APPLICATION NOTESound Insulation
with the XL2 Sound Level Meter

This application note describes how to measure sound insulation. This includes airborne and impact sound insulation between two rooms and the airborne sound insulation of façades
using sound pressure measurements. All measurements are performed by the XL2 Sound Level Meter and documented using
the Sound Insulation Reporter software in accordance with thestandard series ISO 16283.
The sound insulation is calculated by combining multiple soundpressure level and reverberation time measurements. The measured frequency range is typically from 50 Hz to 5 kHz. The measured airborne sound insulation is frequency-dependent but canbe converted into a single number, the sound reduction index, tocharacterize the acoustic performance.
This application note applies to rooms with a volume between
25 m3 and 250 m3. Special methods apply to smaller rooms.

XL2-TA
Sound Level Meter

Index
1. Getting Ready2

2. Airborne Sound Insulation between two Rooms

3

3. Impact Sound Insulation

11

4. Airborne Sound Insulation of Facades

17

5. Sound Insulation Reporter Software24

6. Know How

25

7. Sound Insulation according ASTM

28

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1. Getting Ready
Instrument Configuration
The sound level meter shall meet the requirements of a class 1 instrument in accordance with theIEC 61672-1 standard. The recommended configuration consists of• XL2 Sound Level Meter or
XL2-TA Sound Level Meter for legally traceable measurements(=XL2 with Type Approval Option installed)• Optional Extended Acoustic Pack installed in XL2(required for reverberation time measurement in 1/3 octave resolution• XL2 Sound Insulation Option (permanently installed) or Sound Insulation Reporter 365 (annual
subscription service)• M2230 Measurement Microphone• ASD Cable, 5 m• NTi Audio Class 1 Sound Calibrator• Lightweight Microphone Tripod• DS3 Dodecahedron Speaker• Tripod for DS3 Dodecahedron Speaker• PA3 Power Amplifier• Tapping Machine TM3• Computer/Tablet with Sound Insulation Reporter Software

Calibration
At the beginning and at the end of each measurement day, the entire sound pressure level measurement system shall be checked with the NTi Audio Class 1 Sound Calibrator. This calibrator
meets the class 1 requirements specified in the standard IEC 60942.

Notes:• The sound pressure level measuring system shall be calibrated at intervals not exceeding two
years.
• Wear hearing protection for all measurements.

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APPLICATION NOTE

2. Airborne Sound Insulation between two Rooms
Measuring the airborne sound insulation between two room in a building requires the following
measurements:• Sound pressure level in the sending room
• Sound pressure level in the receiving room
• Background noise level in the receiving room
− Reverberation time in the receiving room

The basic concept of sound insulation measurements is to play a pink noise test signal by the
Dodecahedron Speaker DS3 in the sending room. This generates a diffuse sound field in the room.
The generated sound is transmitted through the common partition into the receiving room, where
also a diffuse sound field throughout the room is assumed.
First the sound pressure level spectrum is measured in the sending room at multiple microphone
positions and averaged. The same is repeated for the receiving room - any disturbing backgroundnoise is deducted.
The difference indicates the insulation for the first speaker position. The same procedure is repeated for a second speaker position. Additional reverberation time measurements are carried out
in the receiving room for corrections - e.g. the receiving room level is higher at very reverberant
rooms.

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2.1 Getting Started
Room Selection
Airborne sound insulation is measured between two rooms. One room is chosen as the sending
room and the other one is chosen as the receiving room. In case the volumes of the two rooms
differ, then the smaller room shall be used as the receiving room. If one of the rooms is box-shaped
and the other has a more complicated geometry, the box-shaped room shall be used as the receiving room.

L1

Sending Room

L2

Receiving Room

Selecting Sending Room and Receiving Roomwww.nti-audio.com

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APPLICATION NOTE

Speaker Position• Position the Dodecahedron Speaker DS3 in the sending room.
• The measurements have to be carried out with at least two different speaker positions.
• Choose speaker position 1 at least 0.5 m from any room boundary and at least 1.0 m fromthe separating partition. Position 2 shall be similarly chosen, plus be in a different plane relative to the room boundaries, and with a minimum 1.4 m distance to position 1. In case theseparation partition is a floor and the speaker is in the upper room, then the Dodecahedron
Speaker DS3 has to be at least 1 m above the floor. The distances are measured from thecenter of the individual driver unit of the Dodecahedron Speaker DS3 closest to the boundaryor other speaker position.

L1

Source Pos. 1
min.
0.5 m

L2

min. 1.0 m

min. 1.4 m

Source Pos. 2

Sending Room

Receiving Room

Positions of the test signal source for the sound level measurements

Test Signal Level• Reduce level setting on PA3 Power Amplifier to minimum.
• Power on PA3 Power Amplifier.
• Select the signal source “EQ Pink” for a flat acoustic response in the source room. Go for“Pink” in case a higher level is required.
• Press “Signal ON” and increase the level until it is minimum of 6 dB – better 10 dB - higher inthe receiving room than the background noise (in each frequency band from 50 Hz to 5000
Hz). In case this is not possible, then the Sound Insulation Reporter software will automatically apply corrections in accordance with the standard.

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APPLICATION NOTE

2.2 Background Noise Level in Receiving Room
Preparation• Select the RTA page in the SLMeter function on the XL2Sound Level Meter.
• Select 1/3 octave measurement resolution.
• It’s recommended to vacate the room during the measurement so that any noise generated by the operator will notaffect the measurement.

Background Noise Spectrum in
the Receiving RoomMeasurement• Measure the background noise LZeq in the receiving room for 15 seconds. In case the background noise is not steady and continuous, then a longer measurement period shall be applied, e.g. 30 seconds.
• Store the individual readings on the XL2.

Mic Position

Sending Room

Receiving RoomMeasure the Background Noise Level Lb in the Receiving Roomwww.nti-audio.com

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2.3 Sound Pressure Levels at speaker position 1
Preparation
Define five microphone positions in the sending and receiving room, distributed within the maximum permitted space
throughout each room. The positions shall be in a different
plane relative to the room boundaries and shall not form aregular grid. For example, mark the positions on the floor witha tape. The following minimum distances apply:• 0.7 m between microphone positions• 0.5 m from any room boundary• 1.0 m between any microphone position and the speaker

Noise Spectrum in the Sending RoomIt’s recommended to vacate the room during the level measurement as the operator introduces additional absorption.

Measurements in Sending & Receiving Room• Measure the sound level spectrum LZeq in the sending
and receiving room at each position for a measurement
period of 15 seconds.
• Store the individual readings on the XL2.

Noise Spectrum in the Receiving Room
Source Pos. 1
min.
0.5 m

min.
1.0 m

L1

L2
Mic Pos. 1

Mic Pos. 1
Mic Pos. 2

Mic Pos. 2
min.
0.7 m

Mic Pos. 3

Mic Pos. 3

Mic Pos. 4

Mic Pos. 4

Mic Pos. 5

Mic Pos. 5
Sending Room

Receiving RoomMeasure the Sound Levels in the Sending and Receiving Room with the Speaker at Position 1

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APPLICATION NOTE

2.4 Sound Pressure Levels at speaker position 2
Move the Dodecahedron Speaker DS3 to source position 2.

Measurements in Sending Room• Measure the sound level spectrum LZeq in the sending
room at each position for a measurement period of 15
seconds.
• Store the individual readings on the XL2.

Noise Spectrum in the Sending RoomMeasurements in Receiving Room• Measure the sound level spectrum LZeq in the receivingroom at each position for a measurement period of 15
seconds.
• Store the readings on the XL2.

Noise Spectrum in the Receiving Room
L1

L2
Mic Pos. 1

Mic Pos. 1
Mic Pos. 2

Mic Pos. 2

Mic Pos. 3

Mic Pos. 3
Source Pos. 2

Mic Pos. 4

Mic Pos. 4

Mic Pos. 5

Mic Pos. 5
Sending Room

Receiving RoomMeasure the Sound Levels in the Sending and Receiving Room with the Speaker at Position 2

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APPLICATION NOTE

2.5 Reverberation Time in Receiving Room
Preparation• Move the Dodecahedron Speaker DS3 to the receiving
room.
• Select three microphone positions in the receiving room.
• Select the RT60 measurement function on the XL2 Sound
Level Meter.
• Select the 1/3 octave resolution on the XL2.

Reverberation Time T

Measurement• Start the measurement on the XL2.
• Start / stop the test signal.
Guideline: Set the on/off cycle time for the signal longer than the expected reverberation time.
• Measure at least two decays per position - better three decays.
• Stop the measurement on the XL2.
• Store the readings on the XL2.

L1

L2
SourceMic Pos. 1

Mic Pos. 2
Mic Pos. 3

Sending Room

Receiving RoomMeasure the Reverberation Time T in the Receiving Roomwww.nti-audio.com

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APPLICATION NOTE

2.6 Data Analysis and Reporting
Verify and document all readings by using the Sound Insulation Reporter software. This is a PCSoftware dedicated for building acoustics professionals. Load all measurement records into thesoftware and generate the sound insulation report. The software calculates the weighted ratings
based on the reference curve shifting method in accordance with the ISO 717-1 standard.

Calculation formulas:• D = L1 – L2
• Dn = D - 10 log (A / 10)• DnT = D + 10 log (T / 0.5)
• R’ = D + 10 log (S / A)
• A = 0.16 * V / T

AEquivalent absorption area of the receiving room [m2]D

Level difference between the sending and receiving room [dB]Dn

Normalized level difference [dB] (the level difference D is standardized to theequivalent absorption area of 10 m2 in the receiving room)

DnTStandardized level difference [dB] (the level difference D is standardized to the
0.5 seconds reference value of the reverberation time in the receiving room)

DnT,w

Weighted standardized level difference (is the value of the reference curve at
500 Hz after shifting the reference curve) [dB]

L1

Sound pressure level in the sending room [dB]

L2Sound pressure level in the receiving room [dB]R’Apparent sound reduction index of field measurement [dB]R’w

Weighted apparent sound reduction index [dB] (is the value of the reference
curve at 500 Hz after shifting the reference curve)

S

Partition area between the sending and receiving room [m2]T

Reverberation time in the receiving room [s]V

Volume of the receiving room in [m3]www.nti-audio.com

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APPLICATION NOTE

3. Impact Sound Insulation
Two different source types can be used for the measurement of the impact sound insulation• Tapping Machineused to assess a variety of light, hard impacts such as footsteps from walkers wearing hardheeled footwear or dropped objects• Rubber Ball
used to assess heavy, soft impacts such as from walkers in bare feet or children jumping, as
well as quantifying absolute values that can be related to human disturbanceHere the measurement with the Tapping Machine is described.

Measuring the impact sound insulation requires the following measurements:• Background noise level in the receiving room
• Sound pressure level in the receiving room
• Reverberation time in the receiving room

3.1 Getting Started
Room Selection
Typically, the impact sound insulation is measured between two rooms above each other. The
Tapping Machine TM3 is positioned in the upper room, the source room. The measurements are
performed in the lower room, the receiving room.

Source Position• Position the Tapping Machine TM3 in the sending room.
• The measurements have to be carried out with at least four different source positions. The
minimum distance to any wall shall be 0.5 m. In case of floor constructions with beams thetapping machine should be placed in an angel of 45° to the direction of the beams.

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APPLICATION NOTE

3.2 Background Noise Level in Receiving Room
Preparation• Select the RTA page in the SLMeter function on the XL2Sound Level Meter.
• Select 1/3 octave measurement resolution.
• It’s recommended to vacate the room during the measurement so that any noise generated by the operator will notaffect the measurement.

Background Noise Spectrum in
the Receiving RoomMeasurement• Measure the background noise LZeq in the receiving room for 15 seconds. In case the background noise is not steady and continuous, then a longer measurement period shall be applied, e.g. 30 seconds.
• Store the readings on the XL2.

Sending Room

Mic Position

Receiving RoomMeasure the Background Noise Level Lb in the Receiving Room - Side View

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3.3 Sound Pressure Level in Receiving Room
Preparation
The Tapping Machine TM3 shall be placed in at least four different positions randomly distributedon the floor under test. The hammer connecting line should be at 45° to the direction of any applicable beams or ribs in the floor. Each source position shall have a minimum distance of 0.5 m
the any room boundary.

Define four microphone positions, distributed within the maximum permitted space throughout thereceiving room. Use at least two microphone positions for each source position. The microphone
positions shall be in a different plane relative to the room boundaries and shall not form a regulargrid. For example, mark the positions on the floor with a tape. The following minimum distances
apply:• 0.7 m between microphone positions• 0.5 m from any room boundary• 1.0 m from the partition being excited by the impact source.

It’s recommended to vacate the room during the level measurement as the operator introduces
additional absorption.

Measurements• Measure the sound level spectrum LZeq at each microphone position for a measurement period of 15 seconds.
• Store the individual readings in the XL2 for post calculation of the sound insulation.

Noise Spectrum in the Receiving Roomwww.nti-audio.com

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L1

APPLICATION NOTE

Source Pos. 1

Source Pos. 2
Source Pos. 3

Source Pos. 4
Source RoomTapping Machine Positions in Source Room - Top View

L2
Mic Pos. 1
Mic Pos. 2

Mic Pos. 3

Mic Pos. 4

Receiving RoomMeasure the Sound Levels in the Receiving Room with Tapping Machine at Source Position 1 - Top View

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3.4 Reverberation Time in Receiving Room
Preparation• Move the Dodecahedron Speaker DS3 to the receiving
room.
• Select three microphone positions in the receiving room.
• Select the RT60 measurement function on the XL2 Sound
Level Meter.
• Select the 1/3 octave resolution on the XL2.

Reverberation Time T

Measurement• Start the measurement on the XL2.
• Start / stop the test signal.
Guideline: Set the on/off cycle time for the signal longer than the expected reverberation time.
• Measure at least two decays per position - better three decays.
• Stop the measurement on the XL2.
• Store the readings on the XL2.

L2
SourceMic Pos. 1

Mic Pos. 2
Mic Pos. 3

Receiving RoomMeasure the Reverberation Time T in the Receiving Roomwww.nti-audio.com

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APPLICATION NOTE

3.5 Data Analysis and Reporting
Verify and document all readings by using the Sound Insulation Reporter software. This is a PCSoftware dedicated for building acoustics professionals. Load all measurement records into thesoftware and generate the sound insulation report. The software calculates the weighted ratings
based on the reference curve shifting method in accordance with the ISO 717-2 standard.

Calculation formulas:• L’n = Li + 10 log (A / 10)• L’nT = Li – 10 log (T / 0.5)
• A = 0.16 * V / T

AEquivalent absorption area of the receiving room [m2]Li

Impact sound pressure level in the receiving room [dB]

L’nNormalized sound pressure level [dB]Ln,w

Weighted normalized sound pressure level [dB] (is the value of the reference
curve at 500 Hz after shifting the reference curve)

L’nT

Standardized impact sound pressure level [dB]

L’nT,w

Weighted standardized impact sound pressure level [dB] (is the value of thereference curve at 500 Hz after shifting the reference curve)

T

Reverberation time in the receiving room [s]V

Volume of the receiving room in [m3]www.nti-audio.com

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APPLICATION NOTE

4. Airborne Sound Insulation of Facades
Two measurement methods are distinguished for the measurement of the airborne sound insulation of facades• Element method− for sound insulation measurements of façade elements, e.g. windows− The purpose of the measurement is to obtain sound reduction index results for comparison
with laboratory measurements,• Global method− provides the real sound level reduction of a facade under test in a given place relative to a
position 2 m in front of the façade− preferred method for sound insulation measurements of whole facades including all flanking paths− The result cannot be compared with that of laboratory measurements.

Here the global measurement method is described.

Measuring the airborne sound insulation of facades requires the following measurements:• Background noise level in the receiving room
• Sound pressure level in front of facade• Sound pressure level in the receiving room
• Reverberation time in the receiving room

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4.1 Getting Started
Speaker Position• Position the Dodecahedron Speaker DS3 outdoors in front of the facade. The distance D shallbe at least 5 m.
• The angle of sound incidence at the facade shall be 45° +/- 5°. The distance from the loudspeaker to the center of the facade under test shall be at least 7 m.
• The sending sound pressure level is measured 2 m in front of the facade.
• The measurements may be carried out at one or multiple speaker positions. Several speaker
positions are required at very large rooms or in case the room has two or more outside walls.

L2

Receiving Room

m

in

im

um

7

m

L1

45°

SourceOutdoor Sending Area

Test Signal Level• Start the pink noise test signal at a low level.
• Increase the level until it is minimum of 6 dB – better 10 dB - higher in the receiving room
than the background noise (in each frequency band from 50 Hz to 5000 Hz). In case this is
not possible, then the Sound Insulation Reporter software will automatically apply correctionsin accordance with the standard.

www.nti-audio.com

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APPLICATION NOTE

4.2 Background Noise Level in Receiving Room
Preparation• Select the RTA page in the SLMeter function on the XL2Sound Level Meter.
• Select 1/3 octave measurement resolution.
• It’s recommended to vacate the room during the measurement so that any noise generated by the operator will notaffect the measurement.

Background Noise Spectrum in
the Receiving RoomMeasurement• Measure the background noise LZeq in the receiving room for 15 seconds. In case the background noise is not steady and continuous, then a longer measurement period shall be applied, e.g. 30 seconds.
• Store the readings on the XL2.

L1

L2

Mic Position

Outdoor Area

Receiving RoomMeasure the Background Noise Level Lb in the Receiving Room - Top View

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APPLICATION NOTE

4.3 Outdoor Sound Pressure Level in front of Facade
Preparation
The sending sound pressure level is measured outdoor at 2 m (+/- 0.2m) in front of the facadesurface center under test. The height of the microphone is 1.5 m above the receiving room floor.

Measurements• Measure the sending sound level spectrum LZeq for ameasurement period of 15 seconds.
• Store the readings on the XL2.

Noise Spectrum in front of Facade

L1

L2

2m

Mic Pos.
Receiving Room

45°

SourceOutdoor Sending Area
Measure the Sound Level in the Outdoor Sending Area - Side View

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4.4 Sound Pressure Level in Receiving Room
Preparation
Define five microphone positions in the sending and receiving room, distributed within the maximum permitted space throughout each room. The positions shall be in a different plane relative
to the room boundaries and shall not form a regular grid. For example, mark the positions on thefloor with a tape. The following minimum distances apply:• 0.7 m between microphone positions• 0.5 m from any room boundary• 1.0 m between any microphone position and the speakerIt’s recommended to vacate the room during the level measurement as the operator introduces
additional absorption

Measurements• Measure the sending and receiving sound level spectrum
LZeq at each microphone position for a measurement
period of 15 seconds.
• Store the readings on the XL2.

Noise Spectrum in the Receiving Room

L1

L2
Mic Pos. 1
Mic Pos. 2

Mic Pos. 3

Mic Pos. 4
Mic Pos. 5
Outdoor Area

Receiving RoomMeasure the Sound Levels in the Receiving Room - Top View

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APPLICATION NOTE

4.5 Reverberation Time in Receiving Room
Preparation• Move the Dodecahedron Speaker DS3 to the receiving
room.
• Select three microphone positions in the receiving room.
• Select the RT60 measurement function on the XL2 Sound
Level Meter.
• Select the 1/3 octave resolution on the XL2.

Reverberation Time T

Measurement• Start the measurement on the XL2.
• Start / stop the test signal.
Guideline: Set the on/off cycle time for the signal longer than the expected reverberation time.
• Measure at least two decays per position - better three decays.
• Stop the measurement on the XL2.
• Store the readings on the XL2.

L1

L2
SourceMic Pos. 1

Mic Pos. 2
Mic Pos. 3

Outdoor Area

Receiving RoomMeasure the Reverberation Time T - Top View

www.nti-audio.com

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APPLICATION NOTE

4.6 Data Analysis and Reporting
Verify and document all readings by using the Sound Insulation Reporter software. This is a PCSoftware dedicated for building acoustics professionals. Load all measurement records into thesoftware and generate the sound insulation report. The software calculates the weighted ratings
based on the reference curve shifting method in accordance with the ISO 717-1 standard.

Calculation formulas:• D2m = L1,2m – L2
• D2m,n = D2m - 10 log (A / 10)• D2m,nT = D2m + 10 log (T / 0.5)
• R’45° = D + 10 lg (S / A) - 1.5• A = 0.16 * V / T

AEquivalent absorption area of the receiving room [m2]D

Difference between facade level and receiving room level using element
method [dB]D2m

Difference between level 2 m in front of facade and receiving room level [dB]D2m,nNormalized level difference [dB] (the level difference D is standardized to theequivalent absorption area of 10 m2 in the receiving room)

D2m,nT

Standardized level difference [dB] (the level difference D is standardized to the
0.5 seconds reference value of the reverberation time in the receiving room)

DnT,w

Weighted standardized level difference (is the value of the reference curve at
500 Hz after shifting the reference curve) [dB]

L1,2m

Sound pressure level measured 2 m in front of facade [dB]

L2Sound pressure level in the receiving room [dB]R’45°

Apparent sound reduction index of field measurement using element method[dB]

R’45°,w

Weighted apparent sound reduction index using element method [dB] (is thevalue of the reference curve at 500 Hz after shifting the reference curve)

S

Partition area between the outdoor area and receiving room [m2]T

Reverberation time in the receiving room [s]V

Volume of the receiving room in [m3]www.nti-audio.com

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APPLICATION NOTE

5. Sound Insulation Reporter Software

Sound Insulation Reporter - Airborne Sample Reportwww.nti-audio.com

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APPLICATION NOTE

6. Know How
6.1 Diffuse Sound Field
One of the assumptions commonly made in sound insulation measurements is that the sound field
in a room can be considered as being diffuse (= the sound energy density is uniform throughout
the space). This is not strictly correct because diffuse sound fields don’t occur in real box-shaped
rooms with stationary surfaces and absorbent boundaries. However, in the field situation there aresome rooms in which there are close approximations to a diffuse sound field in the mid and highfrequency ranges. In frequency bands lower than about 400 Hz in general and especially lower than
100 Hz, no diffuse-field conditions in the test room can be expected especially when room volumesof 50 m3 or less are considered.
The preceding described measurement procedure allows for measurements to be taken without
any knowledge as to whether the sound field can be considered as diffuse or non-diffuse.

6.2 Source Position
For airborne sound insulation measurements in non-diffuse sound fields, it is necessary to excite
the majority of the modes in the source room. For this reason, loudspeaker positions near thecorners are used in box-shaped rooms as well as other shapes of room. Many more modes are
excited by the source in a corner position than a central point. In addition, it is necessary to takeaverage measurement from more than one source position. (Sound Insulation by Carl Hopkins,
2007, Elsevier & Revision of international standards by Carl Hopkins, 2015, Elsevier)6.3 Sound Reduction Index R
The sound insulation capabilities of a particular wall, ceiling, or component can be measured in alaboratory, and a sound reduction index R assigned to it. For such laboratory measurements it’s
important that the sound transmitted from the sending room into the receiving room not directly
through the partition under test (e.g. via the side walls) is at least 15 dB below the sound transmitted directly through the partition.

Sending Room

L1

L2

Partition

Side wall

Side wall

Receiving RoomDefault room layout

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APPLICATION NOTE

6.4 Apparent Sound Reduction Index R’
In an actual building (outside of the laboratory), sound may find a way around the main roomseparating partition e.g. through a window or an electric wiring channel; the sound level in the receiving room is not just the sound transmitted through the partition itself. Therefore, the so-called
Apparent Sound Reduction Index R’ is measured.

6.5 Normalized level difference Dn
The normalized level difference Dn is used for situations where there is no common partition areaor where the partition area is not easily determined (e.g. fan opening, ventilation, etc.). The soundpressure level is measured in the sending and receiving room and the difference D calculated. As
the level in the receiving room depends on the absorption within the room, the level difference isnormalized with the actual absorption area in the receiving room in relation to a reference absorption area of 10 m2. In relation to the sound insulation index R, a normalized level difference Dn of,for example, 40 dB can be seen as a wall area of 10 m2 with R = 40 dB.

L2

Receiving Room
L1

Sending Room
Room layout without common partition area

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APPLICATION NOTE

6.6 Standardized level difference DnT
The standardized level difference describes the sound insulation between two rooms. This term
is commonly specified in local standards with minimum requirements. The sound pressure level ismeasured in the sending and receiving room and the difference D calculated. As the level in thereceiving room depends on the reverberation time T in the room, the level difference is standardized to the measured reverberation time in the receiving room in relation to a reference reverberation time of 0.5 seconds.

6.7 Related Standards
ISO 16283-1

Acoustics — Field measurement of sound insulation in buildings and of building elements — Part 1: Airborne sound insulation

ISO 16283-2

Acoustics — Field measurement of sound insulation in buildings and of building elements — Part 2: Impact sound insulation

ISO 16283-3

Acoustics — Field measurement of sound insulation in buildings and of building elements — Part 3: Façade sound insulation

ISO 717-1

Acoustics — Rating of sound insulation in buildings and of building elements— Part 1: Airborne sound insulation

ISO 717-2

Acoustics — Rating of sound insulation in buildings and of building elements— Part 2: Impact sound insulation

IEC 61672-1

Electroacoustics – Sound level meters – Part 1: Specifications

IEC 61260-1

Electroacoustics – Octave-band and fractional-octave-band filters – Part 1:
Specifications

IEC 60942

Electroacoustics - Sound calibrators

ISO 3382-2

Acoustics — Measurement of room acoustic parameters — Part 2: Reverberation time in ordinary rooms

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APPLICATION NOTE

7. Sound Insulation according ASTM
7.1 Airborne Sound Insulation
ASTM specifies the measurement of airborne sound insulation between two rooms in the standards E336 and E413.

Calculation formulas:• NR = L1 - L2
• NNR = NR + 10 log (T / 0.5)
• ATL = NR + 10 log (S / A)
• A = 55.26 * V / (c * T)
• c = 20.047 * SQRT (273.15 + t)

ATL

Apparent transmission loss [dB]

ASTCApparent sound transmission class [dB] (single number rating obtained byapplying the classification procedure of Classification E413 to apparent
transmission loss data)

A

Sound absorption in the receiving room [m2]c

Speed of sound [m/s]

L1

Sound pressure level in the sending room [dB]

L2Sound pressure level in the receiving room [dB]NR

Noise reduction between the sending and receiving room [dB]

NIC

Noise isolation class [dB] (a single-number rating calculated in accordancewith Classification E413 using measured values of noise reduction)

NNR

Normalized noise reduction [dB] (the level difference D is standardized to the
0.5 seconds reference value of the reverberation time in the receiving room)

NNIC

Normalized noise isolation class [dB] (a single-number rating calculated inaccordance with Classification E413 using measured values of normalized
noise reduction)

S

Partition area between the sending and receiving room [m2]t

Room temperature [°C]T

Reverberation time in the receiving room [s]V

Volume of the receiving room in [m3]www.nti-audio.com

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7.2 Impact Sound Insulation
ASTM specifies the measurement of impact sound insulation in the standards E1007 and E989.

Calculation formulas:• ANISPL = ISPL - 10 log (10 / A)
• RTNISPL = ISPL - 10 log (T / 0.5)
• A = 55.26 * V / (c * T)
• c = 20.047 * SQRT (273.15 + t)

A

Sound absorption in the receiving room [m2]

AIIC

Apparent impact insulation class [dB] (a single-number rating derived fromvalues of ANISPL in accordance with Classification E989, formerly FIIC forfield impact insulation class)

ANISPL

Absorption normalized impact sound pressure level [dB]c

Speed of sound [m/s]

ISPL

Impact sound pressure level produced in the receiving room by the operationof the standard tapping machine on a floor-ceiling assembly [dB]ISRImpact sound rating [dB] (a single-number rating derived from values of ISPLin accordance with Classification E989)

NISR

Normalized impact sound rating [dB] (a single-number rating derived fromvalues of RTNISPL in accordance with Classification E989)

RTNISPL

Reverberation time normalized impact sound pressure level [dB]t

Room temperature [°C]T

Reverberation time in the receiving room [s]V

Volume of the receiving room in [m3]www.nti-audio.com

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Sound Insulation

APPLICATION NOTE

7.3 Facade Sound Insulation
ASTM specifies the measurement of facade sound insulation in the standards E966 and E1332.

Calculation formulas:• OINR = Lfree - Lin• OINR = L2m - Lin - 2 dB
• OINR = Lflush - Lin - 5 dB
• AOITL = OINR + 10 log (S * cos Q / A) + 6 dB
• A = 55.26 * V / (c * T)
• c = 20.047 * SQRT (273.15 + t)

A

Sound absorption in the receiving room [m2]AOITC

Apparent outdoor-indoor transmission class [dB] (a single-number rating calculated in accordance with Classification E1332 using measured values ofapparent outdoor-indoor transmission loss)

AOITL

Apparent outdoor-indoor transmission loss [dB]c

Speed of sound [m/s]

L2m

Nearby microphone method - sound pressure level measured 2 m in front of
facade [dB]

LflushFlush microphone method - sound pressure level measured very close to thefacade [dB]

Lfree

Calibrated source method - sound pressure level of the source calibrated infree-field environment at the same distance that the source is to be facade
[dB]

Lin

Sound pressure level in the receiving room [dB]

OINIC

Outdoor-indoor noise isolation class [dB] (a single-number rating calculated
in accordance with Classification E1332 using values of outdoor-indoor noise
reduction)

OINR

Outdoor-indoor noise reduction [dB]S

Partition area between the outdoor area and receiving room [m2]t

Room temperature [°C]T

Reverberation time in the receiving room [s]QAngle of incidence of test sound [°]V

Volume of the receiving room in [m3]www.nti-audio.com

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Sound Insulation

APPLICATION NOTE

7.4 Related Standards
ASTM E336

Standard Test Method for Measurement of Airborne Sound Attenuation between Rooms in Buildings

ASTM E413

Classification for Rating Sound Insulation

ASTM E1007

Standard Test Method for Field Measurement of Tapping Machine Impact
Sound Transmission Through Floor-Ceiling Assemblies and Associated Support Structures

ASTM E989

Standard Classification for Determination of Single-Number Metrics for Impact Noise

ASTM E966

Standard Guide for Field Measurements of Airborne Sound Attenuation of
Building Facades and Facade Elements

ASTM E1332

Standard Classification for Rating Outdoor-Indoor Sound Attenuation

ANSI/ASA
S1.4 / Part 1

American National Standard Electroacoustics - Sound Level Meters - Part 1:
Specifications (a nationally adopted international standard IEC 61672-1)

ANSI/ASA
S1.11 / Part 1

Electroacoustics - Octave-band and Fractional-octave-band Filters -Part
2: Pattern-evaluation Tests (a nationally adopted international standard IEC
61260-1)

ANSI/ASA
S1.40

American National Standard Specifications and Verification Procedures forSound Calibrators

IEC 60942

Electroacoustics - Sound calibrators

ASTM E2235

Standard Test Method for Determination of Decay Rates for Use in Sound
Insulation Test Methods

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