It brings us together, it provides us with happiness, it voices our feelings—singing is beautiful, and its effect on characters in the The Red Tent is palpable.
While with Esau's family, for example, Dinah hears Esau's daughters sing, and it resonates with her physically: "Their song was unlike anything I'd ever heard, and the hair on the back of my neck stood on end, as though Joseph were tickling me with a stalk of grass" (2.4.58).
Dinah is struck by this singing so much that she actually has a bodily reaction to it. In a way, singing actually bypasses words and language; it's a way of communicating that goes beyond we can actually say to each other.
Dinah's not done, by the way. She's also got this to say about the singing she's heard: "They sang the words in unison, yet somehow created a web of sound with their voices. It was like hearing a piece of fabric woven with all the colors of a rainbow. I did not know that such beauty could be formed by the human mouth. I had never heard harmony before" (2.4.58).
Just as the words are sung in unison, the people who sing the words are bound together in unison. In other words, singing is a way of bringing people together in this book.
There's more, too. Singing, for example, is one way that Rachel soothes her patients. Just as Dinah feels the physical effect of singing, Rachel uses it as a way to ease the pain of birth: "It was not an herb or a tool, but a birth song, and the most soothing balm that Inna or Rachel had ever used. It made laboring women breathe easier and caused the skin to stretch rather than tear. It eased the worst pains" (2.6.46).
To wrap it up, singing is truly a meta kind of force in The Red Tent. It transcends what's normally possible in everyday communication. Whenever there's singing in this novel, there's bound to be some kind of physical and emotional binding or release.