Yeditepe University Fall 2015 A SHORT INTRODUCTION TO SOUND AND MUSIC by NAMIK ÇIBLAK Department Of...

Yeditepe UniversityFall 2015

A SHORT INTRODUCTION TOSOUND AND MUSIC

byNAMIK ÇIBLAK

Department Of Mechanical Engineering

N. Ciblak, Dept. of Mechanical Engineering, Yeditepe University – Fall 2015 2

WHAT IS SOUND?• Physical Sound: Vibrations of solids, fluids, and other fluid-like systems in form of

elastic waves.

– In solids, the elastic waves are those of structural deformations,

– whereas in fluids they are seen as pressure, and, if compressible, density fluctuations.

– In normal usage, the term sound refers to that in fluids, especially air, due to our anthropocentric tendencies, despite the fact that humans can hear underwater, too.

• Physiological Sound: Physical and chemical response in many animals induced by pressure fluctuations in air/water.

– Originates in outer ear, the external receiver/interface device.

– Progresses through inner ear, pre-processor responsible for transducing the pressure signal to vibrations of ear membrane, then to the fluid pressure waves in cochlea.

– Ends at neurons responsible for transducing the fluid waves into electrical signals that are eventually sent to the brain for recognition. This stage also involves some pre-processing and feedback.

• Psychological Sound: The sensory sound as perceived, recognized and processed by human brain, along with all other accompanying psychological effects.


BASIC TYPES OF WAVE PROPAGATION– Longitudinal waves: Wave propagates in the same direction as the vibrating particles. The

sound in fluids exhibits this characteristic.

– Transverse waves: Wave propagates in a direction perpendicular (transverse) to that of the vibrating particles. The waves in a transversely vibrating string or membranes are examples of this kind.

Travel direction

Particle vibration

Travel direction

Particle vibration

Combination of these two modes are also possible, e.g. in solids.

Travel direction


PHYSICAL SOUND IN AIR

• Sound travels along infinitely many paths.• Speed of sound, c, in air is a function of temperature.• Sound in hot air travels faster in that in cold air.• Sound signals traveling in paths labelled as 1 and 2 arrive at the target at the same

time although path 2 is longer.• The sound travels much faster in solids.• Therefore, the time of arrival through path 3 is also the same.• All sounds arriving from various paths at the same time are added at the target.

𝑐≅ 20√𝑇+273T: temperature in °C

m/s

Hot air

Cold air

For dry air

1

2

3

N. Ciblak, Dept. of Mechanical Engineering, Yeditepe Faculty of Engineering Seminars – Fall 2011

5

WHAT IS ACOUSTICS?

VibrationSource

Physical PsychologicalPhysiological

?

Acoustics Psychoacoustics

Sound: pressure waves

Complex auditory functionsWith less known feedback mechanisms


6

WE HEAR LESS THAN IS• What we hear is less than what actually happens outside of us.• For our species, audible sound is limited to a certain range of frequencies.

Infrasonic Sonic Ultrasonic

~ 15 – 20 Hz ~ 20 kHz

• Starting from the outer ear; every organ, every part, every tissue of the auditory system behaves as an analog filter.

• Net effect is a complex equalizer: some frequencies amplified, others attenuated or lost.

• For soft sounds the filter is more or less linear, whereas for louder sounds it becomes nonlinear.

• Audible sound is also limited by intensity:– Too low intensity inaudible– Too High intensity inaudible, physical damage

LowFrequency

HighFrequency


7

BUT, WE ALSO HEAR MORE!• Yes, what we hear is also more than what actually happens outside of us!• Paradoxical? Not quite so …• Nonlinear amplifier effects:

-1

-0.5

0

0.5

1

-0.5

0

0.5

1

1.5

2

2.5

NonlinearAmplifier

Original Pure Sinusoidal Signal As Received by Brain

• Aural harmonics: If the loudness of a sound at frequency f is gradually increased, additional frequencies (2f, 3f, …) are heard – though nonexistent!

• Missing Fundamentals: Creation of non-existent frequencies due to active feedback from brain. If two sounds at pure f1 and f2 frequencies are given, humans also hear other frequencies such as |f1 - f2|, |f1 + f2|, …

• As we are susceptible to optical illusions, we can also experience many such auditory illusions. Mechanism is not well known.

• In pathological cases, feedback may cause tinnitus (kulak çınlaması) or non-existent sounds (gaipten sesler?).


8

SOUND INTENSITY• Objective measure: Intensity, I in

watts/m2. Signal power per incident area.

• Better objective measure: Sound Pressure Level, SPL, or Sound Intensity Level, SL in dB

Source IntensityW/m2 dB

Threshold of Hearing 10-12 0Quiet Library 10-8 40Conversation 10-6 60Hair Dryer 10-4 80Live Rock Concert(Threshold of Feeling)

1 120)log(10

refIISL 1210refI

• In a rock concert, the sound power level is 1012 (trillion) times greater than the weakest sound we can hear! Short cut to deafness …

• A 3-dB increase in sound level means twice an increase in intensity.• There are other objective measures, too.


9

ON LOUDNESS AND PITCH• Intensity and frequency are objective, physical measures.• Loudness and pitch are psychoacoustic terms subjective.• Loudness is the perceived sound intensity.• Pitch is the perceived frequency of a pure or combination tone.• They are determined by human experiments.• If sounds of same intensity are presented to a human at different

frequencies, he judges them to be of different loudness.

• The red points in the graph represents sounds with distinct intensities and frequencies.

• Yet, for an average human, their loudness is the same!

• Such curves are called equal loudness curves.

73

52

30

1820

0

20

40

60

80

10 100 1000 10000Frequency (Hz)

SL (d

B)


10

WHAT IS MUSIC?• A coordinated sequence (or simultaneous sequences) of

sounds of predetermined frequencies.• These predetermined frequencies

– are the building blocks called the NOTES– show cultural dependency

• Anatolian music have more notes than the European.• Some cultures (Indian, Chinese, Arabic, …) have even more.• Having more notes does not mean better music.• Having less notes does not mean better music.• It is the relative differences (distances) between the notes that

is important, not the absolute value of frequencies.


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NOTES AND HARMONY• Ideally, a note is a sound of certain singular frequency.• A vibration with a frequency that is an integral multiple of the

frequency of another vibration is called a HARMONIC of the latter (or of each other).

• Thus, every note has infinitely many harmonics.– Example: a pure 440 Hz sound is a harmonic of 220 Hz or 110 Hz sound

• Real notes are almost always accompanied by its harmonics with lesser intensities.

• For some reason, humans have an innate ability of identifying the harmonics of a pure sound.

• Further, humans tend to like hearing a sound together with its harmonics (HARMONY).

• “Harmony” makes us feel that things are “OK”.


12

HARMONY IN MUSIC• The term “harmony” may mean more in music.• Two or more notes, not integral multiples of each other,

may still sound nice when played simultaneously.• With proper rhythm, such harmonic sequences make

us feel more satisfied, or not irritated.• Do you recall the uneasiness, unsettledness, hunger

for “order” that we feel while an orchestra prepares for the performance, as players try to tune their instruments without regard for what others are doing?

• Why do protesters or sports fans try to chant in unison, in a rhythmic fashion?

• Why do we feel tired at the end of a casual and crowded party?


13

ANIMALS, ANCIENTS & HARMONY• According to some research:

– Human infants are able to recognize harmonics– Humans of age 4 – 9 are somewhat unable– Adults human musicians (all levels) can, others may not be able to do so– Mice cannot, (Sığırcık kuşu) can, …

• How did the ancients discover “frequencies”?– They did not!– But, they were aware of harmonics.– They probably experimented on strings,

especially on an ancient musical instrumentwith only one string.

– They discovered that a string of half the lengthof another gave the next harmonic of the latter.

– Pythagoreans thought, as with 2/1 ratio; 3/2, 4/3, …string lengths should also sound “good” with the base length.

– They were not too far from what we have today!

2L L

tie

tie

no tienails

A crude experiment


14

CIBLAKEAN HARP Tuning Knob

Features• Single string, one tension• All notes are tuned at once• Rollers can be equipped with

push-down mechanisms to prevent axial interactions

• Started seriously considering a patent application

x

La2 La3 La4

Rollers

Tied End

LkT

Lf 1

21 0

Lowest free vibration frequency of a wire (Hz)

L

f

Lk 1


15

TEMPO AND RHYTHM• Tempo (Beat): speed of succession of elements.• Rhythm: regulation of what happens while the beats beat. It is a pattern or a

signature. Its alphabet is akin to Morse’s (silence, long, short, …)

• Rhythm exists in all art: music, painting, sculpture, architecture, …• More subtle in other arts than performance arts.• The most basic feature of music. One can change the tempo of a piece, but

the rhythm stays the same.• This is similar to what you hear from inside of a train. That “taka-tuka” sound

is the rhythm of the sound of wheels on rails. Its pattern stays the same even if the train goes faster.

• Without a rhythm, there is no music, despite efforts to the contrary.• We need rhythm, there is no escaping it!

BeatsRhythm

Measure ♪ ♪♪long short short Accent on first


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THE MELODY• A succession of notes chosen from a sequence.• The most, or equally, influential part of music after

rhythm.• It also exists in other arts, static or dynamic.• As there is melody in painting, there is color in music.• As there are tones in music, there are tones in

painting.• It has shades and contrasts.• It is the melody that invokes our psychological

sensation.


17

THE FORM• Why, in many cases, can we almost

immediately recognize a piece from Karadeniz?• Why is tango so singular?• Indian or chinese music?• Marches, Uzun Hava, Bozlak, Efe?

• Many things such as rhythm, sequences, styles, experience, … contribute to our ability to distinguish.

• This inherent distinctiveness is called the form.


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THE COMPOSITION• An arrangement of the elements.• Exists in all forms of art from writing to painting, to

music.• Determines the overall taste.• A higher level of creation.• Can be bad despite good elements.• In a composition, everything from rhythm to melodies

can change; simultaneously, momentarily, or sequentially.

• It is the house of creation!• As we teach our students: it has an introduction, a

body, and a conclusion.• It is what you want to say!


19

Do – Re – Mi?• The original syllabi for naming notes:

Do-Re-Mi-Fa-Sol-La-Si (Ti)

• In English notation, “Ti” is used instead of “Si”. The latter is reserved for the flat version.

• These names are used for singing the notes of melodies.• In western music alphabet letters are also used to name the

notes. Starting with “Do” these letters are:

C-D-E-F-G-A-B


20

The Origin of Do – Re – Mi• The original syllabi for naming notes are said to come from an old

(medieval?) Latin hymn or chant (church song). “Ut” was changed to “Do” and “Si” was added later, after “La”.

Ut queant laxisResonare fibrisMira gestorumFamuli tuorumSolve pollutiLabii reatumSancte Joannes

So that your servants may, with loosened voices, resound the wonders of your deeds, clean the guilt from our stained lips, O, Saint John!

Do let our voicesresonate most purely,miracles telling,far greater than many;so let out tongues belavish in your praises,Saint John the Baptist.

Original Latin Chant English Adaptation

Dost, duy sesimi,Reddediyor sensizliği.Mihnet kabulüdür,Fani müridinin,Solmasın yeter ki oLatif, güzel yüzün,Sinem de parelenmesin.

A Trial in Turkish

Namik CiblakJanuary 2016English Translation of the Latin Hymn


21

THE OCTAVE – WESTERN INTERVALSStarting

Frequencyf

EndingFrequency2f

Full Full Full Full FullHal

f

Hal

f

DO RE MI FA SOL LA SI DOC D E F G A B C

C#DI

D#EI

F#GI

G#AI

A#BI

• Eight basic musical notes: 2½ + 3½ full intervals = 12 half-intervals• Eight octave• Question: How do we divide an octave into twelve “equal” half-intervals?

• Wrong Way: half-interval length = (2f – f )/12 = f / 12.• Ancients: each note = m / n * f, where m and n are smallest possible

integers. For an octave m = 2, n = 1. To ancient numerologists whole numbers were of divine nature (esp. Pythagoreans).

• Modern Method: nth note = kn * f, where k = 21/12, n = 0,1,2,…,12This is called the “Equal Temperament” system.


22

THE EQUAL TEMPERAMENT SYSTEM• Frequencies of contemporary musical notes are based on the value of LA (A).• For some reason, the standard frequency value of LA, of the fourth octave, is decided

to be 440 Hz. Orchestras sometimes change this value slightly when necessary.• This sound is also used as the dial-tone in modern telephone systems.• Still today, there are musicians who tune to LA by listening to the dial-tone of the

standard phone network.• The LA notes of all the four octaves of a piano are thus determined as 110, 220, 440,

880 Hz.???• Curiously, the first two are also the frequencies of the two basic alternating current

systems used in the world. Hence, a sufficiently strong speaker, with adequate electronics, would have sounded a LA had it been connected to the AC outlet!

• All other notes can be found from a LA by constantly multiplying each previous note, starting from LA, by 21/12 = 1.059

La3 Sib Si Do Do# Re Re# Mi Fa Fa# Sol Lab La4

220 233.1 246.9 261.6 277.2 293.7 311.1 329.6 349.2 370.0 392.0 415.3 440

4/3 La3 = 293.3Pythagorean Perfects 3/2 La3 = 330.0 2/1 La3 = 440


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SCALES OR SEQUENCES (Dizi, Makam)

Do Re Mi Fa Sol La SiLabDo# Re# Fa# Sib

Sol Major

Key Note: (Karar) The note to which, normally, the melody periodically tends to. In Turkish folk music the key note has a very dominant role. An overwhelming majority of pieces ends exclusively on the key note. (Karadeniz is a strong exception)

KEY ()

Mi Major, Turk.

•When a melody contains notes only from a major sequence, it is felt to be moremerry, lively, march-like, heroic sounding, … (not always, of course)•In contrast, a piece in a minor sounds more solemn, tragic, depressive, moody, …•A majority of aşık pieces from Anatolian alevite tradition uses the Mi Major

sequence,from which, surprisingly, only six or seven notes are used in most of the melody.•Mi minor sequence is very common in both traditional and classical Turkish music.•Variations and mixings of all major and minor sequences are also found.•Sometimes, a piece may suddenly change both the key and the sequence.

Mi Major, West. Mi Minor

Do

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