AcousticsHistorical OverviewAcoustical DesignAcoustics Fundamentals

Historic OverviewGreek TheatreOpen airDirect sound pathNo sound reinforcementMinimal reverberationS: p. 785, F.18.17a

Historic Overview1st Century ADVitruvius: 10 Books of Architecture

Sound reinforcementReverberation

S: p. 785, F.18.17b

Historic OverviewLate 1700s-early 1800s

Acoustics developed as part of physics and applied mathematicsBroad outlines not specific details

1800s

1856: Prof. Joseph Henry Treatise on Acoustics Applied to Public Buildings

1877: Lord Rayleigh The Theory of Sound

1895: Wallace Clement Sabine Fogg Art Museum, 1895-1905Historic Overview

Historic OverviewBuildings

1870: Der Grosse Saal der Gesellschaft der Musikfreunde, Vienna1879: Central Music Hall, Chicago1887: Chicago Auditorium, Chicago1888: Concertgebouw, Amsterdam1900: Boston Symphony Hall, Boston

1900-1948: None of note

1948: Royal Festival Hall, London1961: Lincoln Center, New York

By the 1920sPrecise measurements became possibleIndividual design and fabrication

1920s+Radio, television, amplified sound/music, motion pictures fostered greater demand for analysis/design

Historic Overview

Today

Research to improve conditions forIndustrial noiseHearing risksConstruction noisePublic health

Historic Overview

Architects Role

Source PathReceiver

slightmajor design primarily interestinfluence

Acoustical DesignProper acoustical planning eliminates many acoustical problems before they are built

Lee Irvine

Acoustical Design RelationshipsSiteLocationOrientationPlanningInternal Layout

SiteMatch site to applicationMatch application to site

SiteFactory:Close to RR/HwySeismic

SiteRest Home:Traffic NoiseOutdoor UseContact/Isolation

SiteConcert Hall:Use building as isolatorDistance from noise

LocationTake advantage of distance/barriersDistance

LocationTake advantage of distance/barriersNatural or Man-made Berm

LocationTake advantage of distance/barriersAcoustical Barriers

LocationTake advantage of distance/barriersBuilding

OrientationOrient Building for Acoustical AdvantagePlaygroundSchool

OrientationOrient Building for Acoustical AdvantageParking LotFactoryOfficeNote: Sound is 3-dimensional, check overhead for flight paths

PlanningConsider Acoustical Sensitivity of ActivitiesNoisy QuietBarrier

PlanningConsider Acoustical Sensitivity of ActivitiesCritical

Non-Critical

Noise

Internal LayoutEach room has needs that can be met by room layoutI: p.116 F.5-12

Basic Acoustic GoalsProvide adequate isolationProvide appropriate acoustic environmentProvide appropriate internal functionIntegrate 1-3 amongst themselves and into comprehensive architectural design

Mechanical vibration, physical wave or series of pressure vibrations in an elastic medium

Described in Hertz (cycles per second)

Range of hearing: 20-20,000 hz

Sound

Any unwanted sound

Noise

Sound travels at different speeds through various media.MediaSpeed (C)Air:1,130 fpsWater: 4,625 fpsWood: 10,825 fpsSteel: 16,000 fps

Sound Propagation

Sound Power (P)Sound Intensity (I)

Sound Magnitude

Sound PowerEnergy radiating from a point source in space.

Expressed as watts

S: p. 750, F.17.9

Sound IntensitySound power distributed over an area

I=P/A

I: sound (power) intensity, W/cm2P: acoustic power, wattsA: area (cm2)

Intensity LevelLevel of sound relative to a base reference

S: p. 750, T.17.210 million million: one

Intensity Level Scale ChangeChanges are measured in decibels

scale changesubjective loudness3 dBbarely perceptible6 dBperceptible7 dBclearly perceptible

Note: round off to nearest whole number

Perceived SoundDominant frequencies affect sound perception

S: p. 747, F.17.8