�ݺ�ߣ

Copyright © 2017 by Milap Bhanderi
Subject: Physics
Institute: Silver Oak College of Engineering and Technology.
ACOUSTICSby

ACOUSTICS
•  “A SCIENCE THAT DEALS WITH THE PRODUCTION,
CONTROL, TRANSMISSION, RECEPTION, AND
EFFECTS OF SOUND.”
•  ACOUSTICS IS ADDRESSED IN THE TEXT “INTERIOR
CONSTRUCTION & DETAILING”

•  SOUND IS REFLECTED, TRANSMITTED, OR
ABSORBED BY THE MATERIALS IT ENCOUNTERS.
•  SOFT SURFACES, SUCH AS TEXTILES AND TEND TO
ABSORB SOUND WAVES, PREVENTING THEM
FROM FURTHER MOTION.
•  DENSE, MASSIVE, MATERIALS, SUCH AS
CONCRETE OR BRICK, TEND TO TRANSMIT SOUND
WAVES THROUGH THE MATERIAL.

•  HIGH FREQUENCY SOUND WAVES (THINK OF A HIGH
WHISTLE) ARE NOT CAPABLE OF BEING TRANSMITTED
THROUGH MASSIVE, HEAVY, MATERIAL.
•  LOW FREQUENCY SOUND WAVES (BASS) ARE
TRANSMITTED THROUGH MASSIVE MATERIALS.

THE HUMAN EAR IS CAPABLE OF HEARING
SOUNDS WITHIN
A LIMITED RANGE.

ANIMALS HAVE VARIED HEARING
RANGES

HEARING RANGE OF SOME ANIMALS

•  MANY ANIMALS HEAR A MUCH WIDER RANGE OF
FREQUENCIES THAN HUMAN BEINGS DO.
•  FOR EXAMPLE, DOG WHISTLES VIBRATE AT A HIGHER
FREQUENCY THAN THE HUMAN EAR CAN DETECT,
WHILE EVIDENCE SUGGESTS THAT DOLPHINS AND
WHALES COMMUNICATE AT FREQUENCIES BEYOND
HUMAN HEARING (ULTRASOUND).
•  FREQUENCY IS MEASURED IN HERTZ, OR THE NUMBER
OF SOUND WAVES A VIBRATING OBJECT GIVES OFF
PER SECOND. THE MORE THE OBJECT VIBRATES, THE
HIGHER THE FREQUENCY AND THE HIGHER THE PITCH
OF THE RESULTING SOUND.

DECIBEL LEVELS
•  0 THE SOFTEST SOUND A PERSON CAN HEAR WITH
NORMAL HEARING
•  10 NORMAL BREATHING
•  20 WHISPERING AT 5 FEET
•  30 SOFT WHISPER
•  50 RAINFALL
•  60 NORMAL CONVERSATION
•  110 SHOUTING IN EAR
•  120 THUNDER

DECIBEL LEVELS
•  THE HUMAN EAR'S RESPONSE TO SOUND LEVEL IS ROUGHLY
LOGARITHMIC (BASED ON POWERS OF 10), AND THE DB SCALE
REFLECTS THAT FACT.
•  AN INCREASE OF 3DB DOUBLES THE SOUND INTENSITY BUT A
10DB INCREASE IS REQUIRED BEFORE A SOUND IS PERCEIVED TO
BE TWICE AS LOUD.
•  THEREFORE A SMALL INCREASE IN DECIBELS
REPRESENTS A LARGE INCREASE IN INTENSITY.
•  FOR EXAMPLE - 10DB IS 10 TIMES MORE INTENSE
THAN 1DB, WHILE 20DB IS 100 TIMES MORE INTENSE
THAN 1DB.
•  THE SOUND INTENSITY MULTIPLIES BY 10 WITH EVERY
10DB INCREASE. Copyright © 2017 by Milap Bhanderi

AN ANECHOIC CHAMBER IS A SPACE IN WHICH
THERE ARE NO ECHOES OR REVERBERATIONS.
THE SURFACES ABSORB ALL SOUND, AND REFLECT NONE.

ACOUSTICS: SOUND
•  SOUND IS A MECHANICAL WAVE AND THEREFORE REQUIRES A
MEDIUM IN WHICH IT CAN TRAVEL.
•  ACOUSTICS IS CLASSICALLY DIVIDED INTO SOUND AND
VIBRATION.
•  SOUND REFERS TO WAVEFORMS TRAVELING THROUGH A FLUID
MEDIUM SUCH AS AIR
•  VIBRATION DESCRIBES ENERGY TRANSMITTED THROUGH DENSER
MATERIALS SUCH AS WOOD, STEEL, STONE, DIRT, DRYWALL OR
ANYTHING BESIDES A FLUID.

THE SPEED OF SOUND VERSUS
THE SPEED OF LIGHT
•  SOUND TRAVELS AT 1130 FEET PER SECOND AT
NORMAL ROOM TEMPERATURE.
•  LIGHT TRAVELS AT 299,792,458 METERS PER SECOND,
WHICH IS ROUGHLY 974,325,489 FEET PER SECOND
(974 MILLION FEET PER SECOND!!)

SOUND WAVES:
AMPLITUDE & FREQUENCY (CYCLES)

RADIO SIGNALS: AM & FM

• ‘AM’ MEANS: AMPLITUDE MODULATION: THE HEIGHT
OF EACH WAVE CHANGES
• ‘FM’ MEANS: FREQUENCY MODULATION: THE LENGTH
OF EACH WAVE CHANGES
• FM SIGNALS HAVE A GREAT ADVANTAGE OVER AM
SIGNALS.
• BOTH SIGNALS ARE SUSCEPTIBLE TO SLIGHT CHANGES
IN AMPLITUDE.

BONDED ACOUSTICAL COTTON; RECYCLED COTTON, CLASS A
NON FLAMMABLE
MELAMINE FOAM ACOUSTICAL PANELS: FIBER FREE, CLASS A
FIRE RETARDENT

ADVANCED STUDY OF
ACOUSTICS
•  ACOUSTICS IS THE SUBJECT OF FORMAL,
ADVANCED STUDY, INCLUDING THE FIELDS OF
ENGINEERING, ARCHITECTURE, AND
PSYCHOLOGY.
•  FOR EXAMPLE, THE SCHOOL OF
ARCHITECTURE AT RENSSELAER POLYTECHNIC
INSTITUTE OFFERS A FORMAL PROGRAM FOR
A MASTERS OF SCIENCE DEGREE IN BUILDING
SCIENCE (CONCENTRATION IN
ARCHITECTURAL ACOUSTICS)

•  RESEARCHERS IN THE ACOUSTICS PROGRAM IN
THE SCHOOL OF ARCHITECTURE ARE
INVESTIGATING HOW THE DESIGN OF A
CLASSROOM CAN AFFECT HOW EASILY STUDENTS
HEAR.
•  THE RESEARCHERS BELIEVE THAT IF MORE
ATTENTION IS PAID TO CLASSROOM ACOUSTICS
WHEN DESIGNING THE SPACE, STUDENTS WILL
HAVE AN EASIER TIME LEARNING AND
UNDERSTANDING WHAT'S GOING ON.

MUSIC AND DRAMA THEATER ACOUSTICS
•  THE ACOUSTICAL CHARACTERISTICS OF A
VENUE FOR THE LIVE PERFORMANCE OF
MUSIC OR DRAMA ARE AN IMPORTANT
PART OF THE AUDIENCE EXPERIENCE.
•  FOR MUSIC PERFORMANCE, THE ROOM
BECOMES PART OF THE INSTRUMENT,
HELPING DEFINE THE CHARACTER OF THE
MUSICAL SOUND THAT THE AUDIENCE
HEARS.

REVERBERATION TIME
•  REVERBERATION TIME REFERS TO THE AMOUNT OF TIME REQUIRED
FOR THE SOUND FIELD IN A SPACE TO DECAY 60DB, OR TO ONE
MILLIONTH OF THE ORIGINAL POWER.
•  IN SIMPLE TERMS THIS REFERS TO THE AMOUNT OF TIME IT TAKES
FOR SOUND ENERGY TO BOUNCE AROUND A ROOM BEFORE
BEING ABSORBED BY THE MATERIALS AND AIR

•  REVERBERATION TIME IS IMPORTANT BECAUSE
IT CAN AFFECT HOW WELL YOU UNDERSTAND
SPEECH, AND IT CAN CHANGE THE WAY
MUSIC SOUNDS.
•  THE EFFECT ON SPEECH INTELLIGIBILITY IS
NOTICEABLE IN A GYMNASIUM OR ARENA,
WHERE YOU OFTEN CAN'T UNDERSTAND
SOMEONE WHO IS ONLY 10 OR 15 FEET AWAY
FROM YOU

'STRADIA': A SOUND SIMULATION
PROGRAM

CONCERT HALLS DEMAND VERY
CAREFUL
ACOUSTICAL ANALYSIS

THE SYDNEY OPERA HOUSE CONCERT HALL
BUILDING DESIGNED BY JORN UTZON

�ݺ�ߣ

ACOUSTIC - Physics

More Related Content

ACOUSTIC - Physics