ROOM ACOUSTICS

INTRODUCTION

SOUND ABSORPTION

DIRECT SOUND PATH

REFLECTED SOUND PATH

REVERBERATION

INTRODUCTION

DEFINITION:

THE BEHAVIOR OF SOUND IN ENCLOSED SPACES.HOW THE ACOUSTICAL ENVIRONMENT AFFECTS THE FUNCTIONS & ACTIVITIES IN THE SPACE.

ROOM ACOUSTICS

INTRODUCTION

SOUND ABSORPTION

DIRECT SOUND PATH

REFLECTED SOUND PATH

REVERBERATION

INTRODUCTION

SOUND DISTRIBUTION:

ROOM SHAPE

PLACEMENT OF REFLECTIVE AND ABSORPTIVE SURFACES.

ROOM ACOUSTICS

INTRODUCTION

SOUND ABSORPTION

DIRECT SOUND PATH

REFLECTED SOUND PATH

REVERBERATION

SOUND ABSORPTION

ROOM ACOUSTICS

INTRODUCTION

SOUND ABSORPTION

DIRECT SOUND PATH

REFLECTED SOUND PATH

REVERBERATION

ABSORPTION COEFFICIENT

ABSORPTION COEFFICIENT:

DESCRIBES THE FRACTION OF THE INCIDENT SOUND ENERGY THAT A MATERIAL ABSORBS. THEORETICALLY IT CAN VARY FROM 0 (NO SOUND ENERGY ABSORBED) TO 1.0 (PERFECT ABSORPTION OF ALL INCIDENT SOUND ENERGY)

ROOM ACOUSTICS

INTRODUCTION

SOUND ABSORPTION

DIRECT SOUND PATH

REFLECTED SOUND PATH

REVERBERATION

NOISE REDUCTION COEFFICIENT

ROOM ACOUSTICS

INTRODUCTION

SOUND ABSORPTION

DIRECT SOUND PATH

REFLECTED SOUND PATH

REVERBERATION

SABINES

ROOM ACOUSTICS

INTRODUCTION

SOUND ABSORPTION

DIRECT SOUND PATH

REFLECTED SOUND PATH

REVERBERATION

DIRECT SOUND

ROOM ACOUSTICS

INTRODUCTION

SOUND ABSORPTION

DIRECT SOUND PATH

REFLECTED SOUND PATH

REVERBERATION

DIRECT SOUND

IMPROVING THE DIRECT SOUND PATH:

PLACING THE AUDIENCE AS CLOSE AS POSSIBLE TO THE STAGE.

ROOM ACOUSTICS

INTRODUCTION

SOUND ABSORPTION

DIRECT SOUND PATH

REFLECTED SOUND PATH

REVERBERATION

PLACING THE AUDIENCE AS CLOSE AS POSSIBLE TO THE STAGE.

ROOM ACOUSTICS

INTRODUCTION

SOUND ABSORPTION

DIRECT SOUND PATH

REFLECTED SOUND PATH

REVERBERATION

PLACING THE AUDIENCE AS CLOSE AS POSSIBLE TO THE STAGE.

IMPROVING THE DIRECT SOUND PATH:

PLACING THE AUDIENCE AS CLOSE AS POSSIBLE TO THE STAGE THROUGH STACKED BALCONIES.

ROOM ACOUSTICS

INTRODUCTION

SOUND ABSORPTION

DIRECT SOUND PATH

REFLECTED SOUND PATH

REVERBERATION

IMPROVING THE DIRECT SOUND PATH

IMPROVING THE DIRECT SOUND PATH:

RAISING THE SOURCE IN HEIGHT.

ROOM ACOUSTICS

INTRODUCTION

SOUND ABSORPTION

DIRECT SOUND PATH

REFLECTED SOUND PATH

REVERBERATION

IMPROVING THE DIRECT SOUND PATH

IMPROVING THE DIRECT SOUND PATH:

RAISING THE SOURCE IN HEIGHT.

ROOM ACOUSTICS

INTRODUCTION

SOUND ABSORPTION

DIRECT SOUND PATH

REFLECTED SOUND PATH

REVERBERATION

IMPROVING THE DIRECT SOUND PATH

IMPROVING THE DIRECT SOUND PATH:

RAKING THE SEATING.

ROOM ACOUSTICS

INTRODUCTION

SOUND ABSORPTION

DIRECT SOUND PATH

REFLECTED SOUND PATHDESCRIPTION

RAY-DIAGRAMS

HORIZONTAL SURFACES

INCLINED SURFACES

CONVEX SURFACES

CONCAVE SURFACES

ECHOES

DIFFRACTION

REVERBERATION

REFLECTED SOUND PATH

ROOM ACOUSTICS

INTRODUCTION

SOUND ABSORPTION

DIRECT SOUND PATH

REFLECTED SOUND PATHDESCRIPTION

RAY-DIAGRAMS

HORIZONTAL SURFACES

INCLINED SURFACES

CONVEX SURFACES

CONCAVE SURFACES

ECHOES

DIFFRACTION

REVERBERATION

RAY-DIAGRAMS

RAY DIAGRAMS:

PROCEDURE FOR ANALYZING REFLECTED SOUND.

RAYS ARE DRAWN NORMAL TO THE SPHERICALLY PROPAGATING OF WAVES.

SPECULAR REFLECTION IS ASSUMED.

ROOM ACOUSTICS

INTRODUCTION

SOUND ABSORPTION

DIRECT SOUND PATH

REFLECTED SOUND PATHDESCRIPTION

RAY-DIAGRAMS

HORIZONTAL SURFACES

INCLINED SURFACES

CONVEX SURFACES

CONCAVE SURFACES

ECHOES

DIFFRACTION

REVERBERATION

RAY-DIAGRAMS

ROOM ACOUSTICS

INTRODUCTION

SOUND ABSORPTION

DIRECT SOUND PATH

REFLECTED SOUND PATHDESCRIPTION

RAY-DIAGRAMS

HORIZONTAL SURFACES

INCLINED SURFACES

CONVEX SURFACES

CONCAVE SURFACES

ECHOES

DIFFRACTION

REVERBERATION

RAY-DIAGRAMS

LIMITATIONS OF RAY DIAGRAMS:

THE SPACE IS THREE-DIMENSIONAL BUT THE DIAGRAM IS TWO-DIMENSIONAL.

COMPLICATED BY VARIOUS SPEAKING POSITIONS.NOT APPLICABLE TO LOW-FREQUENCIES (BELOW 250HZ).

ROOM ACOUSTICS

INTRODUCTION

SOUND ABSORPTION

DIRECT SOUND PATH

REFLECTED SOUND PATHDESCRIPTION

RAY-DIAGRAMS

HORIZONTAL SURFACES

INCLINED SURFACES

CONVEX SURFACES

CONCAVE SURFACES

ECHOES

DIFFRACTION

REVERBERATION

DIFFUSION OF SOUND: WHEN SOUND REFLECTS OFF A FLAT HORIZONTAL SURFACE, A DEGREE OF DIFFUSION IS PROVIDED.

ROOM ACOUSTICS

INTRODUCTION

SOUND ABSORPTION

DIRECT SOUND PATH

REFLECTED SOUND PATHDESCRIPTION

RAY-DIAGRAMS

HORIZONTAL SURFACES

INCLINED SURFACES

CONVEX SURFACES

CONCAVE SURFACES

ECHOES

DIFFRACTION

REVERBERATION

FLUTTER ECHO

FLUTTER ECHO:

REPEATED ECHOES TRAVERSING BACK AND FORTH BETWEEN TWO PARALLEL SURFACES.

REQUIRES AN IMPULSE SOURCE.

PERCEIVED AS A BUZZING OR CLICKING SOUND.

ROOM ACOUSTICS

INTRODUCTION

SOUND ABSORPTION

DIRECT SOUND PATH

REFLECTED SOUND PATHDESCRIPTION

RAY-DIAGRAMS

HORIZONTAL SURFACES

INCLINED SURFACES

CONVEX SURFACES

CONCAVE SURFACES

ECHOES

DIFFRACTION

REVERBERATION

STANDING WAVES (ROOM RESONANCE)

STANDING WAVES (ROOM RESONANCE):

SIMILAR TO FLUTTER IN PRINCIPLE BUT CAUSED BY PURE TONE SOURCES.

PERCEIVED AS VARIATIONS IN SOUND LEVEL.

ROOM ACOUSTICS

INTRODUCTION

SOUND ABSORPTION

DIRECT SOUND PATH

REFLECTED SOUND PATHDESCRIPTION

RAY-DIAGRAMS

HORIZONTAL SURFACES

INCLINED SURFACES

CONVEX SURFACES

CONCAVE SURFACES

ECHOES

DIFFRACTION

REVERBERATION

STANDING WAVES (ROOM RESONANCE)

DESCRIPTION:STANDING WAVES WILL OCCUR WHEN PARALLEL WALLS ARE SOME INTEGRAL MULTIPLE OF HALF A WAVE LENGTH APART.THEY OCCUR ONLY IN SMALL ROOMS (30’ OR LESS FOR MUSIC & 15’ OR LESS FOR SPEECH.

ROOM ACOUSTICS

INTRODUCTION

SOUND ABSORPTION

DIRECT SOUND PATH

REFLECTED SOUND PATHDESCRIPTION

RAY-DIAGRAMS

HORIZONTAL SURFACES

INCLINED SURFACES

CONVEX SURFACES

CONCAVE SURFACES

ECHOES

DIFFRACTION

REVERBERATION

FLUTTER ECHO & ROOM RESONANCE

METHODS OF CONTROL:

SOUND ABSORBING TREATMENT.

NONPARALLEL-WALL SURFACES.

SOUND-DIFFUSING WALL MODULATION.

ROOM ACOUSTICS

INTRODUCTION

SOUND ABSORPTION

DIRECT SOUND PATH

REFLECTED SOUND PATHDESCRIPTION

RAY-DIAGRAMS

HORIZONTAL SURFACES

INCLINED SURFACES

CONVEX SURFACES

CONCAVE SURFACES

ECHOES

DIFFRACTION

REVERBERATION

METHODS OF CONTROL: NONPARALLEL-WALL SURFACES & SOUND-DIFFUSING WALL MODULATION.

ROOM ACOUSTICS

INTRODUCTION

SOUND ABSORPTION

DIRECT SOUND PATH

REFLECTED SOUND PATHDESCRIPTION

RAY-DIAGRAMS

HORIZONTAL SURFACES

INCLINED SURFACES

CONVEX SURFACES

CONCAVE SURFACES

ECHOES

DIFFRACTION

REVERBERATION

INCLINED FLAT SURFACES

GREATER DIFFUSION IS PROVIDED.IF THE INCLINATION IS UP TOWARD THE AUDIENCE, SOUND IS PROJECTED DEEPER INTO THE ROOM.CAN INCREASE USEFUL CEILING REFLECTIVE SURFACE.

ROOM ACOUSTICS

INTRODUCTION

SOUND ABSORPTION

DIRECT SOUND PATH

REFLECTED SOUND PATHDESCRIPTION

RAY-DIAGRAMS

HORIZONTAL SURFACES

INCLINED SURFACES

CONVEX SURFACES

CONCAVE SURFACES

ECHOES

DIFFRACTION

REVERBERATION

SOUNDING BOARD

GREATER DIFFUSION IS PROVIDED.IF THE INCLINATION IS UP TOWARD THE AUDIENCE, SOUND IS PROJECTED DEEPER INTO THE ROOM.CAN INCREASE USEFUL CEILING REFLECTIVE SURFACE.

ROOM ACOUSTICS

INTRODUCTION

SOUND ABSORPTION

DIRECT SOUND PATH

REFLECTED SOUND PATHDESCRIPTION

RAY-DIAGRAMS

HORIZONTAL SURFACES

INCLINED SURFACES

CONVEX SURFACES

CONCAVE SURFACES

ECHOES

DIFFRACTION

REVERBERATION

SOUNDING BOARD

DESCRIPTION:

THE SOUND SOURCE SHOULD BE CLOSELY AND ABUNDANTLY SURROUNDED WITH LARGE SOUND-REFLECTING SURFACES, SUCH AS PLASTER OR CONCRETE, TO INSURE ADEQUATE LOUDNESS IN REMOTE AREAS.

ROOM ACOUSTICS

INTRODUCTION

SOUND ABSORPTION

DIRECT SOUND PATH

REFLECTED SOUND PATHDESCRIPTION

RAY-DIAGRAMS

HORIZONTAL SURFACES

INCLINED SURFACES

CONVEX SURFACES

CONCAVE SURFACES

ECHOES

DIFFRACTION

REVERBERATION

PROVIDES THE GREATEST DIFFUSION.IN A DIFFUSE SOUND FIELD THE SOUND LEVEL REMAINS RELATIVELY CONSTANT THROUGHOUT THE SPACE

WHICH IS EXTREMELY DESIRABLE FOR MUSIC.

ROOM ACOUSTICS

INTRODUCTION

SOUND ABSORPTION

DIRECT SOUND PATH

REFLECTED SOUND PATHDESCRIPTION

RAY-DIAGRAMS

HORIZONTAL SURFACES

INCLINED SURFACES

CONVEX SURFACES

CONCAVE SURFACES

ECHOES

DIFFRACTION

REVERBERATION

CONVEX SURFACES

ROOM ACOUSTICS

INTRODUCTION

SOUND ABSORPTION

DIRECT SOUND PATH

REFLECTED SOUND PATHDESCRIPTION

RAY-DIAGRAMS

HORIZONTAL SURFACES

INCLINED SURFACES

CONVEX SURFACES

CONCAVE SURFACES

ECHOES

DIFFRACTION

REVERBERATION

FOCUSING

CONCAVE SURFACES:

REFLECTED SOUND IS CONCENTRATED INTO CERTAIN AREAS.

CREATES HOT AND DEAD SPOTS ACOUSTICALLY.

ROOM ACOUSTICS

INTRODUCTION

SOUND ABSORPTION

DIRECT SOUND PATH

REFLECTED SOUND PATHDESCRIPTION

RAY-DIAGRAMS

HORIZONTAL SURFACES

INCLINED SURFACES

CONVEX SURFACES

CONCAVE SURFACES

ECHOES

DIFFRACTION

REVERBERATION

FOCUSING

ROOM ACOUSTICS

INTRODUCTION

SOUND ABSORPTION

DIRECT SOUND PATH

REFLECTED SOUND PATHDESCRIPTION

RAY-DIAGRAMS

HORIZONTAL SURFACES

INCLINED SURFACES

CONVEX SURFACES

CONCAVE SURFACES

ECHOES

DIFFRACTION

REVERBERATION

CREEP

REFLECTION OF SOUND ALONG A CURVED SURFACE FROM A SOURCE NEAR THE SURFACE.

ALTHOUGH THE SOUND CAN BE HEARD AT POINTS ALONG THE SURFACE, IT IS INAUDIBLE AWAY FROM THE SURFACE..

ROOM ACOUSTICS

INTRODUCTION

SOUND ABSORPTION

DIRECT SOUND PATH

REFLECTED SOUND PATHDESCRIPTION

RAY-DIAGRAMS

HORIZONTAL SURFACES

INCLINED SURFACES

CONVEX SURFACES

CONCAVE SURFACES

ECHOES

DIFFRACTION

REVERBERATION

CREEP

METHODS OF CONTROL:

SURFACE UNDULATIONS.

SOUND ABSORBING TREATMENT.

ROOM ACOUSTICS

INTRODUCTION

SOUND ABSORPTION

DIRECT SOUND PATH

REFLECTED SOUND PATHDESCRIPTION

RAY-DIAGRAMS

HORIZONTAL SURFACES

INCLINED SURFACES

CONVEX SURFACES

CONCAVE SURFACES

ECHOES

DIFFRACTION

REVERBERATION

EERO SAARINEN, MIT CHAPEL

ROOM ACOUSTICS

INTRODUCTION

SOUND ABSORPTION

DIRECT SOUND PATH

REFLECTED SOUND PATHDESCRIPTION

RAY-DIAGRAMS

HORIZONTAL SURFACES

INCLINED SURFACES

CONVEX SURFACES

CONCAVE SURFACES

ECHOES

DIFFRACTION

REVERBERATION

ECHOES

ECHO:

THE DISTINCT REPETITION OF THE ORIGINAL SOUND SUCH THAT IT IS SUFFICIENTLY LOUD TO BE CLEARLY HEARD ABOVE GENERAL REVEBERATION.

ROOM ACOUSTICS

INTRODUCTION

SOUND ABSORPTION

DIRECT SOUND PATH

REFLECTED SOUND PATHDESCRIPTION

RAY-DIAGRAMS

HORIZONTAL SURFACES

INCLINED SURFACES

CONVEX SURFACES

CONCAVE SURFACES

ECHOES

DIFFRACTION

REVERBERATION

ECHOES

DESCRIPTION:

ECHOES OCCUR WHEN THE REFLECTED SOUND PATH EXCEEDS THE DIRECT SOUND PATH BY MORE THAN 60 FEET.

ROOM ACOUSTICS

INTRODUCTION

SOUND ABSORPTION

DIRECT SOUND PATH

REFLECTED SOUND PATHDESCRIPTION

RAY-DIAGRAMS

HORIZONTAL SURFACES

INCLINED SURFACES

CONVEX SURFACES

CONCAVE SURFACES

ECHOES

DIFFRACTION

REVERBERATION

ECHOES

CONTROL: USE OF SOUND ABSORBING MATERIAL OR INCLINING CEILING SURFACE.

ROOM ACOUSTICS

INTRODUCTION

SOUND ABSORPTION

DIRECT SOUND PATH

REFLECTED SOUND PATHDESCRIPTION

RAY-DIAGRAMS

HORIZONTAL SURFACES

INCLINED SURFACES

CONVEX SURFACES

CONCAVE SURFACES

ECHOES

DIFFRACTION

REVERBERATION

DIFFRACTION

THE BENDING OR FLOWING OF A SOUND WAVE AROUND AN OBJECT OR THROUGH AN OPENING.

IMPINGING SOUND WAVES WILL READILY DIFFRACT AROUND PANELS THAT ARE SMALLER THAN THEIR WAVELENGTH.

ROOM ACOUSTICS

INTRODUCTION

SOUND ABSORPTION

DIRECT SOUND PATH

REFLECTED SOUND PATH

REVERBERATIONDESCRIPTION

PATTERNS OF REVERBERANT DECAY

REVERBERATION TIME

REVERBERATION

REVERBERATION:

THE PERSISTENCE OF SOUND AT MID-FREQUENCIES.

DETERMINED BY ROOM VOLUME AND TOTAL ABSORPTION AT THAT FREQUENCY.

ROOM ACOUSTICS

INTRODUCTION

SOUND ABSORPTION

DIRECT SOUND PATH

REFLECTED SOUND PATH

REVERBERATIONDESCRIPTION

PATTERNS OF REVERBERANT DECAY

REVERBERATION TIME

SOUND IN A LARGE ROOM

ROOM ACOUSTICS

INTRODUCTION

SOUND ABSORPTION

DIRECT SOUND PATH

REFLECTED SOUND PATH

REVERBERATIONDESCRIPTION

PATTERNS OF REVERBERANT DECAY

REVERBERATION TIME

SOUND IN A SMALL ROOM

ROOM ACOUSTICS

INTRODUCTION

SOUND ABSORPTION

DIRECT SOUND PATH

REFLECTED SOUND PATH

REVERBERATIONDESCRIPTION

PATTERNS OF REVERBERANT DECAY

REVERBERATION TIME

REVERBERATION TIME

REVERBERATION TIME:

THE TIME REQUIRED FOR SOUND TO DECAY 60 DECIBELS AFTER THE SOURCE HAS STOPPED.