You do not need an echo effect added to a microphone, if you have a substantial size of the resonant space in your throat. This space is known as the pharyngeal cavity.
People who have their middle constrictor relaxed or less connective desmoplasia of soft tissue attaching the hyoid bone, can be classified as having natural resonant voice capabilities.
However, 99% people have their hyoid bone in that vicinity, which does not move very well.
If I massage the throat muscles and pull out (from the exterior) the hyoid bone while humming, the space of pharyngeal cavity can be made bigger.
The voice is made by vibrating air, echoing in 5 resonance chambers and then coming out from the mouth or nose. The sound and air which vibrates and travels then reaches to other people’s eardrums, thus other people being able to recognize the voice.
If you hum while pulling out the hyoid bone, even a small voice can echo very well. This is because the pharyngeal cavity has expanded. Even a slight expansion can be distinguished. This makes it possible to create a larger natural echo effect.
You can create a better echo in your voice by using this technique.
Note1:The thyroid cartilage and the stylohyoid muscle are suspended by the stylopharyngeus muscle, which are suspended in the air. If you have a problem with moving the cricothyroid articulation, you will notice it is hard to let out a high-pitched voice and that the hyoid bone will not move or shift well. The hyoid bone must shift well to make the space of the pharyngeal cavity bigger, therefor an echo effect can be produced as well as enhanced.