Some people are never happy with the way they sound when recorded. However, singers, narrators and voice-over artists have to quickly get over this fear. Experience in those industries quickly yields a secret. Skilled artists can use the microphone to their advantage and use a combination of practice and technique to deepen the sound of the voice. This can be coupled with post-production techniques to create a final audio that is much lower than what you might naturally sound like.
Warm up your voice properly. Take singing lessons or work with an acting coach to learn how to do this. Concentrate on breathing into your abdomen and relaxing your jaw, throat and soft palate. Stay relaxed as you speak or sing and your voice should naturally drop in and start to sound deeper.
Use a mic that has a good proximity effect. Opt for mics that are designed for vocal use, as these often provide strong proximity effects.
Position your mouth very close to the microphone. Get as close as you can without your plosives popping on the track. Use a pop filter to help reduce plosive impact even when very close to the mic.
Hold the mic loosely if you are holding it in your hand for a live performance versus recording in a studio. If you grip it too tightly, you can limit your ability to sound low on the vocal.
Process the mix correctly in order to emphasize the low end of your voice when working in a recording environment. Apply an equalizer effect to the track and boost the lower end frequencies. Monitor the changes carefully, though, so that you don't end up with a voice that sounds artificially processed. Subtle shifts are all that is needed to bring out the low end.
Long-term vocal work can allow you to lower your voice naturally. Deep breathing exercises and tone placement can help you lower the pitch of your voice several semi-tones, but working with a qualified vocal coach is almost always required to achieve this sort of effect. Joaquin Phoenix employed this effect to lower his voice enough to play famous country singer Johnny Cash in "Walk the Line."