Well, there are basically two techniques that one can adopt. These are undergoing a voice lowering surgery and knowing how to train your voice. The first option of getting a surgery done can be quite risky as you can end up getting your voice damaged. It is also a costly procedure which makes most people to refrain from it. Getting your voice trained is a more preferred choice for those who want to know how to make your voice deeper. This is a natural technique in which you can deepen your voice through proper training which makes it a part of your speaking habit.
Prior to learning how to make your voice deeper it becomes essential to understand the process of voice production. An organ known as Larynx functions to produce sound when you speak. This is the region which comprises of several folds known as vocal cords. These vocal cords happen to produce sound due to vibration. This usually varies depending on the length of your vocal folds and the tension within them. The tension is usually greater in male vocal cords as they are longer folds. This is the reason why males can sing in a low pitched voice compared to females whose voice is at a higher pitch.
When looking to learn how to make your voice deeper you must be able to lengthen the folds and thus reduce the tension. The Cricothyroid and the Vocalis muscles are responsible for such functions. Hence, the best technique to deepen the voice is to release the tension that exists in the vocal cords. These can be conditioned easily to relax and reverberate. Learning how to acquire control over these muscles will enable you dominate over your voice deliberately. Loosening up the vocal cords by repeatedly producing certain sounds and even working out such muscle groups will train your muscle to become familiar with the new amounts of tension. Once the muscles have been tuned to alter the vocal cords, lengthening the folds will become quite an easy task. This will eventually deepen your voice.