Stretch your vocal cords with a vocal warm-up technique. Use the major singing scale made of seven basic notes: Doh Re Mi Fa So La Ti.
Sing each note in the scale starting with a low note and gradually work up to the high note at the end. The ending note should be vocalized as Doh in the next note up from Ti. Then sing the scale backward from the high note gradually working down to the low note you began with. Repeat until your voice is stable with no cracking.
Play, or have a musician play, the key middle C. Notes should be played downward as you sing every note until you can no longer produce a clear sound that matches the instrument.
Play, or have your musician play, that last note again and work the notes upward as you sing each note until you reach the note that you can sing clear and stable, and sustain with ease and comfort. Record this note; it is the lowest you can sing, also known as the lower boundary of your vocal range.
Play the key middle C again. This time notes should be played upward as you sing every note until you can no longer produce a clear sound that matches the instrument.
Play that last note again and work the notes downward as you sing each note until you reach the note that you can sing clear and stable, and sustain with ease and comfort. Record this note; it is the highest you can sing, also known as the upper boundary of your vocal range.
Count the number of octaves between your upper and lower voice limits to determine your full range.
Determine in what octave you sounded the best and were most comfortable singing. This is your note in voice.