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TA212 The Technology of Music Steve Wells. Producing Musical Sounds TA212: Block 3, Chapter 1.

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Presentation on theme: "TA212 The Technology of Music Steve Wells. Producing Musical Sounds TA212: Block 3, Chapter 1."— Presentation transcript:

1 TA212 The Technology of Music Steve Wells

2 Producing Musical Sounds TA212: Block 3, Chapter 1

3 TA212 - Block 3 - Chapter 1 - Producing Musical Sounds Musical Instruments instruments strings wind woodwind brass plucked bowed percussion tuned untuned electronic struck flute clarinet keyboard tuba recorder trumpet piano trombone guitar harp violin cello side drum tom xylophone tubular bells synthesiser

4 TA212 - Block 3 - Chapter 1 - Producing Musical Sounds Musical Instruments Something which produces sound –Compressions and rarefactions in the air Predictable output –Pitch –Volume –Rhythm Controllable by a player

5 TA212 - Block 3 - Chapter 1 - Producing Musical Sounds Sound Production Need to be able to put energy into the system (excitation) –No energy – no noise! Something to resonate –Primary vibrator provides pitch String, air column –Secondary vibrators The rest of the instrument

6 TA212 - Block 3 - Chapter 1 - Producing Musical Sounds Sound Excitation Putting in energy to make a sound –Blowing into a wind instrument –Plucking a string –Bowing a string –Beating a drum Energy in a burst –Transient sound Energy continuous –Sustained sound

7 TA212 - Block 3 - Chapter 1 - Producing Musical Sounds Nodes and Antinodes Waves can “interfere” producing locations where there is no change These locations are fixed despite the fact that the waves are moving A place where Nothing is changing is called a Node An Antinode is where something is changing

8 TA212 - Block 3 - Chapter 1 - Producing Musical Sounds Types of Node A place where Nothing is changing is called a Node Two types of Node: –A Pressure Node occurs where there is no change of pressure for example, at the open end of a wind instrument –A Displacement Node occurs where there is no displacement (movement) of the vibrating medium for example, at the bridge of a stringed instrument

9 TA212 - Block 3 - Chapter 1 - Producing Musical Sounds Standing Waves The sequence of nodes and antinodes form a standing wave When a string is vibrating: displacement node displacement antinode ANN

10 TA212 - Block 3 - Chapter 1 - Producing Musical Sounds Standing Waves The sequence of nodes and antinodes form a standing wave When an air column is is vibrating: displacement antinode displacement node AAN

11 Woodwind Instruments TA212: Block 3, Chapter 2

12 TA212 - Block 3 - Chapter 1 - Producing Musical Sounds Wind Harmonics open pipestopped pipe NOTE: A conical pipe (such as an oboe) behaves like a pipe open at both ends

13 TA212 - Block 3 - Chapter 1 - Producing Musical Sounds “Bernoulli” Principle Air blowing over a surface creates suction …either the air moves...…or the surface moves!

14 TA212 - Block 3 - Chapter 1 - Producing Musical Sounds Oboe Reed air

15 TA212 - Block 3 - Chapter 1 - Producing Musical Sounds Recorder Mouthpiece air Suction due to the Bernoulli Effect. The air stream passes to one side of the edge, is sucked onto the edge and overshoots. This repeats...

16 TA212 - Block 3 - Chapter 1 - Producing Musical Sounds Wind Pitch Length of the pipe determines the pitch –(also temperature) Change pitch by: –Changing the length Brass instruments –Finger holes Woodwind

17 TA212 - Block 3 - Chapter 1 - Producing Musical Sounds Wind Pitch Pitch of a pipe depends on two things: –Length (L) : shorter = higher –Speed of Sound (v) : higher temperature = higher For a pipe open at both ends: For a stopped pipe (open at one and closed at the other):

18 TA212 - Block 3 - Chapter 1 - Producing Musical Sounds Fingerholes Effective length depends on the position and size of the hole

19 TA212 - Block 3 - Chapter 1 - Producing Musical Sounds Fingerholes physical end of the pipe displacement antinodes no fingerhole small fingerhole large fingerhole The displacement antinodes are at different possible positions due to different end effects.

20 TA212 - Block 3 - Chapter 1 - Producing Musical Sounds Recorder Mouthpiece displacement antinode Due to end effects, the displacement antinode is effectively inside the air channel air

21 TA212 - Block 3 - Chapter 1 - Producing Musical Sounds End Correction Effective length of a pipe is greater than the physical length of the pipe. effective length physical length

22 TA212 - Block 3 - Chapter 1 - Producing Musical Sounds End Correction radius (r) end correction (e)

23 TA212 - Block 3 Question: Length of a Pipe A pipe stopped at one end sounds the note A 4 (440Hz) as its first harmonic. If the pipe has a diameter of 20mm, what is the physical length of the pipe? Assume the speed of sound to be 340m/s.

24 Brass Instruments TA212: Block 3, Chapter 3

25 What is a Brass Instrument Not always made of brass!! Key idea is the way the sound is made –Lip reed –Players lips vibrate within the mouthpiece to excite the air column –Similar to the way a reed excites the air column in and oboe or clarinet TA212 - Block 3 - Chapter 3 - Brass Instruments

26 Parts of a Brass Instrument TA212 - Block 3 - Chapter 3 - Brass Instruments

27 Types of Brass Instrument Mainly Cylindrical –Natural Trumpets and Trombones Mainly Conical –Horns Combination of Cylindrical and Conical –Trumpet –Cornet (A Cornet has a longer conical section than a Trumpet) TA212 - Block 3 - Chapter 3 - Brass Instruments

28 The Air Column The bell is open The mouthpiece behaves like a closed end However... –Fundamental not used (usually out of tune) –The flare on the bell raises the pitch of the lower harmonics –The mouthpiece lowers the pitch of the upper harmonics The effect is to get an almost complete harmonic series (the fundamental is missing) TA212 - Block 3 - Chapter 3 - Brass Instruments

29 Tuning Harmonics are used more than with woodwind –Bugle only uses harmonics Tuning –Slide –Valve –Finger holes like woodwind not used in modern orchestral instruments TA212 - Block 3 - Chapter 3 - Brass Instruments

30 Valves TA212 - Block 3 - Chapter 3 - Brass Instruments

31 Stringed Instruments TA212: Block 3, Chapter 3

32 TA212 - Block 3 - Chapter 1 - Producing Musical Sounds String Harmonics Many different standing waves The sounds they produce are the harmonics of the string.

33 TA212 - Block 3 - Chapter 1 - Producing Musical Sounds String Pitch Pitch of a string depends on three things: –Length (L) : shorter = higher –Tension (T) : tighter = higher –Mass per unit length ( ) : lighter = higher

34 TA212 - Block 3 Question: String Tension A Fender Stratocaster has a string length of 648mm. The sixth string (lowest pitch) has a mass per unit length of 6.79x10 -3 kg/m. It is tuned so that its first harmonic is E 2 (82.4Hz). What is the tension in the string? f 1 frequency Ttension Llength µmass per unit length

35 Violin Family Many medieval instruments were bowed –Rebec –Vielle The modern violin appears in late 17 th century Four sizes TA212 - Block 3 - Chapter 3 - Stringed Instruments Lowest noteTuned in ViolinG3G3 Fifths ViolaC3C3 Fifths CelloC2C2 Fifths Double BassE1E1 Fourths

36 Violin Bridge TA212 - Block 3 - Chapter 3 - Stringed Instruments

37 Lutes and Guitars Descended from arabic instrumets –Through Moorish Spain or, perhaps, the Crusades –“Lute” comes from “al‘ud” Plucked and Strummed Strings stretched along a neck –Usually fretted Many variations throughout the Middle and Far East –Long and short necks –“2” to “12 or more” strings TA212 - Block 3 - Chapter 3 - Stringed Instruments

38 Classical Guitar Modern form developed in 19 th –Torres developed the larger body and fan strutting –Tarrega and, later, Segovia showed what the instrument was capable of Six strings –E 3, A 3, D 4, G 4, B 4, E 5 TA212 - Block 3 - Chapter 3 - Stringed Instruments

39 Percussion TA212: Block 3, Chapter 5

40 TA212 - Block 3 - Chapter 5 - Percussion Drum Vibration Modes

41 TA212 - Block 3 - Chapter 5 - Percussion Drum Frequencies

42 TA212 - Block 3 - Chapter 5 - Percussion Other Drums Bass Drum –Two heads –Often one head is tighter than the other so that the frequencies do not correspond –Untuned Snare Drum –Wires across one head causes a rattle as the head moves

43 TA212 - Block 3 - Chapter 5 - Percussion Simple Gongs and Cymbals Modes of Vibration similar to a circular drum skin Low frequencies dominate first, then higher frequencies take over Untuned

44 TA212 - Block 3 - Chapter 5 - Percussion Circular Plate Vibration Modes

45 TA212 - Block 3 - Chapter 5 - Percussion Circular Plate Frequencies

46 Oriental Gong Shape forces the first two harmonics to have a frequency ratio of 2:1 Other harmonics effectively not present Tuned TA212 - Block 3 - Chapter 5 - Percussion

47 Vibrating Bars Glockenspiel, Xylophone etc

48 TA212 - Block 3 - Chapter 5 - Percussion Vibrating Bars

49 TA212 - Block 3 - Chapter 5 - Percussion Vibrating Bars The instrument is “tuned” because felt supports go here to damp all but the fundamental mode of vibration

50 TA212 - Block 3 Question: Rectangular Bar A glockenspiel bar is made out of steel whose Young’s Modulus is 201x10 9 N/m 2 and whose density is 7800 kg/m 3. The bar is 5mm thick and 111mm long. What frequency will it sound? f 1 frequency EYoung’s modulus  density tthickness Llength

51 TA212 - Block 3 - Chapter 5 - Percussion Percussion Pitch Modes of vibration do not form a harmonic series No well defined pitch, but... –Timpani Air damping within the instrument shifts the modes of vibration to produce a harmonic series –Glockenspiel Supports damp out the unwanted modes of vibration –Oriental Gong

52 Keyboard Instruments TA212: Block 3, Chapter 6

53 TA212 - Block 3 - Chapter 6 - Keyboard Instruments Keyboards Standard interface to many different ways to make a sound –clavichord –harpsichord/virginal/spinet –piano –organ –piano accordion –electronic keyboard –celesta

54 TA212 - Block 3 - Chapter 6 - Keyboard Instruments Clavichord Unfretted Clavichord - one string for each note Fretted Clavichord - several notes on each string fulcrum tangent bridge damping

55 TA212 - Block 3 - Chapter 6 - Keyboard Instruments Plucked Strings Virginal Spinet Harpsichord

56 TA212 - Block 3 - Chapter 6 - Keyboard Instruments Piano Hammers hit the string The hammer needs to: –hit the string at a controllable speed –have a clean rebound –not hit the string twice Modern mechanism invented by Cristofori in 1720

57 TA212 - Block 3 - Chapter 6 - Keyboard Instruments Piano Key Levers force effect fe force effect f e f e force

58 TA212 - Block 3 - Chapter 6 - Keyboard Instruments Cristofori Action

59 TA212 - Block 3 - Chapter 6 - Keyboard Instruments Organ

60 TA212 - Block 3 - Chapter 6 - Keyboard Instruments Organ air in valve tracker pipe windchest key roller

61 TA212 - Block 3 - Chapter 6 - Keyboard Instruments Organ Stops An Organ Stop selects a bank of pipes The length is an indication of pitch, not physical length –8ft is normal pitch (A 4 =440Hz) –4ft sounds an octave higher A stop labelled “8ft stopped” –normal pitch made with stopped pipes –NOT 8ft pipes stopped to produce the effect of 16ft pipes.

62 TA212 - Block 3 Question: Organ Stops A pipe organ is tuned in concert pitch. The key normally sounding the A above middle C (A 4 ) is pressed. What note will sound when each of the following stops are used. 8’ diapason 4’ diapason 16’ stopped Why will the tone of the 16’ stopped pipes differ from the others?

63 The Voice TA212: Block 3, Chapter 7

64 TA212 - Block 3 - Chapter 7 - The Voice Anatomy

65 TA212 - Block 3 - Chapter 7 - The Voice Voice and Clarinet sound sourcepitchtimbre clarinetreedair columnfixed voicevocal folds Variable (vocal tract)

66 TA212 - Block 3 - Chapter 7 - The Voice Graphic Equaliser The vocal tract can emphasise different frequencies Like a graphic equaliser… Different vowels are produced by emphasising different frequencies

67 TA212 - Block 3 - Chapter 7 - The Voice Vowels Shape of the vocal tract Each shape emphasises different frequencies The frequencies which are emphasised are called Formants

68 TA212 - Block 3 - Chapter 7 - The Voice Spectrogram time frequency formants

69 TA212 - Block 3 - Chapter 7 - The Voice Formant Chart first formant second formant Vowels can be characterised by the frequencies of the first two formants

70 TA212 - Block 3 - Chapter 7 - The Voice Singer’s Formant Formants pulled closer together create an increase in loudness –not more energy –more efficient use of existing energy Distorts the vowels –consonants become important for intelligibility

71 Electronic Instruments TA212: Block 3, Chapter 8

72 TA212 - Block 3 - Chapter 8 - Electronic Instruments Types of Electronic Instrument Electroacoustic –sound source is mechanical (string of electric guitar) Electromechanical –replays physical representations of sounds (Hammond organ) Electronic –sound is created from an electronic circuit (synthesiser)

73 TA212 - Block 3 - Chapter 8 - Electronic Instruments Electromagnetic Induction Given any two, the third is produced electricity + magnetism = motion (electric motor) magnetism + motion = electricity (generator) electricity magnetismmotion

74 TA212 - Block 3 - Chapter 8 - Electronic Instruments Electric Guitar Electroacoustic Electromagnetic induction –“movement + magnetism = electricity”

75 TA212 - Block 3 - Chapter 8 - Electronic Instruments Hammond Organ Electromechanical Electromagnetic induction –“movement + magnetism = electricity” –the lobes on the spinning wheel disturb the magnetic field creating a current in the wire magnet spinning wheel wire

76 TA212 - Block 3 - Chapter 8 - Electronic Instruments Moog Synthesiser Electronic No moving parts! Analogue

77 TA212 - Block 3 - Chapter 8 - Electronic Instruments BBC Radiophonic Workshop

78 TA212 The Technology of Music Contacting Me Phone Web

79 TA212 The Technology of Music Questions ? ? ? ? ? ? ?


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