Prof. Helmholtz on Vowel Sounds, 83 
elements of the compound sensation,—just as, for example, spe- 
cial methods of observation are requisite in order to convince 
ourselves that the apparent solidity of any object at which we 
look arises from the coalescence of different pictures presented 
to our two eyes. 
On this account I formerly proposed to designate by the name 
sound (Klang) the whole compound sensation produced by the 
motion of the air proceeding from a single sounding body, and 
to limit the name noée (Ton) to the simple sensation produced 
by a simple pendulum-like motion of the air. Accordingly the 
sensation of a sound is generally composed of the sensations 
of several simple notes. If we limit to sounds all that Seebeck 
said in his discussion with Ohm, and to notes the assertions of 
Ohm, both these distinguished acousticians are right, and the 
assertions of both may remain undisturbed side by side. 
We will retain this designation throughout, and at the same 
time agree to understand by the pitch of a sound the pitch of 
the gravest simple note of n oscillations contained therein, 2. e. 
the pitch of its fundamental or primary note; all others will be 
called incidental or higher notes. I call the note of 2n oscilla- 
tions, the octave of the foregoing, the second note; that of 3n 
oscillations the third note, and so on. 
The generosity of His Majesty the King of Bavaria having 
enabled me to procure the apparatus necessary for my research, 
I proposed to examine the consequences of the proposition of 
Ohm on the theory of tones (K/angfarbe). In a physical point 
of view, it has long been known that the different forms of the 
aérial waves within each single period of oscillation correspond 
to what our ear distinguishes as different tones or qualities of 
sound. But this hypothesis rested solely upon the fact that 
there was no other possible way of explaining such differences 
of tone. An experimental verification was requisite, and this is,, 
perhaps, now supplied by my researches. 
In a physiological point of view, a further consequence 
could be drawn from the proposition of Ohm. Since all oscil- 
lations which do not correspond to the simple motion of a 
pendulum produce sensations in which a certain number of 
simple notes are distinguishable, sounds of different qualities 
whose primary notes have equal pitch, must, to the ear, be 
rendered different by the different intensities of the harmonic 
incidental notes. Let us leave out of consideration the different 
ways in which sounds of different instruments and voices com- 
mence and cease, as also the manifold shouting, grating, jarring, 
irregular noises which accompany many of them, and which, 
properly speaking, ought not to be considered as constituting the 
musical part of the sounds, and let us call the part of the tone 
G2 
