The woman let out her breath, as if exhaling a cigarette.
Vocalizations are determined by physical structure as well as the action of the respiratory system muscles and the acts of inhaling or exhaling.
For example, cats meow when exhaling and will purr when both inhaling and exhaling, and this gives each vocalization its own unique sound.
Practice breathing by sitting comfortably in a dim, quiet place and focus on inhaling and exhaling without becoming sleepy.
You might be paying attention to slowing down your breath, breathing in to a count of four, holding for a count of two and exhaling to a count of six, for example (a great breath sequence for instant stress relief, by the way).
