Whether a professional singer or a singer for hobby, if you are developing a professional voice you should have a goal for maximum output with minimal effort. Acoustic output should be easily attained with very little physiological effort, so why do we feel like we have to push to get some sounds?
Source-Filter Theory should begin the discussion. You ask yourself, "Where did I learn about that first? Was it just something I memorized for a test?" It's actually quite easy to explain and the actions are in the name. Remembering that you have a source of sound (your vocal fold vibrations) and that the sound is modified by the filter of your vocal tract is all you have to know. The shape of your throat and mouth take the sound signal and dampen some formants and amplify others, creating your unique sound.
Think of your singing as training the intrinsic muscles of the larynx to strengthen your chest voice. This does not mean that you will always need to sing in your chest voice, but it is important to have control of your whole range, low and high, to master using each when appropriate. There is also the issue of correctly defining chest/belt and head/falsetto voice. I was at a conference at UTSW last month where Dr. Stephen F. Austin spoke regarding this issue. As a singer, you have to remember that your vocal cords or folds are not the only things working in your throat to make sound. He reminded the audience that firm phonation is a full contact sport, furthering the image that one must really commit to working out the voice muscles daily, as any athlete would, to avoid injury and have the best and most efficient working mechanism.
Chest voice can be created by increasing motor signals to the thyroarytenoid muscles (vocal folds). As the vocal folds contract, they bulge toward the middle (medially) and down (inferioraly). If you exercise your TA muscle, it will respond to the exercise because it is a skeletal muscle. Your aim is for creating a square glottis when you have phonation, or vocal fold vibration. With a larger area of contact during vibration comes a stronger sound.
Falsetto, or head voice, is created by decreasing the engagement of the thyroiarytenoid muscles, or the vocal folds. At the same time, you increase the cricothyroid and lateral crycoarytenoid muscles. When beginning your singing training, make sure there is a strong enough chest voice to have an audible break into falsetto. Once this is established, work begins on smoothing out between registers.
Yodeling, interestingly enough, is transitioning between the two types of voice very quickly. One has to relax the larynx enough to perform the switch to each octave along with coordinating the articulators (lips, teeth and tongue) to sprinkle /l/ and /d/ throughout different vowels.
Chest voice is always a "dangerous" subject, as most vocal training programs are tailored for classical singing. Dangerous because it is like the plague and no one wants to touch it. Reality is, though, chest and belting voice is the most common vocal style in contemporary commercial music (CCM). That means most people with singing careers don't have formal training, but can have real problems that need an experienced teacher. Leborgne and Rosenberg state that 34% of university level teachers who train non-classical singers have never been trained in commercial music. So, why are we putting singers at risk by not being well trained in both classical and contemporary styles of singing? Just with chest singing, falsetto voice can be abused if not trained properly, so it is important to learn to do each the proper way to avoid injury.
So don't let belting and chest voice singing stress you out. Just like falsetto singing, belting and chest voice singing needs to be taught correctly to avoid injury to the vocal mechanism. Remember, registration is a choice and with proper practice in each, you can keep an efficient larynx in good working order. Dr. Austin reminds us that everything we do can't be beautiful, we must experiment with our instruments.
References: Lecture by Dr. Stephen F. Austin at UTSW Singers Symposium 2015
The Vocal Athlete. Ronenberg, Marci & Leborgne, Wendy D. Plural Publishing 2014.
Kristie Knickerbocker, MS, CCC-SLP, is a speech-language pathologist and singing voice specialist in Fort Worth, Texas. She rehabilitates voice and swallowing at her private practice, a tempo Voice Center, and lectures on vocal health to area choirs and students. She also owns and runs a mobile videostroboscopy and FEES company, Voice Diagnostix. She is an affiliate of ASHA Special Interest Group 3, Voice and Voice Disorders, and a member of the National Association of Teachers of Singing and the Pan-American Vocology Association. Knickerbocker blogs on her website at www.atempovoicecenter.com. She has developed a line of kid and adult-friendly therapy materials specifically for voice on TPT or her website. Follow her on Pinterest, on Twitter and Instagram or like her on Facebook.