Most of us can’t bear the sound of nails on a chalkboard (shudder), but now, researchers have a possible explanation as to why the sound makes us cringe and cover our ears.

It turns out our adverse reaction to the piercing sound is partly physical and partly psychological, and that the part of the noise that makes us wince has a frequency between 2,000 and 4,000 Hz (hertz), a range naturally amplified by the shape of our ear canals, Wired Science explains.