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GEOMETRICAL DESIGN STUDIES

GEOMETRICAL DESIGN STUDIES. ACOUSTICS OF CONCERT HALLS AND ROOMS. Handbook of Acoustics, Chapter 9 Long, Architectural Acoustics, Chapter 19. THE LISTENING ENVIRONMENT. • STRONG LATERAL REFLECTIONS SO AUDIENCE FEELS ENVELOPED • A STRONG REVERBERANT FIELD

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GEOMETRICAL DESIGN STUDIES

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  1. GEOMETRICAL DESIGN STUDIES ACOUSTICS OF CONCERT HALLS AND ROOMS Handbook of Acoustics, Chapter 9 Long, Architectural Acoustics, Chapter 19

  2. THE LISTENING ENVIRONMENT • STRONG LATERAL REFLECTIONS SO AUDIENCE FEELS ENVELOPED • A STRONG REVERBERANT FIELD • CLARITY AND DEFINITION FOR RAPID MUSICAL PASSAGES • ADEQUATE LOUDNESS THROUGHOUT THE HALL • ROOM MUST NOT COLOR THE NATURAL INSTRUMENT SPECTRA • LOW BACKGROUND NOISE (NC 20 OR LESS) •SMOOTH DECAY WITHOUT ECHOES • PERFORMERS SHOULD BE ABLE TO HEAR EACH OTHER (ENSEMBLE)

  3. HALL SIZE SEATING CAPACITY PAYS THE RENT HOWEVER THE “BEST LIKED” CONCERT HALLS HAVE CAPACITIES OF ABOUT 1800-1900 SEATS “LEAST LIKED” HALLS AVERAGED 2800 SEATS

  4. BASIC ROOM SHAPES FAN-SHAPED GREEK/ROMAN THEATER CIRCUS OR ARENA

  5. NORMAL SURROUND SIMPLE PLAN FORMS FOR CONCERT HALLS IN NORMAL AND SURROUND CONFIGURATIONS

  6. DIRECTIONS OF SIDE-WALL REFLECTIONS DEPENDING ON ROOM SHAPE RECTANGULAR FAN-SHAPE

  7. GRAZING INCIDENCE (LESS THAN 5O) FOR REFLECTION AT A HARD SURFACE, REFLECTED WAVE IS IN PHASE WITH INCIDENT WAVE AND PRODUCES AN INCREASE (OR DECREASE) IN SOUND LEVEL 10-20 dB IN FOR REFLECTION AT A SOFT SURFACE (SUCH AS THE HEADS OF THE AUDIENCE) REFLECTED WAVE IS 180O OUT OF PHASE WITH INCIDENT WAVE AND WAVE INTERFERENCE CAN AMOUNT TO 10--20 dB IN THE 100--800 Hz RANGE (GADE, 2007)

  8. SEATING ARRANGEMENT GRAZING INCIDENCE ATTENUATES NOT ONLY THE DIRECT SOUND BUT ALSO THE FIRST-ORDER REFLECTIONS FROM THE SIDE WALLS. THIS RESULTS IN WEAKER EARLY REFLECTIONS AND REDUCED CLARITY, INTIMACYand WARMTHIN THE ORCHESTRA SEATS (“STALLS”) NORMALLY A CLEARANCE OF 8 cm WILL SUFFICE TO AVOID GRAZING-INCIDENCE ATTENUATION, BUT SIGHT LINES WILL STILL BE UNSATISFACTORY (UNLESS SEATS ARE STAGGERED), INCREASING THE CLEARANCE TO 12 cm WILL MAKE BOTH ACOUSTIC AND VISUAL CONDITIONS SATISFACTORY, BUT THIS IMPLIES A STEEPER FLOOR SLOPE.

  9. CALCULATION OF A FLOOR SLOPE WITH CONSTANT CLEARANCE A CURVED FLOOR SLOPE WITH CONSTANT CLEARANCE MAY PREVENT EXCESS CLEARANCE IN SEATS CLOSE TO THE SOURCE

  10. SECTION OF A HALL WITH A REAR BALCONY AND CONSTANT CLEARANCE. THE RESULT IS AN INCREASED SLOPE FOR THE ELEVATED BALCONY FOR SAFETY THE SLOPE SHOULD NOT EXCEED ABOUT 35O

  11. IMPORTANT PARAMETERS FOR MAINTAINING PROPER SOUND IN SEATS OVERHUNG BY BALCONIES FOR THEATERS, H>2D FOR CONCERT HALLS H>D (GADE, 2007)

  12. UNDER BALCONY EARLY DECAY TIME EDT (Barron, 1993)

  13. VOLUME AND CEILING HEIGHT VOLUME INFLUENCES BOTH REVERBERANCE AND LOUDNESS. FOR HALLS OF HIGH CAPACITY, A LOW VOLUME PER SEAT HELPS PRESERVE ACOUSTICAL ENERGY. THOSE WHO PREFER THE MODEL OF BOSTON SYMPHONY HALL PREFER AROUND 9 m3 (320 cu ft) PER SEAT. HALLS SUCH AS McDERMOTT AND BIRMINGHAM (WITH OPENABLE REVERBERATION CHAMBERS) ARE AT OR ABOVE 11 m3 (400 cu ft). THESE HALLS INCLUDE A LARGE MOVEABLE REFLECTOR ABOVE THE ORCHESTRA WHICH OFFSETS SOME OF THE EFFECTS OF A HIGH VOLUME (Long, 2006)

  14. VOLUME PER SEAT FOR SEVERAL HALLS (Long)

  15. ECHO ELIPSES DRAWN WITH SOURCE AND RECEIVER POINTS AT THE FOCI, AND THE SUM OF DISTANCES FROM THE FOCI EQUAL DISTANCE BETWEEN FOCI PLUS 17 m. IF A SURFACE OUTSIDE AN ELLIPSE REFLECTS SOUND TO A LISTENER, IT SHOULD BE MADE ABSORBING (Gade, 2007)

  16. RESHAPING OF CEILING PROFILE TO AVOID FOCUSING AND PROVIDE MORE EVEN SOUND DISTRIBUTION

  17. DIFFUSION BY GEOMETRIC SHAPES:TRIANGULAR RECTANGULAR PROTRUSIONS • SEMI-CYLINDRICAL • SURFACE

  18. CROSS SECTION OF A PHASE GRATING (QUADRATIC RESIDUE) SOUND DIFFUSER, AS SUGGESTED BY SCHROEDER (1975) MAXIMUM DEPTH OF THE WELLS DETERMINES THE LOW-FREQUENCY LIMIT OF THE DIFFUSER. WELL DEPTH SHOULD BE 12 TIMES WAVELENGTH AT THE LOWEST FREQUENCY. THE HIGHEST FREQUENCY IS DETERMINED BY WELL WIDTH, WHICH IS A HALF WAVELENGTH AT THE HIGHEST FREQUENCY.

  19. SYMPHONYHALLBOSTON V =18,750 m3 39 m x23.6 m x18.6 m 2625 seats Furthest seat: 40.5 m T60 = 1.85 s V/N = 7.14 m3

  20. NEUES GEWANDHAUS LEIPZIG

  21. CONCERTGEBAUW AMSTERDAM

  22. BERLIN PHILHARMONIC HALL

  23. CHRISTCHURCH TOWN HALL, NEW ZEALAND BUILT 19722662 seats, V = 20,000m3, T = 2.4s

  24. SEGERSTROM HALL, ORANGE COUNTYSeats 2900Acoustic Design, Marshall, Hyde, Paoletti

  25. STANFORD MEMORIAL CHURCH

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