Start by making a humming sound. Vibrate your voice box and expel the air coming out of your lungs through your nose.
Lower the tone of your hum until you have reached a tone similar to a bass sound. Tighten your voice box while continuing to hum, and notice how the tone lowers itself in pitch.
Create the attack sound of the bass. Say the word "Tim" and start humming on the letter "m." Attack is the first part of an electric bass sound that is heard, which gives it its punch. Repeat the entire process until you have perfected the throat bass sound.