INTENSITY OF SOUNDS.

199

stimulation. The effect, at a given point, takes the character of pungency, like the action of ammonia on the nose, or a smart stroke on the skin. A loud speaker is exciting. The rattle of carriages, the jingle of an iron work, the noise of a cotton mill, the ringing of bells close to the ear, the discharge of musketry and ordnance, are all exciting from their intensity; to fresh and vigorous nerves plunged into them after quietness, these noises give pleasure. They may be described, however, as a coarse excitement; there is a great cost of tear and wear of nerve for the actual satisfaction.

The intensity, rising beyond a certain pitch, turns to pain. The screeching of a parrot-house, the shrill barking of the smaller species of dogs, the whistling in the fingers practised by boys in the streets, the screaming of infants, are instances of painful pungency. The sharping of a saw, and the scratching of a piece of glass, yield an intense shrill note. In most of these cases, we must suppose an element of dissonance as well as a great and smarting intensity. The only criterion of marked dissonance, as opposed to mere pungency, is the offence given to the ear under all conditions, and not merely under fatigue or exhaustion.

The suddenness of sounds, by the abrupt transition, aggravates their intensity on the general principle of Relativity. If unexpected, they produce the discomposure usually attending a breach of expectation.

7. Volume or Quantity.-This means the sound coming from a sounding mass of great surface or extent. The waves of the many sounding sea,' the thundery discharge, the howling winds, are voluminous sounds. A sound echoed from many sides is voluminous. The shout of a great multitude is impressive from the volume. Grave sounds, inasmuch as they require a larger instrument, are comparatively voluminous.

Whether sounds be sweet or indifferent, their multiplication has an agreeable effect on the ear. The sensation is extended in volume or amount without the waste of nervous power accompanying great pungency. Both physically and

mentally, these sounds conform to the laws of massive sensation.

If a sound is intrinsically harsh or grating, or if painful from intensity, the increase in volume will be an increase of pain; as in machinery. The braying of the ass combines the harsh and the voluminous.

8. Pitch or Tune.-By pitch is meant the acuteness or graveness of a sound, as determined by the ear, and resolvable into the rate of vibration of the sounding body, or the number of vibrations in a given time. The gravest sound audible to the human ear is (according to Helmholtz) 16 vibrations a second; the highest audible sound corresponds to 38,000 vibrations a second; being a compass of eleven octaves. One of the deepest tones in use on orchestra instruments is the E of the double bass, giving 411 vibrations a second. The highest note of the orchestra (D of the piccolo flute) is 4752 vibrations. (Helmholtz : Tyndall's Lectures on Sound, p. 72). The practical range is thus about seven octaves. At the upper limit of hearing, persons differ as much as two octaves; the squeak of the bat and the sound of a cricket are unheard by some ears.

A sound of uniform pitch is a musical note. In the fact of uniform continuance, there is a pleasure of the nature of harmony. It is only such sounds that can be farther combined into musical harmonies.

ear.

Although, in music, less intervals than a semitone are not admitted, the ear can distinguish still smaller differences. A quarter of a tone makes a marked difference to an ordinary A good musician can distinguish two tones whose vibrations are as 1149 to 1145, sounded after each other, and even a smaller difference if they are sounded together. Two pitchforks whose number of vibrations per second are 1209 and 1210, sounded simultaneously, can be distinguished by a first-rate ear.

9. The waxing and waning of sound. The gradual increase or diminution of the loudness of a sound, is one of the effects introduced into musical composition, owing to the

HARMONY AND DISCORD.

201

power it has to impart additional pleasure. The howling or moaning of the wind has sometimes this character, and produces a deep impression upon all minds sensitive to sound. The dying away of sound is especially noted as touching: 'that music hath a dying fall.' It may be, that a muscular feeling enters into this sensation: the gradually increased or relaxed tension of the muscles of the ear being a probable accompaniment of the increase or diminution of loudness. We cannot affirm, however, that it may not be due to the auditory nerves alone. When the pitch is gradually changed, as well as the degree, we have a farther modification introduced into musical composition, but apt to degenerate into the 'whine' or 'sing-song.' In the notes of birds, we may trace this effect; in the execution of accomplished singers, in the violin and other instruments, and in the cadences of a musical orator, we may likewise observe it; in all cases telling powerfully.

10. Harmony and Discord.-The concurrence of two or more sounds may be pleasing or unpleasing, irrespective of their character individually. The pleasurable concurrence is called Harmony. It is dependant upon the numerical relationship of the vibrations of the two sounds. Simple ratios, as 1 to 2 (octave), 2 to 3 (fifth), 3 to 4 (fourth), 4 to 5 (major third), 5 to 6 (minor third), are harmonious in the order stated. All these are admissible in musical composition, and are termed chords. The combination 8 to 9 (a single tone) is a dissonant combination; 15 to 16 (a semi-tone) is a grating discord.

It has already been mentioned that an individual sound whose character is sweetness, is already a harmony, or concord of many sounds; the main tone being combined with overtones. In music, these sounds are still farther combined, according to the general laws of harmony.

The pleasure of harmony is a wide-spread fact of the human mind; it extends to sight as well as to hearing, and is not wanting in the inferior senses; we may have harmonizing or discordant tastes. In the higher emotions, a concurrence

may be either harmonious or discordant. The foundation of the pleasure is probably the same throughout; it is a general principle whereby mental states are regarded as either cooperating, or conflicting, with each other; in the one case, economizing nervous power and bringing pleasure; in the other, wasting power and causing pain.

11. Timbre. This means the difference between sounds, otherwise the same, proceeding from different materials, instruments, or voices. We recognize a qualitative difference between the flute and the violin, or between the trumpet and the clarionet; we can distinguish between one violin and another, and between different voices sounding the same notes with the same intensity. These differences are now explained by the presence of auxiliary upper tones in all instruments; which tones vary with the material and the instrument. It is supposed that perfectly pure tones identical as regards pitch and intensity, would be undistinguishable, whatever might be their source.

12. Articulate sounds.-Of articulate sounds, some have a character so peculiar that our discrimination of them is no surprise. The hissing sound of s, the burring of the r, the hum of the m, are well marked modes of producing variety of effect. We can understand how each should impart a different kind of shock to the nerve of hearing. So we can see a reason for distinguishing the abrupt sounds p, t, k from the continuous or vocal sounds b, d, and g, and from the same sounds with the nasal accompaniment m, n, ng. It is not quite so easy to explain the distinction of shock between the labials, dentals, and gutturals; still, if we compare p (labial), with k (guttural), we can suppose that the stroke that gives the k is harder than the other.

The vowel sounds are explained by the over-tones (octaves) concurring with each fundamental tone, and varying according to the resonance of the mouth, the form of which is altered for each vowel. When the ground tone is heard nearly alone, the sound has the character of u (full). The o has, along with the ground tone, the next octave audibly combined. The a

ARTICULATE SOUNDS.

203

(ah) is characterized by the marked presence of the very high

octaves.

The same principle is applied to explain differences in the consonant sounds; but as respects these, there are other palpable distinctions such as we have alluded to above.

Some persons are distinguished by their nice discrimination of articulate sounds. If the foregoing theory be correct, a good ear for musical notes should be also a good ear for articulation, seeing that the articulate sounds involve composite musical tones. An ear for pitch is thus the basis both of music and of speech. Strictly speaking, however, this applies to the vowels. The discrimination of consonants may depend on other qualities of the ear; a circumstance requiring to be adverted to, seeing that, in point of fact, the good musical ear is not always a good articulate ear. The sense of Time is not confined to any organ or any class of feelings; but it may attain to great perfection in hearing.

13. The perception of distance can result from nothing but experience. I quote from Longet. 'As soon as the organ presents a sensibility and a development sufficient for discerning easily the relative intensity of two consecutive sounds, nothing farther is necessary in order to acquire the notions of distance and direction of the body from which the sonorous waves emanate. In fact, if a sound is already known to us, as in the case of the human voice, or an instrument, we judge of its distance by the feebleness of its impression upon the nerve of hearing; if the sound is one whose

* The following is Helmholtz's table for the leading vowel sounds :GroundVowel. Tone. 2nd.

3rd. weak

4th.

5th.

6th.

7th.

(weak)

o (oh) strong strong (weak)

e (get) strong middling strong (weak) (weak)

i (bit)

weaker strong (very weak) strong (middling)

a (ah) strong (weak) weak middling stronger stronger stronger

than 3 and 4.

The parentheses denote that the tones they inclose are not absolutely neces sary to the making of the special vowel-sound.