Ujjayi breath is also called ocean breath and victorious breath; there is a sound to it. It sounds like waves of the ocean. It is a form of pranayama, conscious breathing. It is commonly practiced while doing asana, the physical postures of yoga. This type of breathing is useful because when it is done correctly it helps you to assess the quality of your breath. You can hear if your breathing becomes jagged and laboured, or if the sound of your breath is steady. It supports slowing down your breathing, which allows you to breathe more deeply.
Prana is life force. Healthy life force is energetic and lively. When we think of where we get our energy, we habitually think of food. Sometimes we might think of water. When I started to take my yoga practice earnestly, I chose to practice hot yoga. This is mostly physical postures which we call asana practice and it is done in a sauna. It is physically challenging. In the primary stages I felt tired, I thought if I would eat more I would gain more strength. I ended up realizing my weakness was due to shallow breathing. As I concentrated more on my breath and started to practice ujjayi breath, I found I sustained the strength I needed to do the physical postures.
To practice ujjayi, you must become familiar with the epiglottis. The epiglottis is a piece of cartilage in your throat. You typically use your epiglottis when you sigh or breathe in a way that fogs up a mirror. Or you can find your epiglottis by breathing slowly and noticing where you feel the breath in your throat. Now try close off that area and breathe in and out. It is not a strong contraction, and you will not be making a very loud noise. Only loud enough that you can hear. You are using this breath as a tool for yourself, not to impress others with how loud you can breathe. The yoga teacher may perform this loudly, but they are only doing this to remind the class that they need to be breathing.
During final rest or savasana we allow our breathing to become relaxed, and we cease our ujjayi breath. While practicing asana, the physical postures of yoga, ujjayi breath is recommended. Ujjayi practiced while doing asana will faithfully deliver you more strength allowing you to carry out work. Ujjayi breath can help prevent injuries. Without the sustainable practice of ujjayi breath, you will not know when you are pushing yourself too far into a posture.