When the fork is struck, the ear hears the sound issuing from the resonator, not that coming direct from the fork. This is brought out distinctly by placing the fork at a little distance from the resonator. The listener can then definitely locate the source of the sound which impresses the ear. Under these circumstances the sound coming from the resonator is found to be many times more powerful than that coming direct from the tuning fork. If left to its own judgment the ear takes the resonator to be the original source of the sound. In the voice the exciting cause of the air vibrations is located at the back of the resonator,--the mouth-pharynx cavity. The sound waves in this case can issue only from the front of the resonator,--the singer's mouth. No matter how the voice is produced, correctly or badly, this acoustic principle must apply. Why then does not the incorrectly used voice impress the hearer as issuing directly from the mouth, the same as the correctly produced tone? This is purely a matter of sympathetic sensations of throat tightness, awakened by the faulty tone. Every wrongly used voice arouses in the listener sympathetic sensations of throat contraction. This impression of throat, noted by the hearer, consists of muscular, not of strictly auditory sensations. As a statement of scientific fact, the forward-tone precept is erroneous. It does not describe scientifically the difference between correct and incorrect tone-production. Correctly sung tones are not produced at the lips. Every vocal tone, good or bad, is produced by the motion of the vocal cords and reinforced by the resonance of the mouth-pharynx cavity. Only when considered as an empirical description is the forward-tone precept of value. In this sense the precept describes accurately the difference in the impressions made on the hearer by correct and incorrect singing. A badly produced tone seems to be caught in the singer's throat; the correctly used voice is free from this fault, and is therefore heard to issue directly from the singer's mouth. This marked difference between correct and incorrect tone throws a valuable light on the meaning of the correct vocal action. Every badly used voice gives the impression of wrong or unnecessary tightness, stiffening, and contraction of the throat. When perfectly used, the voice does not convey any such impression of throat stiffness. _The Open Throat_