Instrumental music can rev you up or chill you out. That goes double for instrumental metal: in the absence of vocals, artists explore dynamic extremes and stretch the emotional boundaries of their chosen genres. For proficient virtuosic shredders such as Steve Vai and Yngwie Malmsteen, or the adventurous progressive-rock band Animals As Leaders, such unfettered exploration helps explain why they’re so beloved and admired. The same goes for sprawling post-rock acts such as the cinematic Godspeed You! Black Emperor and the more aggressive Pelican, who push heavy music to dramatic new heights. But for bands that normally have vocalists, instrumental metal offers a chance to embrace a different side. Thrash legends Metallica sculpted an epic worthy of Greek mythology with “The Call of Ktulu”, while theatrical hard rockers Ghost, thundering drone metal icons Sunn O))) and alternative rockers Faith No More have offered satisfying sonic detours without saying a word.