Informational Site NetworkInformational Site Network
Privacy
 
  Home - Music Terms - Music Lessons - How to Sing - Music History - Singing Choirs - Children Songs - The Voice - Advice for Singers
   Lyrics: by Arist - (HED) P.E. to BREAKING POINT - BRIAN MCFADDEN to FINGERTIGHT - FIONA APPLE to JUSTIN GUARINI - JUSTIN TIMBERLAKE to MURPHY LEE - MUSE to SARINA PARIS - SASH to THREE 6 MAFIA - THREE DAYS GRACE to ZWAN

Most Viewed

Terms Relating To Vocal Music
Dynamics
Tempo (_continued_)
Embellishments
Scales (_continued_)
Symbols Of Music Defined
Terms Relating To Forms And Styles
Musical Instruments
Chords Cadences Etc
Measure


Least Viewed

Terms Relating To Forms And Styles (_continued_)
Terminology Adoptions 1907-1910
The History Of Music Notation
Auxiliary Words And Endings
Rhythm Melody Harmony And Intervals
Scales
Miscellaneous Terms (_continued_)
Symbols Of Music Defined Part Two
Abbreviations Signs Etc
Terminology Reform


Random Music Terms

Tempo (_continued_)
Scales
Terminology Reform
Some Principles Of Correct Notation
Chords Cadences Etc
Symbols Of Music Defined Part Two
The History Of Music Notation
Tempo
Terms Relating To Vocal Music
Dynamics



Acoustics





NOTE:--It is usually taken for granted that the student of
music is familiar with the significance of such terms as
over-tone, equal temperament, etc., and with principles
such as that relating to the relation between vibration rates
and pitches: the writer has in his own experience found,
however, that most students are not at all familiar with such
data, and this appendix is therefore added in the hope that a
few facts at least regarding the laws of sound may be brought
to the attention of some who would otherwise remain in entire
ignorance of the subject.

1. Acoustics is the science which deals with sound and the laws of its
production and transmission. Since all sound is caused by vibration,
acoustics may be defined as the science which treats of the phenomena
of sound-producing vibration.

2. All sound (as stated above) is produced by vibration of some sort:
strike a tuning-fork against the top of a table and see the vibrations
which cause the tone, or, if the fork is a small one and the vibrations
cannot be seen, hold it against the edge of a sheet of paper and hear
the blows it strikes; or, watch one of the lowest strings of the piano
after striking the key a sharp blow; or, look closely at the heavier
strings of the violin (or better still, the cello) and watch them
oscillate rapidly to and fro as the bow moves across them.

The vibrating body may be a string, a thin piece of wood, a piece of
metal, a membrane (cf. drum), the lips (cf. playing the cornet), the
vocal cords, etc. Often it is a column of air whose vibrations give rise
to the tone, the reed or other medium merely serving to set the air in
vibration.

3. Sound is transmitted through the air in somewhat this fashion: the
vibrating body (a string for example) strikes the air-particles in its
immediate vicinity, and they, being in contact with other such
air-particles, strike these others, the latter in turn striking yet
others, and so on, both a forward and backward movement being set up
(oscillation). These particles lie so close together that no movement at
all can be detected, and it is only when the disturbance finally reaches
the air-particles that are in contact with the ear-drum that any effect
is evident.

This phenomenon of sound-transmission may perhaps be made more clear by
the old illustration of a series of eight billiard balls in a row on a
table: if the first ball is tapped lightly, striking gently against ball
number 2, the latter (as well as numbers 3, 4, 5, 6, and 7) will not
apparently move at all, but ball number 8 at the other end will roll
away. The air-particles act upon each other in much this same fashion,
the difference being that when they are set in motion by a vibrating
body a complete vibration backward and forward causes a similar
backward and forward movement of the particles (oscillation) instead
of simply a forward jerk as in the case of the billiard balls.

Another way of describing the same process is this: the vibration of
some body produces waves in the air (cf. waves in the ocean, which carry
water forward but do not themselves move on continuously), these waves
spread out spherically (i.e. in all directions) and finally reach the
ear, where they set the ear-drum in vibration, thus sending certain
sound-stimuli to the nerves of hearing in the inner ear, and thus to the
brain.

An important thing to be noted in connection with sound-transmission is
that sound will not travel in a vacuum: some kind of a medium is
essential for its transmission. This medium may be air, water, a bar of
iron or steel, the earth, etc.

4. The rate at which sound travels through the air is about 1100 feet
per second, the rapidity varying somewhat with fluctuations in
temperature and humidity. In water the rate is much higher than in air
(about four times as great) while the velocity of sound through other
mediums (as e.g., steel) is sometimes as much as sixteen times as
great as through air.

5. Sound, like light, may be intensified by a suitable reflecting
surface directly back of the vibrating body (cf. sounding board); it may
also be reflected by some surface at a distance from its source in such
a way that at a certain point (the focus) the sound may be very clearly
heard, but at other places, even those nearer the source of sound, it
can scarcely be heard at all. If there is such a surface in an
auditorium (as often occurs) there will be a certain point where
everything can be heard very easily, but in the rest of the room it may
be very difficult to understand what is being said or sung.

Echoes are caused by sound-reflection, the distance of the reflecting
surface from the vibrating body determining the number of syllables that
will be echoed.

The acoustics of an auditorium (i.e., its hearing properties) depend
upon the position and nature of the reflecting surfaces and also upon
the length of time a sound persists after the vibrating body has
stopped. If it persists longer than 2-1/4 or 2-1/3 seconds the room will
not be suitable for musical performances because of the mixture of
persisting tones with following ones, this causing a blurred effect
somewhat like that obtained by playing a series of unrelated chords on
the piano while the damper-pedal is held down. The duration of the
reverberation depends upon the size and height of the room, material of
floor and walls, furniture, size of audience, etc.

6. Sound may be classified roughly into tones and noises although
the line of cleavage is not always sharply drawn. If I throw stones at
the side of a barn, sounds are produced, but they are caused by
irregular vibrations of an irregularly constructed surface and are
referred to as noise. But if I tap the head of a kettle-drum, a
regular series of vibrations is set up and the resulting sound is
referred to as tone. In general the material of music consists of
tones, but for special effects certain noises are also utilized (cf.
castanets, etc.).

7. Musical tones have three properties, viz.:

1. Pitch.

2. Intensity.

3. Quality (timbre).

By pitch is meant the highness or lowness of tone. It depends upon
rate of vibration. If a body vibrates only 8 or 10 times per second no
tone is heard at all: but if it vibrates regularly at the rate of 16 or
18 per second a tone of very low pitch is heard. If it vibrates at the
rate of 24 the pitch is higher, at 30 higher still, at 200 yet higher,
and when a rate of about 38,000 per second has been reached the pitch is
so high that most ears cannot perceive it at all. The highest tone that
can ordinarily be heard is the E[flat] four octaves higher than the
highest E[flat] of the piano. The entire range of sound humanly audible
is therefore about eleven octaves (rates 16-38,000), but only about
eight of these octaves are utilized for musical purposes. The tones of
the piano (with a range of 7-1/3 octaves) are produced by vibration
rates approximately between 27 and 4224. In the orchestra the range is
slightly more extended, the rates being from 33 to 4752.

Certain interesting facts regarding the relation between vibration-rates
and pitches have been worked out: it has been discovered for instance
that if the number of vibrations is doubled, the pitch of the resulting
tone is an octave higher; i.e., if a string vibrating at the rate of
261 per second gives rise to the pitch c', then a string one-half as
long and vibrating twice as rapidly (522) will give rise to the pitch
c'', i.e., an octave higher than c'. In the same way it has been found
that if the rate is multiplied by 5/4 the pitch of the tone will be a
major third higher; if multiplied by 3/2, a perfect fifth higher,
etc. These laws are often stated thus: the ratio of the octave to the
fundamental is as two is to one; that of the major third as five is to
four; that of the perfect fifth as three is to two, and so on through
the entire series of pitches embraced within the octave, the ratio
being of course the same for all octaves.

9. The intensity (loudness or softness) of tones depends upon the
amplitude (width) of the vibrations, a louder tone being the result of
vibrations of greater amplitude, and vice versa. This may be verified by
plucking a long string (on cello or double-bass) and noting that when
plucked gently vibrations of small amplitude are set up, while a
vigorous pluck results in much wider vibrations, and, consequently, in a
louder tone. It should be noted that the pitch of the tone is not
affected by the change in amplitude of vibration.

The intensity of tones varies with the medium conveying them, being
usually louder at night because the air is then more elastic. Tone
intensity is also affected by sympathetic vibrations set up in other
bodies. If two strings of the same length are stretched side by side and
one set in vibration so as to produce tone the other will soon begin to
vibrate also and the combined tone will be louder than if only one
string produced it. This phenomenon is the basis of what is known as
resonance (cf. body of violin, resonance cavities of nose and mouth,
sounding board of piano, etc.).

10. Quality depends upon the shape (or form) of the vibrations which
give rise to the tone. A series of simple vibrations will cause a simple
(or colorless) tone, while complex vibrations (giving rise to overtones
of various kinds and in a variety of proportions) cause more
individualistic peculiarities of quality. Quality is affected also by
the shape and size of the resonance body. (Cf. last part of sec. 9
above.)

11. Practically every musical tone really consists of a combination of
several tones sounding simultaneously, the combined effect upon the ear
giving the impression of a single tone. The most important tone of the
series is the fundamental, which dominates the combination and gives
the pitch, but this fundamental is practically always combined with a
greater or less number of faint and elusive attending tones called
overtones or harmonics. The first of these overtones is the octave
above the fundamental; the second is the fifth above this octave; the
third, two octaves above the fundamental, and so on through the series
as shown in the figure below. The presence of these overtones is
accounted for by the fact that the string (or other vibrating body) does
not merely vibrate in its entirety but has in addition to the principal
oscillation a number of sectional movements also. Thus it is easily
proved that a string vibrates in halves, thirds, etc., in addition to
the principal vibration of the entire string, and it is the vibration of
these halves, thirds, etc., which gives rise to the harmonics, or
upper partials as they are often called. The figure shows Great C
and its first eight overtones. A similar series might be worked out from
any other fundamental.


It will be recalled that in the section (10) dealing with quality the
statement was made that quality depends upon the shape of the
vibrations; it should now be noted that it is the form of these
vibrations that determines the nature and proportion of the overtones
and hence the quality. Thus e.g., a tone that has too large a
proportion of the fourth upper partial (i.e., the third of the
chord) will be reedy and somewhat unpleasant. This is the case with
many voices that are referred to as nasal. Too great a proportion of
overtones is what causes certain pianos to sound tin-panny. The tone
produced by a good tuning-fork is almost entirely free from overtones:
it has therefore no distinctive quality and is said to be a simple
tone. The characteristic tone of the oboe on the other hand has many
overtones and is therefore highly individualistic: this enables us to
recognize the tone of the instrument even though we cannot see the
player. Such a tone is said to be complex.

12. The mathematical ratio referred to on page 134, if strictly carried
out in tuning a keyboard instrument would cause the half-steps to vary
slightly in size, and playing in certain keys (especially those having a
number of sharps or flats in the signature) would therefore sound out of
tune. There would be many other disadvantages in such a system, notably
the inability to modulate freely to other keys, and since modulation is
one of the predominant and most striking characteristics of modern
music, this would constitute a serious barrier to advances in
composition. To obviate these disadvantages a system of equal
temperament was invented and has been in universal use since the time
of Bach (1685-1750) who was the first prominent composer to use it
extensively. Equal temperament means simply dividing the octave into
twelve equal parts, thus causing all scales (as played on keyboard
instruments at least) to sound exactly alike.

To show the practicability of equal temperament Bach wrote a
series of 48 preludes and fugues, two in each major and two
in each minor key. He called the collection The Well-tempered
Clavichord.

13. Various standards of pitch have existed at different times in the
last two centuries, and even now there is no absolute uniformity
although conditions are much better than they were even twenty-five
years ago. Scientists use what is known as the scientific standard
(sometimes called the philosophic standard), viz., 256 double
vibrations for middle C. This pitch is not in actual use for musical
purposes, but is retained for theoretical purposes because of its
convenience of computation (being a power of 2). In 1885 a conference of
musicians at Vienna ratified the pitch giving Middle C 261 vibrations,
this having been adopted by the French as their official pitch some 26
years before. In 1891 a convention of piano manufacturers at
Philadelphia adopted this same pitch for the United States, and it has
been in practically universal use ever since. This pitch (giving Middle
C 261 vibrations) is known as International Pitch.

Concert pitch is slightly higher than International, the difference
between the two varying somewhat, but being almost always less than
one-half step. This higher pitch is still often used by bands and
sometimes by orchestras to give greater brilliancy to the wind
instruments.

REFERENCES

Lavignac--Music and Musicians, pp. 1-66.

Broadhouse--The Student's Helmholz.

Helmholtz--Sensations of Tone.

Hamilton--Sound and its Relation to Music.

NOTE:--For a simple and illuminating treatment of the subject
from the standpoint of the music student, the books by
Lavignac and Hamilton are especially recommended.





Next: Terminology Reform

Previous: Musical Instruments



Add to del.icio.us Add to Reddit Add to Digg Add to Del.icio.us Add to Google Add to Twitter Add to Stumble Upon
Add to Informational Site Network
Report
Privacy
SHAREADD TO EBOOK


Viewed 2338