Voice is under the umbrella of speech. It is simply the sound that one refers to - not the language (words), not the articulation of sounds- but the sound that comes out when one speaks. There are several subsystems of the voice; respiration, phonation, resonance.
Respiration: Our breathing. VITAL to voice production. Sometimes our breathing patterns can become disrupted with a voice disorder. You may develop patterns of “breath holding” during speech to either work harder to get sound out or to prevent too much air from escaping through the vocal folds. Breath patterns may become shallow, with more tension in the neck, shoulders, or neck, rather than full easy breaths of air. Breath may become “choppy” with speech in an individual with SD, tremor, or with Muscle Tension Dysphonia. One may use too little airflow for speech, causing a rough or strained vocal quality, occasionally with the sensation of more effort during speech. Sometimes addressing these breathing patterns will be of help for someone with a voice disorder.
Phonation: When we make attempts to make sound, or voice, the brain signals the muscles that control our vocal folds (aka vocal cords) to bring the vocal folds together, air passes through our vocal folds and this air makes them vibrate in a periodic, or regular, fashion. This vibration with the airflow flowing through the vocal folds creates sound. The sound is then carried through the throat (pharynx) and mouth (oral cavity) where it “resonates” to create different sound qualities.
Resonation: How the sound that is created at the vocal folds vibrates in different cavities (i.e. pharynx, nose, mouth). Different shapes of the vocal tract and the mouth can create different vocal qualities (i.e. rough, strained, or clear voice). You can use certain voice techniques to create efficient vocal tract configurations to shape sound -to make a rougher voice sound clearer and a strained voice feel easier (this is one thing that voice therapy capitalizes on).
Articulation: How we shape our voice into speech sounds (vowels and consonants) using our tongue and lips. Once the sound is vibrating and we have voice, it is shaped into different sounds and words (aka speech!) with our tongue and lips, which is called articulation.
What is the difference between voice, speech, and language?
Speech is the result of physical subsystems of respiration, phonation, resonance, and articulation discussed above. It is an umbrella term that includes voice. Language involves stringing together words to form meaningful sentences, or the ability to understand words that have meaning.