Thanks to all for your quick responses to my previous question.
Another question. I'm not sure how loud the hissing is supposed to be on exhalation during SBP. I assume there is no vocalization at all, but is it loud enough to be heard by someone next to me (like a cat's purr) or is it a hiss that is barely audible.
I don't think it matters how loud ujayi breathing is. It is more important that the throat is slightly closed so there is a slight pressure in the lungs with the out-breath. When I do it would just about be audible to someone sitting next to me. If ujayi is too strong then it could distract from the visualization process of Spinal Breathing which is quite a delicate internal process.