Transcript harps - CCRMA

MUSIC 318
PLUCKED STRING INSTRUMENTS
HARPS
HISTORY
THE EARLIEST HARPS APPEARED IN MESOPOTAMIA
IN THE THIRD MILLENIUM BCE. THEY WERE OF THE
ARCHED VARIETY, HAVING AN OPEN L-SHAPE FRAME
WITH THE STRINGS JOINING THE TWO PARTS.
IN EGYPT, SOME OF THE EARLIEST IMAGES OF BOW
HARPS ARE FROM THE PHARAOH’S TOMBS DATING
SOME 5000 YEARS AGO. THESE HIEROGLYPHS SHOW
THAT THERE WERE MANY HARPS IN ANCIENT EGYPT.
THE EGYPTIAN PARAOH RAMSES III (1198-1166 BC) HAD
MANY BOW HARPS PAINTED IN HIS TOMB. IN THE NEW
KINGDOM, HARPS MEASURED UP TO 2 m IN HEIGHT
WITH 19 STRINGS AND WERE PLAYED SEATED OR STANDING UP
EARLY HARPS
The word "harpa" or "harp" comes from Anglo-Saxon, Old German, and Old Norse
words meaning "to pluck". By the 13th century the term was being applied
specifically to the triangular harp as opposed to the lyre harp. The earliest Gaelic
term for a wire-strung instrument was "cruit" was applied specifically to the harp by
1200. A later word used in Scotland and Ireland for the "Celtic" harp was clarsach or
cláirseach. Scottish records of the 15th and 16th centuries show that both the terms
"harp" and "clarsach" were in use at the same time, and seem to indicate that there
was a distinction between the gut-strung European-style harps and wire-strung
Gaelic clarsachs.
MODERN CONCERT HARP
THE MODERN CONCERT HARP HAS 46 or 47 STRINGS RUNNING from C1 or D1 to G7.
THE STRINGS RUN FROM THE CENTER OF THE SOUNDBOARD TO THE LEFT SIDE OF THE
NECK. AT THE TOP THEY ARE WRAPPED AROUND A TUNING PEG, USED FOR TUNING,
AND A BRIDGE PIN.
BENEATH THE BRIDGE PIN ARE THE TUNING DISCS WHICH RAISE THE PITCH ONE OR
TWO SEMITONES. THE STRINGS ARE TUNED A SEMITONE FLAT; THE FIRST DISC RAISES
THE STRING TO NATURAL; THE SECOND TO SHARP. THE SHARPING MECHANISMS ARE
CONTROLLED FROM 7 PEDALS. THE MECHANISM IS QUITE COMPLEX AND RUNS UP THE
FOREPILLAR OR POST INTO THE NECK.
CONCERT HARP
DIATONIC vs CHROMATIC STRINGING
CHROMATIC MUSIC HAS ALWAYS BEEN A CHALLENGE FOR HARP MAKERS AND
PLAYERS. THE STRINGS HAVE TO BE A FINGER-WIDTH APART AND REACHABLE
WITHIN AN ARM LENGTH. MODERN CONCERT HARPS HAVE STRINGS ARRANGED
DIATONICALLY WITH PROVISION FOR SHARPING OR FLATTING NOTES WHEN
NECESSARY.
BUILDING A HARP
DESIGNING AND BUILDING A HARP PRESENTS SEVERAL TECHNICAL CHALLENGES.
A LARGE NUMBER OF STRINGS ARE NEEDED TO OBTAIN A USEABLE PITCH RANGE, AND
THIS INEVITABLY PUTS THE SOUNDBOARD UNDER GREAT STRESS.
SECONDLY THE HARP TENDS TO BE A QUIET INSTRUMENT AND NEEDS A VERY THIN
SOUNDBOARD , WHICH PRESENTS PROBLEMS IN ANCHORING THE STRINGS.
A MODERN CONCERT HARP IS MADE STRONG ENOUGH TO WITHSTAND A TOTAL
STRING TENSION OF ABOUT 12-20 kN. THE SOUNDBOARD IS APPROXIMATELY
TRAPEZOIDAL IN SHAPE, AROUND 1.4 m IN LENGTH, 0.5 m AT THE BASE END TO 2 mm
AT THE TREBLE END. IT IS MADE OF STRIPS OF SPRUCE 7 OR 8 cm WIDE BONDED
TOGETHER, GRAIN RUNNING TRANSVERSELY AND COVERED IN A THIN VENEER WITH
LONGITUDINAL GRAIN.
THE STRINGS ARE CONNECTED THROUGH TWO STRONG RIBS OR BARS OF
HARDWOOD, ONE ON EACH SIDE OF THE SOUNDBOARD, MOUNTED CENTRALLY, THE
COVER BAR VISIBLE ON THE FRONT AND THE HEAVIER REINFORCING BAR INSIDE. IN
ADDITION, HARMONIC BARS ARE MOUNTED APPROXIMATELY LONGITUDINALLY ON
THE BACK OF THE SOUNDBOARD.
VIBRATIONAL MODES OF SOUNDBOARD
TUNING
MECHANISM
STRING LENGTHS AND MATERIALS
STRING TENSION
SALVI AURORA 47-STRING CONCERT HARP
STRESS
SOUNDBOX
THE EARLIEST HARPS WERE CARVED FROM SOLID WOOD. IN THE 17TH CENTURY,
HARPS WERE CONSTRUCTED OF THINNER WOOD PARTS GLUED TOGETHER AND
BRACED. THE MODERN SOUNBOARD CONSISTS OF A DOZEN OR MORE PIECES, GLUED
EDGE TO EDGE WITH A THIN VENEER OF SPRUCE BONDED ON TOP OF THE
SOUNDBOARD.
THE HELMHOLTZ RESONANCE OF A TYPICAL SOUNDBOX IS FOUND TO BE ABOUT 190
Hz.
MODE FREQUENCIES, DAMPING
COEFFICIENTS, AND MODE SHAPES
FOR A CAMAC ATLANTIDE HARP
SOUND SPECTRA
SOUND SPECTRA FOR THE F3 AND F4 STRINGS OF A SALVI AURORA HARP
PLUCKED AT THE CENTER
SOUND RADIATION
ENVELOPE OF SOUND RADIATION FOR THE F4 STRING OF A SALVI AURORA HARP
PLUCKED AT THE CENTER. 14 Hz BEATING BETWEEN THE STRING (349 Hz) AND A
NEARBY SOUNDBOARD RESONANCE AT 335 Hz CAN BE SEEN
ACOUSTIC INTENSITY
• Sound intensity is the flow of acoustic power through a surface
• A sound intensity probe has two accurately-spaced microphones to
measure pressure and pressure gradient
• Active intensity denotes energy flow to the far field
• Reactive intensity denotes energy stored in the near field
SOUND RADIATION FIELD FROM A HARP
AT LOW FREQUENCY RADIATION FROM A CAMACS CONCERT HARP WAS FOUND TO BE
MOSTLY FROM THE BOTTOM PART OF THE SOUNDBOARD AND THE FIRST TWO SOUND
HOLES. IN THE FREQUENCY RANGE 100-220 Hz THE SOUND INTENSITY FIELD CAN BE
APPROXIMATED BY A SUPERPOSTION OF TWO POINT SOURCES .
FROM 220-400 Hz RADIATION FROM THE TOP SURFACE OF THE SOUNDBOARD EXCEEDS
THE RADIATION FROM THE SOUND HOLES, BUT FROM 400-470 Hz THE SOUNDHOLE
RADIATION AGAIN PREDOMINATES. THE SAME IS TRUE FROM 490-550 Hz.
RADIATION FROM THE SOUNDBOARD PREDOMINATES ABOVE 550 Hz. (Gautier and
Dauchez, 2004).
SOUND RADIATION FROM A HARP
SOUND POWER RADIATED BY THE SOUNDBOARD SURFACE (THIN LINE) AND BY THE
SOUNDBOX HOLES (THICK LINE). IN THE REGIONS A,C, and E MORE POWER IS
RADIATED THROUGH THE SOUND HOLES. IN B,D, and F, THE OPPOSITE IS TRUE (from
Gautier and Dauchez, 2004).
SOUND RADIATION FROM SOUNDBOARD SURFACE
SOUND RADIATION AT LOW FREQUENCY FROM THE SOUNDBOARD SURFACE (THIN
LINE) AND THE SOUND HOLES (THICK LINE) (Gautier and Dauchez, 2004).
THOMAS ROYSTON AND HIS COLLEAGUES (CHICAGO) HAVE DEVELOPED
COMPOSITE MATERIALS FOR HARPS.
HARP BUILDER THOM (AUSTRALIA) BUILDS
HARPS WITH ALUMINUM FRAMES AND
ROSEWOOD SOUNDBOARDS
ADARYN
METATRON
BURMESE HARP
THE BURMESE ARCHED HARP MAY HAVE COME FROM INDIA.
THIRTEEN TO SIXTEEN SILK OR NYLON STRINGS RUN FROM A LONGITUDINAL CENTER RIB
TO THE GRACEFULLY CURVED NECK. THE STRINGS ARE ATTACHED TO THE NECK BY CORDS
THAT END IN DECORATIVE TASSELS. THE WRAPPED CORDS ARE TIGHTENED OR LOOSENED
TO TUNE THE HARP.
THEY ARE GENERALLY TUNED TO
SCALES THAT RESEMBLE THE WESTERN
DIATONIC SCALE BUT WITH THE THIRD
AND SEVENTH NOTES LOWERED
ABOUT A AQUARTER TONE.
PRIOR TO THE NINETEENTH CENTURY,
BURMESE HARPS WERE USED ONLY
FOR CHAMBER MUSIC IN THE ROYAL
COURT, WHERE IT WAS THE MOST
PRIZED OF THE COURT INSTRUMENTS.
IT WAS PLAYED AS A SOLO
INSTRUMENT OR TO ACCOMPANY
SINGERS
MAGNITUDES (UPPER) AND PHASE (LOWER) OF ACOUSTIC VELICITIES IN THE SOUND HOLES
(LEFTHAND SCALE) AND SOUNDBOARD VELODITY (RIGHTHAND SCALE) FOR A CAMAC
ATLANTIDE CONCERT HARP.