Human vocal cord is like a wind instrument. Breathing is the key to sounding instrument. If the correct breathing techniques, experts say, then half of affairs are correct voice production as well.
There are three types of respiration: respiratory shoulders, chest breathing, and abdominal breathing. Classical vocal technique requires diaphragmatic breathing. Respiratory diaphragm is located between the chest cavity and abdominal cavity, absolute requirement singing is vocal cords and throat is flexible. Therefore, it needs to warm up and vocal exercises every time you train or before boarding stage. Training begins with a soft voice. Throat should not tense.
Vibra is actually happening when we are "sounding" voice. This caused a contraction in the vocal cords.
ring one note synthesizer from the keyboard, listen to his voice undulating, like that Vibrate and slowly try to follow. Until you can find your Vibrate sound natural. To practice: