lightdrinker caverns, and for covert operations both within the Dwarven Empire and outside its borders.