This is an image from Lotte Lehmann’s 1902 singing book “How to Sing” showing sensations that certain pitches create in the body in soprano and tenor singers. In speech we don’t always get the air up to the roof of the mouth, but in singing, or to increase resonance in the speaking voice, it is a must! The roof of the mouth domes up like a cathedral and is the major resonating chamber for the voice. The air hitting the hard and soft palate in the roof of the mouth create vibrations in the body that a singer becomes aware of to insure a beautiful tone. As one sings up the scale air pressure increases in the mouth, causing the sound to hit different places on the hard and soft palate, creating sensations that the sound wave of the voice is traveling in a specific direction through the skull. Put your thumb in your mouth on the front of the hard palate on the roof of your mouth and hum a low tone. Feel the whole surface of the hard palate vibrate with sound. As you sing higher up the scale the sound will move backward on the hard palate and end on the soft palate. Notice what pitches correspond to a shift in sensation in the skull in your voice.  Lotte Lehmann’s chart was extremely detailed and your particular voice may experience vibrations slightly different, but there will always be the tendency for the vibrations of the voice to feel as if they are shifting up the face as pitch increases. The correct sensation of sound and vibration in the skull affects the tone.  If you try to sing a high tone but don’t raise the vibrating focal point, it will often be dull and flat. Play with this chart and see what sensations you can discover.