A Dictionary of Music and Musicians/Tone

by Alfred James Hipkins

TONE, in the sense of Quality, the French timbre, is distinguished as harsh, mild, thin, full, hollow, round, nasal, metallic or woody; and most persons agree in assigning these epithets to varieties of tone as usually heard. No valid reason was forthcoming for the cause of these varieties until Helmholtz, in 'Die Lehre der Tonempfindungen,' settled its physical basis, demonstrating and explaining it by his theory of tone sensations. Since the publication of that great work the why and wherefore of differences of quality may be learned by all enquirers, without any preliminary knowledge of mathematics; and as there are admirable translations of Helmholtz's great work, in French by M. Gudroult, and in English by Mr. A. J. Ellis, those who wish to pursue the study of the subject will find no insurmountable hindrance to doing so.

If, as Helmholtz points out, the same note is sounded successively on a pianoforte, a violin, clarinet, oboe or trumpet, or by the human voice, though the pitch be the same and the force equal, the musical tone of each is different and may be at once recognised without seeing the instrument or singer. These varieties of quality are infinitely numerous, and we can easily distinguish one voice from another in singing or speaking even by memory, at distances of time and space; and by the delicate shades of quality in vowel tone we perceive that each individual is furnished with a distinct vocal instrument. This infinite gradation of tone is due to the fact that simple tones are very rarely heard, but that in nearly every musical sound, though accepted by the ear as one note, several notes are really heard in combination, and it is the different relative numbers and intensities of the notes combined that cause the sensation of different quality. In the analysis of the combination the lowest tone is called the 'Prime' or 'Fundamental,' and the higher ones, the 'Upper Partials.'^[1] The running off into upper partial tones is to be attributed, as Mr. Hermann Smith discovered, to the energy with which the sounding medium, whatever it may be, is agitated. The Æolian Harp is a beautiful instance of the influence of varying energy. In it several strings are tuned to one pitch, but they are not equally submitted to the force of the wind, and in consequence we hear lower or higher notes in combinations of concord or dissonance, as the strings vibrate in longer or shorter sections due to the less or greater power of the wind, and its point of impact on the string.^[2] The pulsations known as Beats, which may be heard by touching and holding down almost any key of a pianoforte not recently tuned, affect the ear by their frequency. If unapparent or nearly so, Helmholtz characterises the sound as 'continuous,' if perceptibly apparent as 'discontinuous,' and while continuity is harmonious and gratifies the ear, discontinuity is discordant and more or less pains the ear according to the frequency of the disconnection. Now the prime and upper partials which in strings, narrow tubes, reeds and the human voice form a musical note, proceed in a regular succession, the Arithmetical Progression of 1, 2, 3, 4, 5, 6, etc. This succession may also be expressed in ratios which show by fractions the vibrating divisions of the string. We express the same succession by Unison, Octave, Twelfth, Double Octave, etc. Up to 8, which is the Third Octave from the Prime or Fundamental, the successive combination of these increasing divisions of the string (or of the air column) is sufficiently continuous or free from prominent beats to satisfy the ear as harmonious, but that point passed, the greater frequency of beats caused by the increasing nearness of the successive partials causes a disagreeable sensation which is extreme when a string vibrating in 12 sections and another vibrating in 13, are sounding together. The reader must take for granted that for simple tones the particles vibrate like the bob of a pendulum. For compound tones the form of the vibration is very different. The particular form in any case depends upon the number and intensity of the partials or simple tones of which it is compounded, and produces the effect called quality of tone. There is another circumstance called 'phase,' depending upon the points of their vibrations in which two partials coincide, when compounded; this alters the form of vibration in the compound tone, but has no perceptible effect on its quality.

We have so far touched upon the voice, and those instruments of strings, reeds, and narrow pipes which may have a regular series of harmonic proper tones; there are however irregular causes of musical or partially musical sound with inharmonic proper tones, not following an arithmetical order of succession: among these are wide pipes, stretched membranes (as drums), plates (as gongs), elastic rods (as tuning-forks), and the various metal and wooden harmonicas. The use of nearly all these varieties is in consequence much restricted in our modern European music. As to Resonance, any elastic body fastened so as to be permitted to vibrate will have its own proper tones, and will respond sympathetically to the influence of other periodic vibrations, as may be commonly observed with violins, pianofortes, harps, and other stringed instruments, where the comparatively faint sound of the strings is materially reinforced by the responsive sound-board.

In many wind instruments the phenomena of Harmonics become of the first importance. In these they are caused by increase of pressure or force of blowing; and, in point of fact, as each higher note is gained by the rejection of a lower factor of sound, the quality of each note changes and gains in brilliancy as it ascends in pitch. In stringed instruments it is sufficient to touch the vibrating string gently with the finger, to damp all those simple vibrations which have segmental curves or loops at the point touched; while at the apparent resting-places from vibration which are called nodes, the simple vibrations meeting there continue to sound with undiminished loudness. The quality is changed from the full sounding note; the vibrating complex being simpler, sounds sweeter and purer, until in the very highest harmonics the difference to the ear between string and wind seems almost lost. The greater consistency of metal assists the maintenance of a state of vibrating motion once assumed, and from this what we characterise as metallic tone is the comparatively steady lasting of the high upper partial tones, but with the possible fault of becoming tinkling. In the less elastic mass of wood, the upper partials rapidly die away. Unless this decrease be too rapid the ear delights in the greater prominence gained for the prime and its nearer upper partials. If too rapid we characterise the tone as woody.

In the Pianoforte we meet with the readiest application of the terms 'metallic' and 'woody.' Modern pianos, where the framing which holds the strings and bears their draught is of iron, frequently have a 'metallic' tone from the higher elasticity of the framing, which being metal does not allow the high upper partials of the string to die away so soon as they did in the older pianos of iron and wood or of wood alone, the inferior elasticity of which permitted them to become extinct sooner and the string to pass more quickly into longer segments of vibration. The extreme influence of metal may be to maintain a 'ringing' or even a 'tinkling' tone; from the wood we get a 'dull' or 'woody' quality. There are however other conditions to be presently referred to. To show the strength of the octave harmonic in a good pianoforte you will rarely find the tuner adjust the pitch note C (a) to its corresponding tuning-fork.

He prefers the middle C (b) an octave lower, because its first upper partial (c) beats, for a certain space of tune, more distinctly with the fork than the fundamental with which it is in unison. The scheme of strengthening the octave harmonic by an additional octave string is certainly a work of supererogation! But one very important factor in pianoforte tone is the hammer, both in its covering and in its striking place against the string. Helmholtz shows that a soft hammer causes softer or rounder tone because the greater continuity of contact of the soft material damps the very high upper partials, while the less continuity of contact of a hard-surfaced hammer allows small section's of the string to sound on. Strength of blow causes loudness by increasing the amplitude or greater vibrating excursion of the string, while it also expends more energy and increases the number of upper partials in the tone. Weakness of blow is, of course, of reverse influence. The striking-place, or point of contact of hammer and string, affects the tone variously. Experience teaches that it should be upon a nodal point, although many pianoforte makers neglect an accurate adjustment of the striking line, to the detriment of purity of tone. If the string could be struck exactly at the half of its length between the bridges, a kind of clarinet tone of great beauty would be obtained. On the other hand, by striking very near the wrestplank bridge, and thus favouring the very high partials at the expense of the lower ones, an approximation to the oboe tone would be gained. The so-called 'Lute' stop, in the harpsichord, is a practical illustration of this change of quality. The best fundamental tone in combination with the best sounding partials is obtained at the eighth of the string; at the ninth the tone hardens by diminution of the power of the prime, which is proved by the hammer requiring more 'toning' or softening. The high upper partials continue to come into greater prominence as we ascend to the tenth and higher, for which reason, to get brighter trebles, pianoforte makers have adopted the device of bringing the striking-place inwards as they ascend, with a loss of equality of tone. In the old keyboard instruments which preceded the pianoforte, and indeed in the early pianofortes, no attention was paid to accuracy of striking-place. In Harpsichords and spinets the strings were usually touched somewhere between the half and the tenth of the length; but the small diameter of the strings favoured the due formation of agreeable upper partials.^[3]

The framing and weight of stringing have much to do with the bars attached to the under side of the belly or soundboard of a pianoforte. These bars cross the direction of the grain of the Spruce Fir of which the belly is made, and promote the elasticity of this most important tone reinforcer. Without the Resonance table the strings would offer scarcely any sound, and without the elasticity gained by the bars their high upper partials would be imperfectly reflected, or immediately lost. The hard wood bridge carries the complete pulsations of the strings to the soundboard by alternating greater and less pressures. On the whole no other musical instrument is capable of the infinite variety of the tone qualities of the pianoforte, as various as the wonderfully nervous touch of the ends of the fingers of the player, which differs in every individual so that no two persons produce quite the same tone from the pianoforte unless they may be said to agree in the bad tone obtained by inelastic thumping.

We can compare, although remotely, the violin with the pianoforte in some of the fundamental principles of tone-production, but in many respects these instruments are very different. For instance, in the tone-production, the string clings to the bow until it is suddenly detached, when it rebounds and is caught by the bow again. Thus a peculiar vibrational form ensues, in which, according to Helmholtz, the prime or fundamental tone is stronger than in the pianoforte, while the first upper partials are comparatively weak. The sixth to the tenth are much stronger, which gives the bowed instruments their cutting character—the 'scolding violins,' as old Thomas Mace called them when they were beginning to supersede the viols and lutes. Any scratching of the bow is immediately shown by sudden jumps or displacements of the compound figure of vibration. The form of this figure is however tolerably independent of the place of bowing, usually at about one-tenth of the length of the string. The quality becomes somewhat duller as we approach the fingerboard, and brighter as we approach the bridge, at least for forte passages. We have resemblances to the pianoforte in the pressure of stopping in the violin by the finger, in the pianoforte by a firm wrestplank bearing; by this power the production and continuity of the upper partials is assisted and maintained. The 'bass bar' in the violin answers to the more complex barring of the piano, by screwing the belly up to the required pitch of elasticity for the reinforcement of the upper partials. Lastly, the bowing has some analogy to the touch of the pianoforte player; in that quality of individuality which extinguishes or subordinates the mechanical in performance.

Recent researches have proved that the orchestral division of wood and brass in wind instruments is nominal, or nearly nominal, only. The material affects the tone of those instruments by the rigidity or elasticity which it offers for enclosing columns of air. The cause of the difference of the quality of tone is the shape of the air column as it approximates to a cylindrical or conical form, and is wide or narrow for the production of the proper tones; the upper partials as determining the quality, and in combinations as harmonics. The production of the tone—whether by double reed (as in the oboe), by single reed (as in the clarinet), or by embouchure (as in the flute); the hypothetical air reed in flue organ pipes, and the action of the lips as vibrating membranes in the cupped mouthpieces of horns, trumpets, trombones, etc.—has its place in the determination of quality; so much so, that to preserve the colour of tone in the orchestra, clarinets and oboes have not been improved, as the flute has been, lest their distinctive qualities of tone should be destroyed. But orchestral qualities, considered as a whole, do slowly change. It would not now be possible to restore the orchestral colouring of Handel or Bach.

The most strident reed-tone is heard in the harmonium. In that variety called the American organ, the force of the high upper partials engendered by the action of the reed, is qualified by altering its position and form. It is impossible in a dictionary article to carry out the discussion of various qualities of tone, even as far as the subject is already known; the writer can only refer the inquirer to the best existing sources of our knowledge: to the great work of Helmholtz already referred—to especially in Mr. Ellis's translation, which contains appendices of great importance; to the writings of Dr. Stone and M. Mahillon on wind instruments; to Mr. Walter Broadwood's translation of an essay by Theobald Boehm, on the flute, and to some interesting articles 'In the Organ and in the Orchestra,' written by Mr. Hermann Smith, and published in 'Musical Opinion.' The writer can only lay claim to independent investigation as regards the pianoforte and its congeners. [See Timbre.]

[ A. J. H. ]

1. We abstain from reference to the much-debated combination or differential tones which the ear can perceive lower in pitch than the fundamental.
2. The peculiar, touching, character of the Æolian harp harmony is determined by the frequent presence of the Harmonic Seventh, an interval rejected in our music and replaced by sharper dissonant sevenths oi on entirely different tone character.
3. The effect of the striking is due, generally, to the intensity of motion of the simple vibrations, and the corresponding increase or decrease of the partials, at the point of excitement by the hammer, thus affecting the composition of the musical tone. Helmholtz (Ellis) p. 123.