Old sight, or presbyopia 215 32. Hearing and sound 215, 216, 217 33. The external ear 217, 218, 219 34. The middle ear 219-222 35. The internal ear 222, 223, 224 36. Protection of the sense of hearing 224, 225, 226 * * * * * {227} CHAPTER XI. THE VOICE. _Voice and Speech--The Larynx, or the Organ of the Voice--The Vocal Cords--The Laryngoscope--The Production of the Voice--The Use of the Tongue--The different Varieties of Voice--The Change of Voice--Its Compass--Purity of Tone--Ventriloquy._ [Sidenote: 1. The uttering of sounds by animals? How produced?] 1. VOICE AND SPEECH.--In common with the majority of the nobler animals, man possesses the power of uttering sounds, which are employed as a means of communication and expression. In man, these sounds constitute the voice; in the animals, they are designated as the cry. The song of the bird is a modification of its cry, which is rendered possible from the fact that its respiratory function is remarkably active. The sounds of the animals are generally, but not always, produced by means of their breathing organs. Among the insects, they are sometimes produced by the extremely rapid vibrations of the wings in the act of flight, as in the case of the musquito; or they are produced by the rubbing together of hard portions of the external covering of the body, as in the cricket. Almost all kinds of marine animals are voiceless. The tambour-fish and a few others have, however, the power of making a sort of noise in the water. [Sidenote: 2. The evidence of man's superior endowment? What is stated of the idiot? Parrot? Raven?] 2. But man alone possesses the faculty of speech, or the power to use articulate sounds in the expression of ideas, and in the communication of mind with mind. Speech is thus an evidence of the superior endowment of man, and involves the culture of the intellect. An idiot, while he {228} may have complete vocal organs and full power of uttering sounds or cries, is entirely incapable of speech; and, as a rule, the excellence of the language of any people will be found to be proportional to their development of brain. Man, however, is not the only being that has the power to form articulate sounds, for the parrot and the raven may also be taught to speak by rote; but man alone attaches meaning to the words and phrases he employs. [Sidenote: 3. Speech and hearing? A deaf child? Person having "no ear for music?" Impaired hearing? What do the examples show?]