Let us now imagine this same critic to be listening to a singer, not an artist of the first rank, but one whose voice is marred by some slight faults of production. In this case the critic will note exactly the same sort of differences in tonal value as in the case of the violinist. Some of the singer's notes will be perfect musical tones, others will be marred by faults of intonation or of quality. But a great difference will be noted between faulty tones played on the violin, and faulty tones sung by the human voice. In addition to their blemishes as musical tones, the faulty notes of the voice also convey to the critical listener an idea of the state of the singer's throat in producing them. Every blemish on the beauty of a vocal tone, every fine shade of quality which detracts from its perfection, indicates to the critical hearer some faulty action of the singer's vocal organs. The more faulty the musical character of the singer's tones the more pronounced is this impression of faulty production. On the other hand, just so nearly as the singer's tones approach perfection as musical sounds, so do they also impress the ear of the critical listener as indicating the approach to the perfect vocal action. The critic could not impart to his untrained friend the impressions made by the violinist's tones. Somewhat the same is true of the impressions made by the tones of the voice on the critical ear. In voices of extremely nasal or throaty sound these blemishes can, of course, be detected by the ordinary hearer. But the fine shades of difference in vocal tone quality, heard by the trained critic, cannot be noted by the inexperienced listener. This fine ability to discriminate between musical sounds comes only through experience in listening to music, better still, when this has been combined with the actual study of music. But the ability to judge the vocal actions of singers, through the sympathetic sensations of tone, does not depend on any actual exercise of the listener's own voice. For the developing of this ability the exercise of the ear suffices. The mere exercise of the ear, in listening to singers, entails also the training of what may be called the "mental voice." Attentive listening to voices, involving as a natural consequence the sub-conscious impressions of sympathetic sensations, results in the development of a faculty to which this name, the mental voice, very aptly applies.