CLIOCLIO application: application:Room and Building AcousticsRoom and Building Acoustics

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Room and Building Acoustics

● Normative references in Room and Building acoustics● Applications:

● Measurement of impulse response● Evaluation of acoustical parameters● Speech transmission index● Wavelet analysis to room acoustics● ETF (Energy-Time-Frequency) to room acoustics● Measuring airborne sound insulation● Rating R' airborne sound insulation

● Normative related to measurement equipment

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Room and Building Acoustics● Normative references:

● ISO 18233:2006. Acoustics — Application of new measurement methods in building and room acoustics

● ISO 3382. Acoustics — Measurement of room acoustic parametersPart 1:2009. Performance spacesPart 2:2008. Reverberation time in ordinary rooms

● IEC 60268. Sound system equipmentPart 16:2003. Objective rating of speech intelligibility by speech transmission index

● ISO 140 series. Acoustics — Measurement of sound isulation in buildings and of building elements

● ISO 717 series. Acoustics — Rating of sound isulation in buildings and of building elements

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Room Acoustics● The acoustical properties of a room can be described

by means of a set of Acoustical Parameters derived from the measurement of its impulse response

● These parameters are defined in the ISO 3382 standard:● Reverberation time (EDT, RT20, RT30, RTU)● Early/late energy ratios (C50, C80, D, ts)● Sound pressure levels and Strength (G)● Background noise levels

● An important factor describing the quality related to human voice is the speech transmission index STI

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Room Impulse Response

● The room can be seen as a linear system where the Impulse Response between a sound source and a microphone can be measured using different tecniques:

● Maximum Length Sequences MLS (ISO3382 and ISO18233)

● Sine Sweeps SS (ISO3382 and ISO18233)● Impulse source (ISO3382)

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Typical on-field application

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MLS and LogChirp

● The room impulse response can be measured using a loudspeaker as source and a MLS or Sine Sweep technique

sourcemic

CLIOfw

A IN B A OUT B

room

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Measuring Impulse Responses with CLIO 10● MLS & LogChirp Analysis menu:

● size up to 512k, up to 10.8 seconds at 48 kHz● MLS:

– White stimulus– STI calculation

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Measuring Impulse Responses with CLIO 10● MLS & LogChirp Analysis menu:

● size up to 512k, up to 10.8 seconds at 48 kHz● LogChirp

– Pink stimulus– Distortion separation

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Measuring Impulse Responses with CLIO 10● MLS & LogChirp Analysis menu:

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Impulse Source

● The room impulse response can be directly measured recording the sound produced by a impulsive source as:● pistol shot● balloon popping

CLIOfw

A IN B A OUT B

sourcemic

room

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Recording of impulses with CLIO 10● The recording can be done:

● directly from the CLIO input using Leq menu● with an external recording device● the impulse recorded must be saved as a .wav file

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From Impulse to Parameters

● The Acoustical Parameters are calculated using the measured impulse responses

● The decay curve for each frequency band (octave or 1/3 of octave) of interest is generated by backward integration of the impulse response

● Background noise compensation is performed● Precise knowledge of signal level is achieved by CLIO

hardware capabilities

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Decay Analysis● CLIO allows to inspect each band decay

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Acoustical Parameters● CLIO show each parameter vs frequency

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STI (Speech Transmission Index)● If the impulse response is measured using the MLS

tecnique it is possible also to calculate the Speech Transmission Index (D. Rife, "Modulation Transfer Function Measurement with Maximum-Length Sequences", JAES Volume 40 Issue 10 pp. 779-790; October 1992)

-----------------------------------------------------STI index-----------------------------------------------------Oct.Band 125 250 500 1k 2k 4k 8kf1=0.63 0.745 0.811 0.761 0.813 0.829 0.880 0.972f2=0.80 0.686 0.739 0.688 0.747 0.755 0.801 0.890f3=1.00 0.644 0.686 0.633 0.699 0.699 0.741 0.827f4=1.25 0.579 0.604 0.556 0.635 0.616 0.651 0.733f5=1.60 0.523 0.536 0.510 0.592 0.553 0.581 0.661f6=2.00 0.477 0.478 0.485 0.558 0.501 0.521 0.602f7=2.50 0.415 0.404 0.458 0.525 0.431 0.438 0.527f8=3.15 0.345 0.338 0.434 0.504 0.362 0.353 0.461f9=4.00 0.298 0.302 0.427 0.455 0.235 0.166 0.373f10=5.00 0.353 0.260 0.421 0.405 0.204 0.090 0.361f11=6.30 0.442 0.144 0.368 0.415 0.317 0.363 0.462f12=8.00 0.563 0.493 0.447 0.493 0.450 0.548 0.650f13=10.00 0.400 0.392 0.379 0.495 0.403 0.505 0.687f14=12.50 0.372 0.298 0.340 0.477 0.272 0.379 0.507-----------------------------------------------------MTI 0.489 0.463 0.493 0.558 0.473 0.501 0.623STI=0.512 ALcons=10.6% rated Fair

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Wavelet Analysis

● The wavelet analisys can be used as powerful tool for room acoustics

● The measured impulse response can be inspected in the time-frequency plane

● In the following example we see the effects of controlling reverberation and resonant modes by means of absorption and diffusion

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Wavelet Analysis0

-5

-10

-15

-20

-25

dB

0 32 64 96 128 160 192 224 256 288 320 ms

100

1k

10k

20k

40

Hz

CLIO

Wavelet Analysis 9-20-2008 4.31.33 PM

Time-Frequency Energy Normalized Q 3.000 BW 0.333 octaves

File:

320cm – nessun trattamento

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Wavelet Analysis0

-5

-10

-15

-20

-25

dB

0 32 64 96 128 160 192 224 256 288 320 ms

100

1k

10k

20k

40

Hz

CLIO

Wavelet Analysis 9-20-2008 4.30.18 PM

Time-Frequency Energy Normalized Q 3.000 BW 0.333 octaves

File:

320cm – full

Diminuzione riverberazioneDiminuzione riverberazionee controllo modalee controllo modale

tramite assorbimento tramite assorbimento e diffusionee diffusione

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Room Analysis Example

No absorption With absorbing materials

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ETF (Energy Time Frequency) AnalysisNo absorption With absorbing materials

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Building AcousticsAirborne sound insulation

Measurement of the Apparent Sound Reduction Index R'

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Building AcousticsMeasurement of the Apparent Sound Reduction Index R'

R' measurements depend on the following factors:● L1 : Emitting SPL ● L2 : Receiving SPL● Background noise● S : Dividing surface● A: Receiving absorption coefficient

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Building AcousticsMeasurement of the Apparent Sound Reduction Index R'

100 1000 100000

20

40

60

80

100

120

SPL

BackgroundEmittingReceiving

100 1000 100000

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

RT 60

AveragePos 1Pos 2Pos 3Pos 4Pos 5Pos 6

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Building AcousticsRating of the Apparent Sound Reduction Index R'

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Room and Building AcousticsMeasurement Equipment

● Normative references:● IEC 61672:2003. Electroacoustics — Sound level

meters. (replacing former IEC 651, Sound level meters and IEC 804, Integrating-averaging sound level meters)

● IEC 61260:2001. Electroacoustics — Octave-band and fractional-octave-band filters

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Room and Building AcousticsMeasurement Equipment

Laboratory and engineering tests

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Room and Building AcousticsMeasurement Equipment

Class 1 certified equipment

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