}}
The Penguin Guide to Jazz selected the album as part of its suggested Core Collection. The authors wrote: "What a vital, electrifying document this remains!... Mitchell organizes his group around the notion of sounds entering into - and interrelating with - silence. So there are tiny gestures and startling emptinesses alongside long lines and soliloquies... Both a manifesto and an unrepeatable event,
Sound remains a marvel." The
AllMusic review by Steve Huey awarded the album 5 stars, stating, "Structurally,
Sound heralded a whole new approach to free improvisation; where most previous free jazz prized an unrelenting fever pitch of emotion, Sound was full of wide-open spaces between instruments, an agreeably rambling pace in between the high-energy climaxes, and a more abstract quality to its solos. Steady rhythmic pulses were mostly discarded in favor of collective, spontaneous dialogues and novel textures (especially with the less orthodox instruments, which had tremendous potential for flat-out weird noises). Simply put, it's an exploration of pure sound." The album was identified by Chris Kelsey in his AllMusic essay "Free Jazz: A Subjective History" as one of the 20 Essential Free Jazz Albums.
Elliott Sharp called the album "one of Mitchell's finest early moments" and included it in his list "Ten Free Jazz Albums to Hear Before You Die". ==Influence==