PEKCEPTION OF QUALITY. 813 



sound-conducting apparatus generally is increased. (2) By elimination of the sound-conducting 

 apparatus of the middle ear, which offers greater or less resistance to the propagation of very 

 high notes, as perforation of the membrane tympani, or loss of the incus and malleus. In these 

 cases, the stapes is directly set in vibration by the sound-waves, when tones up to 80,000 vibra- 

 tions have been perceived. Diminished tension of the sound-conducting apparatus causes 

 diminution of the perception for high tones {Blake). 



A smaller number of vibrations than 16 per second (as in the organ) are no longer heard as a 

 tone, but as single dull impulses. The tones that are produced beyond the highest audible 

 note, as by stroking small tuning-forks with a violin bow, are also no longer heard as tones, 

 but they cause a painful cutting kind of impression in the ear. In the musical scale the range 

 is, approximately, from C of the first octave with 16*5 vibrations to e, the eighth octave. 



Comparison of Ear and Eye. In comparing the perception of the eye with that of the ear, 

 we see at once that the range of accommodation of the ear is much greater. Red has 456 billions 

 of vibrations per second, while the visible violet has but 667, so that the eye only takes cognis- 

 ance of vibrations which do not form even one octave. 



Lowest Audible Tone. As to the smallest number of successive vibrations which 

 the ear can perceive as a sensation of tone, Savart and Pfaundler considered that 

 two would suffice. If, however, we exclude in our experiments the possibility of 

 the occurrence of overtones, 4 to 8 (Mach) or even 1 6 to 20 vibrations (F. Auerbach, 

 Kohlrausch) are necessary to produce a characteristic tone. 



When tones succeed each other rapidly, they are still perceived as distinct, when 

 at least 0'1 second intervenes between two successive tones (v. Helmholtz) ; if they 

 follow each other more rapidly, they fuse with each other, although a short-time 

 interval is sufficient for many musical tones. 



By the term, "fineness of the ear" or, as we say, a " good ear," is meant the 

 capacity of distinguishing from each other, as different, two tones of nearly the 

 same number of vibrations*. This power can be greatly increased by practice, so 

 that musicians can distinguish tones that differ in pitch by only 3 Jq, or even 

 two> f their vibrations. 



With regard to the time-sense, it is found that beats are more precisely perceived 

 by the ear than by the other sense-organs (Hbring, Mack). 



Pathological. According to Lucae, there are some ears that are better adapted for hearing 

 low notes and others for high notes. Both conditions are disadvantageous for hearing speech. 

 Those who hear low notes best hear the highest consonants imperfectly. The low notes are 

 heard abnormally loud in rheumatic facial paralysis, while the high tones are heard abnormally 

 loud in cases of loss of the membrana tympani, incus, and malleus. The stapedius is in full 

 action, whereby the highest tones are heard louder at the expense of the lower notes. Many 

 persons with normal hearing hear a tone higher with one ear than with the other. This con- 

 dition is called diplacusis binauralis. In rare cases, sudden loss of the perception of certain 

 tones has been observed, e.g., the bass-deafness of Moos. In a case described by Magnus, the 

 tones d', b 1 , were not heard ( 316). 



II. Perception of the Intensity of Tone. The intensity of a tone depends upon the ampli- 

 tude of the vibrations of the sounding body. The intensity of the tone is proportional to the 

 square of the amplitude of vibration of the sounding body, i.e., with 2, 3, or 4 times the ampli- 

 tude the intensity of the tone is 4, 9, 16 times as strong. As sonorous vibrations are com- 

 municated to our ears by the wave-movements of the air, it is evident that the tones must 

 become less and less intense the further we are from the source of the sound. The intensity of 

 the sound is inversely proportional to the square of the distance of the source of the sound from 

 the ear. 



Tests. 1. Place a watch horizontally near the ear, and test how close it may be brought to 

 the ear, and also how far it may be removed, and still its sounds be heard. Measure the dis- 

 tance. 2. Itard uses a small hammer suspended like a pendulum, and allowed to fall upon a 

 hard surface. 3. Balls of different Weights are allowed to fall from varying heights upon a plate. 

 In this case the intensity of the sound is proportional to the product of the weight of the ball 

 into the height it falls. 



As to the limits of the perception of the intensity of a tone, it is found that a spherule weigh- 

 ing 1 milligram, and falling from a height of 1 mm. upon a glass plate, is heard, at a distance 

 of 5 centimetres (Schafhault). 



415. PERCEPTION OF QUALITY VOWELS. By the term quality ("Klangfarbe "), 

 musical colour or timbre, is understood a peculiar character of the tone, by which it can be 

 distinguished apart from its pitch and intensity. Thus, a flute, horn, violin, and the human 

 voice may all sound the same note with equal intensity, and yet all the four are distinguished 



