Singers are Silvers who can use their voice to control anyone as long as direct eye contact is established.
"Singers are perceptors, similar in ability to whispers in that they are able to manipulate or control the minds of others. However, singers are limited by the requirement of eye contact, and they cannot read thoughts as their whisper counterparts can. They are similarly mistrusted in the Lakelander society, but since they are fewer in number, the singer lines have escaped extermination in that country. In Norta, the noble singer dynasty, House Jacos, fell into near poverty before being elevated again by the marriage of Coriane Jacos to King Tiberias Calore VI. The queen died young, but mothered the current heir to the throne, Tiberias Calore VII." - On Silverblooded Abilities by Victoria Aveyard