Breath and sound go hand in hand. Deep, resonant, low-register notes can transform your orgasmic abilities. They open up the body cavity because the mouth is usually pretty wide open and the energy flow gets much more accentuated. Sound and breath can lead to multiple orgasms.
Making noise during sexual play is a turn-on and helps us know where our partner is in the sexual response cycle. The signs of arousal and stimulation, especially in women, are very hard to interpret even with sound added. When we open up our mouths to let sound out, we literally open up the body cavity and allow the energy and pleasure to be transported through us.
It's almost physically impossible to make deep sounds while in orgasm and hold your pelvic region tight at the same time. Moaning opens up the pelvic region and relaxes the genital area, greatly enhancing the full-body orgasms that follow.
If making sounds is new for you, let your partner know that you'd like to try it. It can even feel a little silly at first, but being vulnerable will draw you and your partner closer, so go for it. Consciously bring sound to your lovemaking so you can really see how it works.