We have hitherto examined the effect of sounding together only two tones which form a determinate interval. It is now easy to discover what will happen when more than two tones are combined. The simultaneous production of more than two separate compound tones is called a chord. We will first examine the harmoniousness of chords in the same sense as we examined the harmoniousness of any two tones sounded together. That is, we shall in this section deal exclusively with the isolated effect of the chord in question, quite independently of any musical connection, mode, key, modulation, and so on. The first problem is to determine under what conditions chords are consonant, in which case they are termed concords. It is quite clear that the first condition of a concord is that each tone of it should form a consonance with each of the other tones; for if any two tones formed a dissonance, beats would arise destroying the tunefulness of the chord. Concords of three tones are readily found by taking two consonant intervals to any one fundamental tone as \(c\), and then seeing whether the new third interval between the two new tones, which is thus produced, is also consonant. If this is the case each one of the three tones forms a consonant interval with each one of the other two, and the chord is consonant, or is a concord.[1]
Let us confine ourselves in the first place to intervals which are less than an Octave. The consonant intervals
within these limits, we have found to be :
1) the Fifth
\(C\) 0 |
\(G \tfrac32\) 702 |
\(F \tfrac43\) 498 |
\(A \tfrac53\) 884 |
\(E \tfrac54\) 386 |
\(E\flat \tfrac65\) 316 |
\(A\flat \tfrac85\) 814 |
\(G \tfrac32\) 702 |
||||||
\(F \tfrac43\) 498 |
Second \(\tfrac98\) 204 |
|||||
\(A \tfrac53\) 884 |
Second \(\tfrac{10}{9}\) 182 |
Third \(\tfrac54\) 386 |
||||
\(E \tfrac54\) 386 |
Third \(\tfrac65\) 316 |
Second \(\tfrac{16}{15}\) 112 |
\(\tfrac43\) 498 |
|||
\(E\flat \tfrac65\) 316 |
Third \(\tfrac54\) 386 |
Second \(\tfrac{10}{9}\) 182 |
Fourth \(\tfrac{25}{18}\) 568 |
Second \(\tfrac{25}{24}\) 70 |
||
\(A\flat \tfrac85\) 814 |
Second \(\tfrac{16}{15}\) 112 |
Third \(\tfrac65\) 316 |
Second \(\tfrac{25}{24}\) 70 |
Fourth \(\tfrac{32}{25}\) 428 |
\(\tfrac43\) 498 |
|
\(^7B\flat \tfrac74\) 969 |
Third \(\tfrac76\) 267 |
Fourth \(\tfrac{21}{16}\) 471 |
Second \(\tfrac{21}{20}\) 85 |
Fifth \(\tfrac75\) 583 |
Fifth \(\tfrac{35}{24}\) 653 |
Second \(\tfrac{35}{32}\) 155 |
From this it follows that the only consonant triads or chords of three notes, that can possibly exist within the compass of an Octave are the following: —
The two first of these triads are considered in musical theory as the fundamental triads from which all others are
deduced. They may each be regarded as composed of two Thirds, one major and the other minor, superimposed in different
orders. The chord
The next two chords,
The two last chords,
Collecting these inversions, the six consonant triads will assume the following form [the numbers shewing their correspondence with the forms on p. 212d]: —
We must observe that although the natural or subminor Seventh \(^7B\flat\) forms a
The triad
On the pianoforte it would seem as if this triad, which for practical purposes may be written either
The harmonious effect of the various inversions of triads already found depends in the first place upon the greater or less perfection of the consonance of the several intervals they contain. We have found that the Fourth is less agreeable than the Fifth, and that minor are less agreeable than major Thirds and Sixths. Now the triad
|
has a Fifth, a major Third, and a minor Third |
|
has a Fourth, a minor Third, and a minor Sixth |
|
has a Fourth, a major Third, and a major Sixth |
|
has a Fifth, a minor Third, and a major Third |
|
has a Fourth, a major Third, and a major Sixth |
|
has a Fourth, a minor Third, and a minor Sixth |
For just intervals the Thirds and Sixths decidedly disturb the general tunefulness more than the Fourths, and hence the major chords of the Sixth and Fourth are more harmonious than those in the fundamental position, and these again than the chords of the Sixth and Third. On the other hand the minor chords of the Sixth and Third are more agreeable than those in the fundamental position, and these again are better than the minor chords of the Sixth and Fourth. This conclusion will be found perfectly correct for the middle parts of the scale, provided the intervals are all justly intoned. The chords must be struck separately, and not connected by any modulation. As soon as modulational connections are allowed, as for example in a concluding cadence, the tonic feeling, which finds repose in the tonic chord, disturbs the power of observation, which is here the point of importance. In the lower parts of the scale either major or minor Thirds are more disagreeable than Sixths.
Judging merely from the intervals we should expect that the minor triad
Hence we must determine the combinational tones of the major and minor triads. We shall confine ourselves to the combinational tones of the first order produced by the primes and the first upper partial tones. In the following examples the primes are marked as minims, the combinational tones resulting from these primes are represented by crotchets, those from the primes and first upper partials by quavers and semiquavers. A downward sloping line, when placed before a note, shews that it represents a tone slightly deeper than that of the note in the scale which it precedes.
1.) Major Triads with their Combinational Tones:[6]
2.) Minor Triads with their Combinational Tones:[7]
In the major triads the combinational tones of the first order, and even the deeper combinational tones of the second order (written as crotchets and quavers) are merely doubles of the tones of the triad in deeper Octaves. The higher combinational tones of the second order (written as semiquavers) are extremely weak, because, other conditions being the same, the intensity of combinational tones decreases as the interval between the generating tones increases, with which again the high position of these combinational tones is connected. I have always been able to hear the deeper combinational tones of the second order, written as quavers, when the tones have been played on an harmonium, and the ear was assisted by the proper resonators: [8] but I have not been able to hear those written with semiquavers. They have been added merely to make the theory complete. Perhaps they might be occasionally heard from very loud musical tones having powerful upper partials. But they may be certainly neglected in all ordinary cases.
For the minor triads, on the other hand, the combinational tones of the first order, which are easily audible,
begin to disturb the harmonious effect. They are not near enough indeed to beat, but they do not belong to the
harmony. For the fundamental triad, and that of the Sixth and Third [the two first chords], these combinational tones,
written as crotchets, form the major triad
Every minor Third and every Sixth when associated with its principal com
binational tone, becomes at once a major chord.
Modern harmonists are unwilling to acknowledge that the minor triad is less consonant than the major. They have probably made all their experiments with tempered instruments, on which, indeed, this distinction may perhaps be allowed to be a little doubtful. But on justly intoned instruments [13] and with a moderately piercing quality of tone, the difference is very striking and cannot be denied. The old musicians, too, who composed exclusively for the voice, and were consequently not driven to enfeeble consonances by temperament, shew a most decided feeling for that difference. To this feeling I attribute the chief reason for their avoidance of a minor chord at the close. The medieval composers down to Sebastian Bach used for their closing chords either exclusively major chords, or doubtful chords without the Third; and even Handel and Mozart occasionally conclude a minor piece of music with a major chord. Of course other considerations, besides the degree of consonance, have great weight in determining the final chord, such as the desire to mark the prevailing tonic or key-note with distinctness, for which purpose the major chord is decidedly superior. More upon this in Chapter XV.
After having examined the consonant triads which lie within the compass of an Octave, we proceed to those with wider
intervals. We have found in general that consonant intervals remain consonant when one of their tones is transposed an
Octave or two higher or lower at pleasure, although such transposition has some effect on its degree of
harmoniousness. It follows, then, that in all the consonant chords which we have hitherto found, any one of the tones
may be transposed some Octaves higher or lower at pleasure. If the three intervals of the triad were consonant before,
they will remain so after transposition. We have already seen how the chords of the Sixth and Third, and of the Sixth
and Fourth, were thus obtained from the fundamental form. It follows further that when larger intervals are admitted,
no consonant triads can exist which are not generated by the transposition of the major and minor triads. Of course if
such other chords could exist, we should be able by transposition of their tones to bring them within the compass of
an Octave, and we should thus obtain a new consonant triad within this compass, whereas our method of discovering
consonant triads enabled us to determine every one that could lie within that compass. It is certainly true that
slightly dissonant chords which lie within the compass of an Octave are sometimes rendered smoother by transposing one
of their tones. Thus the chord
The transposition of some tones in a consonant triad, for the purpose of widening their intervals, affects their harmoniousness in the first place by changing the intervals. Major Tenths, as we found in Chapter X. p. 195b, sound better than major Thirds, but minor Tenths worse than minor Thirds, the major and minor Thirteenth worse than the minor Sixth (p. 196a). The following rule embraces all the cases: — Those intervals in which the smaller of the two numbers expressing the ratios of the pitch numbers is EVEN, are IMPROVED by having one of their tones transposed by an Octave, because the numbers expressing the ratio are thus diminished.
Those intervals in which the smaller of the two numbers expressing the ratio of the vibrational numbers is
ODD, are MADE WORSE by having one of their tones transposed by an Octave, as
the Fourth
Besides this the principal combinational tones are of essential importance. An example of the first combinational tones of the consonant intervals within the compass of an Octave is given below, the primary tones being represented by minims and the combinational tones by crotchets, as before.[18]
The upwards sloping line prefixed to \(f''\) denotes a degree of sharpening of about a quarter of a Tone [53 cents]; and the downwards sloping line prefixed to \(b'\flat\) flattens it [by 27 cents] to the subminor Seventh of \(c\). Below the notes are added the names of the intervals, the numbers of the ratios, and the differences of those numbers, giving the pitch numbers of the several combinational tones.
We find in the first place that the combinational tones of the Octave, Fifth, Twelfth, Fourth, and major Third are merely transpositions of one of the primary tones by one or more Octaves, and therefore introduce no foreign tone. Hence these five intervals can be used in all kinds of consonant triads, without disturbing the effect by the combinational tones which they introduce. In this respect the major Third is really superior to the major Sixth and the Tenth in the construction of chords, although its independent harmoniousness is inferior to that of either.
The double Octave introduces the Fifth as a combinational tone. Hence if the fundamental tone of a chord is doubled by means of the double Octave, the chord is not injured. But injury would ensue if the Third or Fifth of the chord were doubled in the double Octave.
Then we have a series of intervals which are made into complete major triads by means of their combinational tones, and hence produce no disturbance in major chords, but are injurious to minor chords. These are the Eleventh, minor Third, major Tenth, major Sixth, and minor Sixth.
But the minor Tenth, and the major and minor Thirteenth cannot form part of a chord without injuring its consonance by their combinational tones.
We proceed to apply these considerations to the construction of triads.
Major triads can be so arranged that the combinational tones remain parts of the chord. This gives the most perfectly harmonious positions of these chords. To find them, remember that no minor Tenths and no [major or minor] Thirteenths are admissible, so that the minor Thirds and [both major and minor] Sixths must be in their closest position. By taking as the uppermost tone first the Third, then 51 the Fifth, and lastly the fundamental tone, we find the following positions of these chords, within a compass of two Octaves, in which the combinational tones (here written as crotchets as usual) do not disturb the harmony.
When the Third lies uppermost, the Fifth must not be more than a major Sixth below, as otherwise a [major] Thirteenth would be generated. But the fundamental tone can be transposed. Hence when the Third is uppermost the only two positions which are undisturbed are Nos. 1 and 2. When the Fifth lies uppermost, the Third must be immediately under it, or otherwise a minor Tenth would be produced; but the fundamental tone may be transposed. Finally, when the fundamental tone is uppermost, the major Third can lie only in the position of a minor Sixth below it, but the Fifth may be placed at pleasure. Hence it follows that the only possible positions of the major chord which will be entirely free from disturbance by combinational tones, are the six here presented, among which we find the three close positions Nos. 2, 4, 6 already mentioned [p. 215a], and three new ones Nos. 1, 3, 5. Of these new positions two (Nos. 1, 3) have the fundamental tone in the bass, just as in the primary form, and are considered as open positions of that form, while the third (No. 5) has the Fifth in the bass, just as in the chord of the Sixth and Fourth [of which it is also considered as an open position]. The chord of the Sixth [and Third] (No. 6), on the other hand, admits of no opener position [if it is to remain perfectly free from combinational disturbance].
The order of these chords in respect to harmoniousness of the intervals is, perhaps, the same as that presented above. The three intervals of No. 1 (the Fifth, major Tenth, and major Sixth) are the best, and those of No. 6 (the Fourth, minor Third, and minor Sixth) are relatively the most unfavourable of the intervals that occur in these chords.
The remaining positions of the major triads present individual unsuitable combinational tones, and on justly intoned instruments are unmistakably rougher than those previously considered, but this does not make them dissonant, it merely puts them in the same category as minor chords. We obtain all of them which lie within the compass of two Octaves, by making the transpositions forbidden in the last cases. They are as follows, in the same order as before, No. 7 being made from No. 1, and so on: —
Musicians will immediately perceive that these positions of the major triad are much less in use. The combinational
tone \(^7b'\flat\) gives the positions 7 to 10 something of the character of the chord of the dominant
Seventh in the key of \(F\) major,
No minor chord can be obtained perfectly free from false combinational tones, because its Third can never be so placed relatively to the fundamental tone, as not to produce a combinational tone unsuitable to the minor chord. If only one such tone is admitted, the Third and Fifth of the minor chord must lie close together and form a major Third, because in any other position they would produce a second unsuitable combinational tone. The fundamental tone and the Fifth must never be so placed as to form an Eleventh, because in that case the resulting combinational tone would make them into a major triad. These conditions can be fulfilled by only three positions of the minor chord, as follows: —
The remaining positions which do not sound so well are: —
The positions Nos. 4 to 10 each produce two unsuitable combinational tones, one of which necessarily results from the
fundamental tone and its [minor] Third; the other results in No. 4 from the Eleventh
The influence of the combinational tones may be recognised by comparing the different positions. Thus the position
No. 3, with a minor Tenth
This influence of bad combinational tones is also apparent from a comparison with the major chords. On comparing the minor chords Nos. 1 to 3, each of which has only one bad combinational tone, with the major chords Nos. 11 and 12, each of which has two such tones, those minor chords will be found really pleasanter and smoother than the major. Hence in these two classes of chords it is not the major and minor Third, nor the musical mode, which decides the degree of harmoniousness, it is wholly and solely the combinational tones.
It is easily seen that all consonant tetrads must be either major or minor triads to which the Octave of one of the
tones has been added.[23] For every consonant tetrad must admit
of being changed into a consonant triad by removing one of its tones. Now this can be done in four ways, so that, for
example, the tetrad
Any such triad, if it is not merely a dyad, or interval of two tones, with the Octave of one added, must be either a major or a minor triad, because there are no other consonant triads. But the only way of adding a fourth tone to a major or minor triad, on condition that the result should be consonant, is to add the Octave of one of its tones. For every such triad contains two tones, say \(C\) and \(G\), which form either a direct or inverted Fifth. Now the only tones which can be combined with \(C\) and \(G\) so as to form a consonance are \(E\) and \(E\flat \); there are no others at all. But \(E\) and \(E\flat \) cannot be both present in the same consonant chord, and hence every consonant chord of four or more parts, which contains \(C\) and \(G\), must either contain \(E\) and some of the Octaves of \(C, \; E, \; G,\) or else \(E\flat \) and some of the Octaves of \(C, \; E\flat , \; G\).
Every consonant chord of three or more parts will therefore be either a major or a minor chord, and may be formed from the fundamental position of the major and minor triad, by transposing or adding the Octaves above or below some or all of its three tones.
To obtain the perfectly harmonious positions of major tetrads, we have again to be careful that no minor Tenths and no [major or minor] Thirteenths occur. Hence the Fifth may not stand more than a minor Third above, or a Sixth below the Third of the chord; and the fundamental tone must not be more than a Sixth above the Third. When these rules are carried out, the avoidance of the minor Thirteenths is effected by not taking the double Octave of the Third and Fifth. These rules may be briefly enunciated as follows: Those major chords are most harmonious in which the fundamental tone or the Fifth does not lie more than a Sixth above the Third, or the Fifth does not lie more than a Sixth above or below it. The fundamental tone, on the other hand, may be as far below the Third as we please.
The corresponding positions of the major tetrads are found by combining any two of the more perfect positions of the major triads which have two tones in common, as follows, where the lower figures refer to the positions of the major triads already given.
We see that chords of the Sixth and Third must he quite close, as No. 7 ; [25] and that chords of the Sixth and Fourth [26] must not have a compass of more than an Eleventh, but may occur in all the three positions (Nos. 5, 6, 11) in which it can be constructed within this compass. Chords which have the fundamental tone in the bass can be handled most freely.
It will not be necessary to enumerate the less perfect positions of major tetrads. They cannot have more than two unsuitable combinational tones, as in the 12th position of the major triads, p. 220c. The major triads of \(C\) can only have the false combinational tones marked \(^7b\flat \) and \(^{11}f\), [that is, with pitch numbers bearing to that of \(C\) the ratios 7 : 1, or 11 : 1].
Minor tetrads, like the corresponding triads, must at least have one false combinational tone. There is only one single position of the minor tetrad which has only one such tone. It is No. 1 in the following example, and is compounded of the positions Nos. 1 and 2 of the minor triads on p. 221b. But there may be as many as 4 false combinational tones, as, for example, on combining positions Nos. 10 and 11 of the minor triads, p. 221c.
Here follows a list of the minor tetrads which have not more than two false combinational tones, and which lie within the compass of two Octaves. The false combinational tones only are noted in crotchets, and those which suit the chord are omitted.
The chord of the Sixth and Fourth [marked \(6 \atop 4\)] occurs only in its closest position, No. 5 ; but that of the Sixth and Third [marked \(6 \atop 3\)] is found in three positions (Nos. 3, 6, and 9), namely, in all positions where the compass of the chord does not exceed a Tenth ; the fundamental chord occurs three times with the Octave of the fundamental note added (Nos. 1, 2, 4), and twice with the Octave of the Fifth added (Nos. 7, 8).
In musical theory, as hitherto expounded, very little has been said of the influence of the transposition of chords on harmonious effect. It is usual to give as a rule that close intervals must not be used in the bass, and that the intervals should be tolerably evenly distributed between the extreme tones. And even these rules do not appear as consequences of the theoretical views and laws usually given, according to which a consonant interval remains consonant in whatever part of the scale it is taken, and however it may be inverted or combined with others. They rather appear as practical exceptions from general rules. It was left to the musician himself to obtain some insight into the various effects of the various positions of chords by mere use and experience. No rule could be given to guide him.
The subject has been treated here at such length in order to shew that a right view of the cause of consonance and dissonance leads to rules for relations which previous theories of harmony could not contain. The propositions we have enunciated agree, however, with the practice of the best composers, of those, I mean, who studied vocal music principally, before the great development of instrumental music necessitated the general introduction of tempered intonation, as any one may easily convince himself by examining those compositions which aimed at producing an impression of perfect harmoniousness. Mozart is certainly the composer who had the surest instinct for the delicacies of his art. Among his vocal compositions the Ave verum corpus is particularly celebrated for its wonderfully pure and smooth harmonies. On examining this little piece as one of the most suitable examples for our purpose, we find in its first clause, which has an extremely soft and sweet effect, none but major chords, and chords of the dominant Seventh. All these major chords belong to those which we have noted as being the more perfectly harmonious. Position 2 occurs most frequently, and then 8, 10, 1, and 9 [of p. 223c]. It is not till we come to the final modulation of this first clause that we meet with two minor chords, and a major chord in an unfavourable position. It is very striking, by way of comparison, to find that the second clause of the same piece, which is more veiled, longing, and mystical, and laboriously modulates through bolder transitions and harsher dissonances, has many more minor chords, which, as well as the major chords scattered among them, are for the most part brought into unfavourable positions, until the final chord again restores perfect harmony.
Precisely similar observations may be made on those choral pieces of Palestrina, and of his contemporaries and successors, which have a simple harmonic construction without any involved polyphony. In transforming the Roman Church music, which was Palestrina’s task, the principal weight was laid on harmonious effect in contrast to the harsh and unintelligible polyphony of the older Netherland[28] system, and Palestrina and his school have really solved the problem in the most perfect manner. Here also we find an almost uninterrupted flow of consonant chords, with some dominant Sevenths, or dissonant passing notes, charily interspersed. Here also the consonant chords wholly, or almost wholly, consist of those major and minor chords which we have noted as being in the more perfect positions. Only in the final cadence of a few clauses, on the contrary, in the midst of more powerful and more frequent dissonances, we find a predominance of the unfavourable positions of the major and minor chords. Thus that expression which modern music endeavours to attain by various discords and an abundant introduction of dominant Sevenths, was obtained in the school of Palestrina by the much more delicate shading of various inversions and positions of consonant chords. This explains the harmoniousness of these compositions, which are nevertheless full of deep and tender expression, and sound like the songs of angels with hearts affected but undarkened by human grief in their heavenly joy. Of course such pieces of music require fine ears both in singer and hearer, to let the delicate gradation of expression receive its due, now that modern music has accustomed us to modes of expression so much more violent and drastic.
The great majority of major tetrads in Palestrina’s Stabat mater are in the positions 1, 10, 8, 5, 3, 2, 4, 9 [of p. 223c], and of minor tetrads in the positions 9, 2, 4, 3, 5, 1 [of p. 224a]. For the major chords one might almost think that some theoretical rule led him to avoid the bad intervals of the minor Tenth and the [major or minor] Thirteenth. But this rule would have been entirely useless for minor chords. Since the existence of combinational tones was not then known, we can only conclude that his fine ear led him to this practice, and that the judgment of that ear exactly agreed with the rules deduced from our theory.
These authorities may serve to lead musicians to allow the correctness of my arrangement of consonant chords in the order of their harmoniousness. But any one can convince himself of their correctness on any justly intoned instrument [as the Harmonical]. The present system of tempered intonation certainly obliterates somewhat of the more delicate distinctions, without, however, entirely destroying them.
Having thus concluded that part of our investigations which rests upon purely scientific principles, it will be advisable to look back upon the road we have travelled in order to review our gains, and examine the relation of our results to the views of older theoreticians. We started from the acoustical phenomena of upper partial tones, combinational tones and beats. These phenomena were long well known both to musicians and acousticians, and the laws of their occurrence were, at least in then-essential features, correctly recognised and enunciated. We had only to pursue these phenomena into further detail than had hitherto been done. We succeeded in finding methods for observing upper partial tones, which rendered comparatively easy an observation previously very difficult to make. And with the help of this method we endeavoured to shew that, with few exceptions, the tones of all musical instruments were compounded of partial tones, and that, in especial, those qualities of tone which are more particularly favourable for musical purposes, possess at least a series of the lower partial tones in tolerable force, while the simple tones, like those of stopped organ pipes, have a very unsatisfactory musical effect, although even these tones when loudly sounded are accompanied in the ear itself by some weak harmonic upper partials. On the other hand we found that, for the better musical qualities of tone, the higher partial tones, from the Seventh onwards, must be weak, as otherwise the quality, and every combination of tones would be too piercing. In reference to the beats, we had to discover what became of them when they grew quicker and quicker. We found that they then fell into that roughness which is the peculiar character of dissonance. The transition can be effected very gradually, and observed in all its stages, and hence it is apparent to the simplest natural observation that the essence of dissonance consists merely [29] in very rapid beats. The nerves of hearing feel these rapid beats as rough and unpleasant, because every intermittent excitement of any nervous apparatus affects us more powerfully than one that lasts unaltered. With this there is possibly associated a psychological cause. The individual pulses of tone in a dissonant combination give us certainly the same impression of separate pulses as slow beats, although we are unable to recognise them separately and count them; hence they form a tangled mass of tone, which cannot be analysed into its constituents. The cause of the unpleasantness of dissonance we attribute to this roughness and entanglement. The meaning of this distinction may be thus briefly stated: Consonance is a continuous, dissonance an intermittent sensation of tone. Two consonant tones flow on quietly side by side in an undisturbed stream; dissonant tones cut one another up into separate pulses of tone. This description of the distinction at which we have arrived agrees precisely with Euclid’s old definition, 'Consonance is the blending of a higher with a lower tone. Dissonance is incapacity to mix, when two tones cannot blend, but appear rough to the ear.'
After this principle had been once established there was nothing further to do but to inquire under what circumstances, and with what degree of strength, beats would arise in the various combinations of tones through either the partial or the combinational tones. This investigation had hitherto been completely worked out by Scheibler for the combinational tones of two simple tones only. The law of beats being known, it became easy to extend it to compound tones. Every theoretical conclusion on this field can be immediately checked by a proper observation, when the analysis of a mass of tone is facilitated by the use of resonators. All these beats of partial and combinational tones, of which so much has been said in the last chapter, are not inventions of empty theoretical speculation, but rather facts of observation, and can be really heard without difficulty by any practised observer who performs his experiments correctly. The knowledge of the acoustic law facilitates our discovery of the phenomena in question. But all the assertions on which we depend for establishing a theory of consonance and dissonance, such as was given in the last chapters, are founded wholly and solely on a careful analysis of the sensations of hearing, an analysis which a practised ear could have executed without any theoretical assistance, although of course the task was immensely facilitated by the guidance of theory and the assistance of appropriate instruments of observation.
For these reasons the reader is particularly requested to observe that my hypothesis concerning the sympathetic vibration of Corti’s organs inside the ear has no immediate connection whatever with the explanation of consonance and dissonance. That explanation depends solely upon observed facts, on the beats of partial tones and the beats of combinational tones. Yet I thought it right not to suppress my hypothesis (which must of course be regarded solely as an hypothesis), because it gathers all the various acoustical phenomena with which we are concerned into one sheaf, and gives a clear, intelligible, and evident explanation of the whole phenomena and their connection.
The last chapters have shewn, that a correct and careful analysis of a mass of sound under the guidance of the principles cited, leads to precisely the same distinctions between consonant and dissonant intervals and chords, as have been established under the old theory of harmony. We have even shewn that these investigations give more particular information concerning individual intervals and chords than was possible with the general rules of the former theory, and that the correctness of these rules is corroborated both by observation on justly intoned instruments and the practice of the best composers.
Hence I do not hesitate to assert that the preceding investigations, founded upon a more exact analysis of the sensations of tone, and upon purely scientific, as distinct from esthetic principles, exhibit the true and sufficient cause of consonance and dissonance in music. One circumstance may, perhaps, cause the musician to pause in accepting this assertion. We have found that from the most perfect consonance to the most decided dissonance there is a continuous series of degrees, of combinations of sound, which continually increase in roughness, so that there cannot be any sharpy line drawn between consonance and dissonance, and the distinction would therefore seem to be merely arbitrary. Musicians, on the contrary, have been in the habit of drawing a sharp line between consonances and dissonances, allowing of no intermediate links, and Hauptmann advances this as a principal reason against any attempt at deducing the theory of consonance from the relations of rational numbers.[30]
As a matter of fact we have already remarked that the chords of the natural or subminor Seventh 4 : 7
[
The decision does not depend, then, on the nature of the intervals themselves but on the construction of the whole
tonal system. This is corroborated by the fact that the boundary between consonant and dissonant intervals has not
been always the same. It has been already mentioned that the Greeks always represented Thirds as dissonant, and
although the original Pythagorean Third
But if the boundary between consonance and dissonance has really changed with a change of tonal system, it is manifest that the reason for assigning this boundary does not depend on the intervals and their individual musical effect, but on the whole construction of the tonal system.
The enigma which, about 2500 years ago, Pythagoras proposed to science, which investigates the reasons of things, 'Why is consonance determined by the ratios of small whole numbers?' has been solved by the discovery that the ear resolves all complex sounds into pendular oscillations, according to the laws of sympathetic vibration, and that it regards as harmonious only such excitements of the nerves as continue without disturbance. The resolution into partial tones, mathematically expressed, is effected by Fourier’s law, which shews how any periodically variable magnitude, whatever be its nature, can be expressed by a sum of the simplest periodic magnitudes.[32] The length of the periods of the simply periodic terms of this sum must be exactly such, that either one or two or three or four, and so on, of their periods are equal to the period of the given magnitude. This, reduced to tones, means that the pitch numbers of the partial tones must be exactly once, twice, three times, four times, and so on, respectively, as great as that of the prime tone. These are the whole numbers which determine the ratios of the consonances. For, as we have seen, the condition of consonance is that two of the lower partial tones of the notes combined shall be of exactly the same pitch; when they are not, disturbance arises from beats. Ultimately, then, the reason of the rational numerical relations of Pythagoras is to be found in the theorem of Fourier, and in one sense this theorem may be considered as the prime source of the theory of harmony.[33]
The relation of whole numbers to consonance became in ancient times, in the middle ages, and especially among Oriental nations, the foundation of extravagant and fanciful speculation. ‘ Everything is Number and Harmony,’ was the characteristic principle of the Pythagorean doctrine. The same numerical ratios 1T which exist between the seven tones of the diatonic scale, were thought to be found again in the distances of the celestial bodies from the central fire. Hence the harmony of the spheres, which was heard by Pythagoras alone among mortal men, as his disciples asserted. The numerical speculations of the Chinese in primitive times reach as far. In the book of Tso-kiu-ming, a friend of Confucius (b.c. 500), the five tones of the old Chinese scale were compared with the five elements of their natural philosophy — water, fire, wood, metal, and earth. The whole numbers 1, 2, 3 and 4 were described as the source of all perfection. At a later time the 12 Semitones of the Octave were connected with the 12 months in the year, and so on. Similar references of musical tones to the elements, the temperaments, and the constellations are found abundantly scattered among the musical writings of the Arabs. The harmony of the spheres plays a great part throughout the middle ages. According to Athanasius Kircher, not only the macrocosm, but the microcosm is musical. Even Keppler, a man of the deepest scientific spirit, could not keep himself free from imaginations of this kind. Nay, even in the most recent times, theorising friends of music may be found who will rather feast on arithmetical mysticism than endeavour to hear upper partial tones.
The celebrated mathematician Leonard Euler[34] tried, in a more serious and more scientific manner, to found the relations of consonances to whole numbers upon psychological considerations, and his theory may certainly be regarded as the one which found most favour with scientific investigators during the last century, although it perhaps did not entirely satisfy them. Euler [35] begins by explaining that we are pleased with everything in which we can detect a certain amount of perfection. Now the perfection of anything is determined by the co-operation of all its parts towards the attainment of its end. Hence it follows that wherever perfection is to be found there must be order; for order consists in the arrangement of all parts by a certain law from which we can discover why each part lies where it is, rather than in any other place. Now in any perfect object such a law of arrangement is determined by the end to be attained which governs all the parts. For this reason order pleases us more than disorder. Now order can be perceived in two ways: either we know the law whence the arrangement is deduced, and compare the deductions from this law with the arrangements observed; or, we observe these arrangements and endeavour to determine the law from them. The latter is the case in music. A combination of tones will please us when we can discover the law of their arrangement. Hence it may well happen that one hearer finds it and that another does not, and that their judgments consequently differ.
The more easily we perceive the order which characterises the objects contemplated, the more simple and more perfect will they appear, and the more easily and joyfully shall we acknowledge them. But an order which costs trouble to discover, though it will indeed also please us, will associate with that pleasure a certain degree of weariness and sadness (tristitia).
Now in tones there are two things in which order is displayed, pitch and duration. Pitch is ordered by intervals, duration by rhythm. Force of tone might also be ordered, had we a measure for it. Now in rhythm two or three or four equally long notes of one part may correspond with one or two or three of another, in which the regularity of the arrangement is easily observed, especially when frequently repeated, and gives considerable pleasure. Similarly in intervals we should derive more pleasure from observing that two, three, or four vibrations of one tone coincided with one, two, or three of another, than we could possibly experience if the ratios of the time of vibration were incommensurable with one another, or at least could not be expressed except by very high numbers. Hence it follows that the combination of two tones pleases us the more, the smaller the two numbers by which the ratios of their periods of vibration can be expressed. Euler also remarked that we could better endure more complicated ratios of the periods of vibration, and consequently less perfect consonances, for higher than for deeper tones, because for the former the groups of vibrations which were arranged to occur in equal times, were repeated more frequently than in the latter, and we were consequently better able to recognise the regularity of even a more involved arrangement.
Hereupon Euler develops an arithmetical rule for calculating the degree of harmoniousness of an interval or a chord from the ratios of the periods of the vibrations which characterise the intervals. The Unison belongs to the first degree, the Octave to the second, the Twelfth and Double Octave to the third, the Fifth to the fourth, the Fourth to the fifth, the major Tenth and Eleventh to the sixth, the major Sixth and major Third to the seventh, the minor Sixth and minor Third to the eighth, the subminor Seventh 4 : 7 to the ninth, and so on. To the ninth degree belongs also the major triad, both in its closest position and in the position of the Sixth and Fourth. The major chord of the Sixth and Third belongs, however, to the tenth degree. The minor triad, both in its closest and in its position of the Sixth and Third, also belongs to the ninth degree, but its position of the Sixth and Fourth to the tenth degree. In this arrangement the consequences of Euler’s system agree tolerably well with our own results, except that in determining the relation of the major to the minor triad, the influence of combinational tones was not taken into account, but only the kinds of interval. Hence both triads in their close position appear to be equally harmonious, although again both the major chord of the Sixth and Third, and the minor chord of the Sixth and Fourth, are inferior with him as with us.[36]
Euler has not confined these speculations to single consonances and chords, but has extended them to their results, to the construction of scales, and to modulations, and brought out many surprising specialities correctly. But without taking into account that Euler’s system gives no explanation of the reason why a consonance when slightly out of tune sounds almost as well as one justly tuned, and much better than one greatly out of tune, although the numerical ratio for the former is generally much more complicated, it is very evident that the principal difficulty in Euler’s theory is that it says nothing at all of the mode in which the mind contrives to perceive the numerical ratios of two combined tones. We must not forget that a man left to himself is scarcely aware that a tone depends upon vibrations. Moreover, immediate and conscious perception by the senses has no means of discovering that the numbers of vibrations performed in the same time are different, greater for high than for low tones, and that determinate intervals have determinate ratios of these numbers. There are certainly many perceptions of the senses in which a person is not precisely able to account for the way in which he has attained to his knowledge, as when from the resonance of a space he judges of its size and form, or when he reads the character of a man in his features. But in such cases a person has generally had a large experience in such relations, which helps him to form a judgment in analogous circumstances, without having the previous circumstances on which his judgment depends clearly present to his mind. But it is quite different with pitch numbers. A man that has never made physical experiments has never in the whole course of his life had the slightest opportunity of knowing anything about pitch numbers or their ratios. And almost every one who delights in music remains in this state of ignorance from birth to death.
Hence it would certainly be necessary to shew how the ratios of pitch numbers can be perceived by the senses. It has been my endeavour to do this, and hence the results of my investigation may be said, in one sense, to fill up the gap which Euler’s left. But the physiological processes which make the difference sensible between consonance and dissonance, or, in Euler’s language, orderly and disorderly relations of tone, ultimately bring to light an essential difference between our method of explanation and Euler’s. According to the latter, the human mind perceives commensurable ratios of pitch numbers as such; according to our method, it perceives only the physical effect of these ratios, namely, the continuous or intermittent sensation of the auditory nerves.[37] The physicist knows, indeed, that the reason why the sensation of a consonance is continuous is that the ratios of its pitch numbers are commensurable, but when a man who is unacquainted with physics, hears a piece of music, nothing of the sort occurs to him,[38] nor does the physicist find a chord in any respect more harmonious because he is better acquainted with, the cause of its harmoniousness.[39] It is quite different with the order of rhythm. That exactly two crotchets, or three in a triplet, or four quavers go to one minim is perceived by any attentive listener without the least instruction. But while the orderly relation (or commensurable ratio) of the vibrations of two combined tones, on the other hand, undoubtedly affects the ear in a certain way which distinguishes it from any disorderly relation (incommensurable ratio), this difference of consonance and dissonance depends on physical, not psychological grounds.
The considerations advanced by Rameau[40] and d’Alembert[41] on the one side, and Tartini[42] on the other, concerning the cause of consonance agree better with our theory. The last founded his theory on the existence of combinational tones, the two first on that of upper partial tones. As we see, they had found the proper points of attack, but the acoustical knowledge of last century did not allow of their drawing sufficient consequences from them. According to d’Alembert, Tartini’s book was so darkly and obscurely written that he, as well as other well-instructed people, were unable to form a judgment upon it. D’Alembert’s book, on the other hand, is an extremely clear and masterly performance, such as was to be expected from a sharp and exact thinker, who was at the same time one of the greatest physicists and mathematicians of his time. Rameau and d’Alembert lay down two facts as the foundation of their system. The first is that every resonant body audibly produces at the same time as the prime (générateur) its Twelfth and next higher Third, as upper partials (harmoniques). The second is that the resemblance between any tone and its Octave is generally apparent. The first fact is used to shew that the major chord is the most natural of all chords, and the second to establish the possibility of lowering the Fifth and the Third by one or two Octaves without altering the nature of the chord, and hence to obtain the major triad in all its different inversions and positions. The minor triad is then found by the condition that all three tones should have the same upper partial or harmonic, namely, the Fifth of the chord (in fact \(C, \; E\flat \) and \(G\) have all the same upper partial \(g'\)). Hence although the minor chord is not so perfect and natural as the major, it is nevertheless prescribed by nature.
In the middle of the eighteenth century, when much suffering arose from an artificial social condition, it may have been enough to shew that a thing was natural, in order at the same time to prove that it must also be beautiful and desirable. Of course no one who considers the great perfection and suitability of all organic arrangements in the human body, would, even at the present day, deny that when the existence of such natural relations have been proved as Rameau discovered between the tones of the major triad, they ought to be most carefully considered, at least as starting-points for further research. And Rameau had indeed quite correctly conjectured, as we can now perceive, that this fact was the proper basis of a theory of harmony. But that is by no means everything. For in nature we find not only beauty but ugliness, not only help but hurt. Hence the mere proof that anything is natural does not suffice to justify it esthetically. Moreover if Rameau had listened to the effects of striking rods, bells, and membranes, or blowing over hollow chambers, he might have heard many a perfectly dissonant chord. And yet such chords cannot but be considered equally natural. That all musical instruments exhibit harmonic upper partials depends upon the selection of qualities of tone which man has made to satisfy the requirements of his ear.
Again the resemblance of the Octave to its fundamental tone, which was one of Rameau’s initial facts, is a musical phenomenon quite as much in need of explanation as consonance itself.
No one knew better than d’Alembert himself the gaps in this system. Hence in the preface to his book he especially guards himself against the expression: 'Demonstration of the Principle of Harmony,' which Rameau had used. He declares that so far as he himself is concerned, he meant only to give a well-connected and consistent account of all the laws of the theory of harmony, by deriving them from a single fundamental fact, the existence of upper partial tones or harmonics, which he assumes as given, without further inquiry respecting its source. He consequently limits himself to proving the naturalness of the major and minor triads. In his book there is no mention of beats, and hence of the real source of distinction between consonance and dissonance. Of the laws of beats very little indeed was known at that time, and combinational tones had only been just brought under the notice of French savants, by Tartini (1751) and Romieu (1753). They had been discovered a few years previously in Germany by Sorge (1745), but the fact was probably little known. Hence the materials were wanting for building up a more perfect theory.
Nevertheless this attempt of Rameau and d’Alembert is historically of great importance, in so far as the theory of consonance was thus for the first time shifted from metaphysical to physical ground. It is astonishing what these two thinkers effected with the scanty materials at their command, and what a clear, precise, comprehensive system the old vague and lumbering theory of music became under their hands. The important progress which Rameau made in the specially musical portion of the theory of harmony will be seen hereafter.
If, then, I have been myself able to present something more complete, I owe it merely to the circumstance that I had at command a large mass of preliminary physical results, which had accumulated in the century that has since elapsed.
1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 |
\(C\) | \(c\) | \(g\) | \({c'}\) | \({e'}\) | \({g'}\) | \({^7b'\flat} \) | \({c''}\) | \({d''}\) | \({e''}\) | \({^{11}f''}\) | \({g''}\) | \({^{13}a''}\) | \({^7b''\flat}\) | \({b''}\) | \({c'''}\) |
1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 |
\(A_{\prime\prime}\flat\) | \(A_{\prime}\flat\) | \(E\flat\) | \(A\flat\) | \(c\) | \(e\flat\) | \(^7g\flat\) | \(a\flat\) | \(b\flat\) | \(c'\) | \(^{11}d'\flat\) | \(e'\flat\) | \(^{13}f'\) | \(^7g'\flat\) | \(g'\) |
16 | 18 | 20 | 21 | 22 | 24 | 25 | 26 | 27 | 28 | 30 | 32 | 33 | 39 | 40 |
\(a'\flat\) | \(b'\flat\) | \(c''\) | \(^7d''\flat\) | \(^{11}d''\flat\) | \(e''\flat\) | \(e''\) | \(^{13}f''\) | \(f''\) | \(^7g''\flat\) | \(g''\) | \(a''\flat\) | \(^{11}a''\flat\) | \(^{13}c'''\) | \(c''\) |