When projecting your voice, especially when you sing, you're unconsciously utilizing one of the fundamentals of sound. "All sound is vibration," opera singer Matthan Ring Black told us on the Curiosity Podcast.

Especially when singing, "you have a system of breathing and positioning your body that allows your vocal folds to vibrate unencumbered, in a way that uses your entire body as a resonating chamber and then projects sound." Using opera singing as an example, Black explained that "vibration moves through all of your bones, all of your sinews, all of your tendons, rattles around in your chest and in your head, and then comes out through some sort of acoustical magic to make a beautiful sound."

The loudness of your speech or singing is determined by the force of the air passing between your vocal cords. What we typically call the diaphragm, or our "support system," is the power source for singing. "Breath is everything to a singer," Black said. "Singing does not exist without breath and without air."

We all breathe, so how hard can it be to breathe correctly? Harder than you might think. The principal muscles that help us breathe in are the diaphragm, but the diaphragm is largely impacted by the muscles around it. These muscles either raise abdominal pressure, forcing the diaphragm upward, or lower the ribs and breast bone, thereby compressing air in the chest. The chest and back muscles are also involved. And since all of these muscle groups can change the way you sound, it's important to have control over all of them – which can be quite a challenge.

"Because our instrument is our body, our emotions affect the way that [breathing] mechanism functions," Black explained. "So if you're scared, your stomach tightens up, your shoulders come in... we sort of scrunch our whole body together. That is the absolute worst body posture for singing. It doesn't allow your air flow to move easily, so if you're nervous about singing, then you're going to sing worse."

Soprano Sara Antunovich wrote on Quora that the problem extends much further than your air supply: "muscle tension anywhere, even tense legs, are a problem. Tension uses more oxygen, which leads to breathing problems and stress reactions." Learning what causes tension and how to relieve it are fundamental lessons in the world of vocal pedagogy, and can take a lifetime of training to master.

The characteristics and the volume of the sound that your voice produces depend on how different spaces in your body resonate with the sound waves created by your vocal chords. You can influence the way you sound by adjusting the position of your soft palate, your tongue, your larynx, and your diaphragm's support system. With all those variables, where does a person begin? For an opera singer, the answer is simple.

"You practice very slowly, and you have to dedicate your life to it," Black told us. And it never hurts to ask for help. "It's important when you're practicing and you're evaluating your own sound that you have people that you trust to help you. That's why we use really talented voice teachers and coaches, even after 20 years of practicing." This is because it's hard to evaluate your own voice objectively, due to – surprise, surprise – vibrations.

"The reason your voice sounds different to you than it sounds to someone else or to a microphone is because of the way the sounds are conducted," Black explained. "I'm hearing the vibrations of my own voice conducted through my bones. You know how your eardrum is made up of a bunch of tiny bones that vibrate and then turn the vibrations into sounds that you can understand? Rather than the sound leaving my mouth, bouncing around the room we're in, and then coming back through the air, the bones of my jaw and the bones of my neck – all the bones are connected to the little bones in your ears, so you're hearing the vibrations from the inside and the outside."

Over time, opera singers actually develop a muscle memory and learn to sing more from the way their body feels than from the way they sound. "It's probably like the way an Olympic gymnast doesn't practice by the way they look, because they can't see themselves; they have to practice their routines by the way that it feels, knowing that someone else is helping to guide and direct them there."

Pop singers, on the other hand, often have it easy, in comparison. "They have the microphone," Antunovich said. "Tight throats and jaws are very common. They don't need nearly as much support, so I don't know if they even think about their bodies as an opera singer does which is as an athlete; their bodies can remain loose or tight since the microphone is doing the work of projecting their sound."

While you're mastering your technique, you should also probably be aware of one more thing: the "singer's formant." Have you ever wondered why an opera singer can be heard over a much louder orchestra? Many singers mistakenly "yell" instead of singing when they want to project their voice, but that produces an unbalanced and harsh vocal resonance. There is a special technique that allows you to shape your throat in a way that produces a few "extra" frequencies when you sing, and that extra frequency – the singer's formant – cuts through other sounds.

For an opera singer to project over an orchestra, then, the goal is to maximize their sound output at frequencies above 2,000 Hz. This is because the orchestra produces lots of energy at around 500 Hz, but falls off steadily at higher frequencies, producing relatively little around 3000 Hz. "The voice can live and project and cut through all the other sound" within the singer's formant, Black told us. And that's where all that practicing comes in.

To learn more about the science of singing, vocal pedagogy, and the world of opera, listen to our conversation with Matthan Ring Black on the Curiosity Podcast. Stream or download the podcast using the player below, or find the episode everywhere podcasts are found, including iTunes, Stitcher, and Gretta.