Operator Fundamentals Online - Rational AcousticsSmaart Operator Fundamentals Online Session 6 Slide 10 Noise Pollution / Nuisance Noise Not bothering the neighbors US: No enforced

© Rational Acoustics LLC 2020 - All rights reserved

Session 6:

“All About SPL”

Operator Fundamentals Online

Smaart Operator Fundamentals OnlineSession 6

Slide 2

Jamie Anderson◦ President, Director of Training◦ [email protected]

Chris Tsanjoures◦ Smaart Product Manager, Instructor◦ [email protected]

Michael Lawrence◦ Application Support Specialist, Instructor ◦ [email protected]

Gavin Caanan◦ Training Coordinator◦ [email protected]


mailto:[email protected]





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Rational Acoustics LLC32 Crabtree Ln

Woodstock, CT 06281USA

+1 (860) 928-7828

www.RationalAcoustics.com

[email protected]

[email protected]

[email protected]

http://www.rationalacoustics.com/





Slide 4

What is SPL?

Why do we measure it?

How do we measure it?

SPL Features in Smaart v8 & Smaart SPL



Slide 5

Sound Pressure Level

An objective measure of the strength of air pressure deviations caused by a sound wave


A

T


Slide 6

Expressed in decibels

Logarithmic scale corresponds well with human hearing (% change)◦ 1 to 2 is perceived as the same increase as 100 to 200


0 dB SPL – threshold of hearing20 µPa (0.00002 Pa)

120 dB SPL – threshold of pain

1,000,000 : 1

20log(1,000,000/1)= 120 dB

H


Slide 7

SPL is an objective measurement of physical reality

Human loudness perception is extremely complex, with many factors

◦ Tonal content / balance

◦ Intelligibility

◦ THD

◦ Continuous vs Impulsive

◦ Listener Fatigue

◦ Familiarity and Preference

◦ Context & Program Material

Humans are not particularly reliable judges of SPL



Slide 8

Originally an attempt to produce a measurement that “looks like it sounds”


What is the goal?


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Sound Engineer awareness of:

◦ Consistency / Quality control

◦ Dynamic Range

◦ Fatigue

◦ Awareness of level somewhere else

Venue awareness:

◦ General / policy / courtesy

◦ Consistency

◦ Nuisance Monitoring



Slide 10

Noise Pollution / Nuisance Noise◦ Not bothering the neighbors

US: No enforced federal law◦ 42 U.S.C. §4901 et seq. (Noise Control Act of 1972)

◦ Largely focused on interstate commerce (appliances, trucks, railroads, etc)

◦ Defunded in 1981, responsibilty shifted to state / local

Many state /local regulations reference ANSI S1.4-1971◦ A-weighted measurement

◦ Ignores the LF energy that is usually the most problematic

◦ Many have poor wording: “Shall not make excessive noise” (???)



Slide 11


Courtesy of Chris Leonard

Inside Venue

Outside Venue

Vs.


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How loud is “too loud?”

When dealing with exposure, the question is twofold:

◦ - How loud?

◦ - How long?



Slide 13

OSHA PELs will not protect you from NIHL (Noise-Induced Hearing Loss)!

NIOSH: Criteria for a Recommended Standard: Occupational Noise Exposure (1998)

https://www.cdc.gov/niosh/docs/98-126/pdfs/98-126.pdf?id=10.26616/NIOSHPUB98126


OSHA Permissible Exposure Limits

Sound level

(dBA)

Duration

(Hours:Minutes)

85 16:00

90 8:00

95 4:00

100 2:00

105 1:00

110 0:30

115 0:15

120 0:07

NIOSH Recommended Exposure Limits

Sound level

(dBA)

Duration

(Hours:Minutes)

82 16:00

85 8:00

88 4:00

91 2:00

94 1:00

97 0:30

100 0:15

103 0:07

https://www.cdc.gov/niosh/docs/98-126/pdfs/98-126.pdf?id=10.26616/NIOSHPUB98126


Slide 14


dblimits.com


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SPL Slow


Slide 16


SPL Slow Leq 10


Slide 17

Leq = Equivalent Continuous Sound Pressure Level


Important for live events due to fluctuating levels

Allows a statement about level compliance

Leq 10 = 10 minute average

LAeq 10 = A-weighted

https://knowledge.ni.com/KnowledgeArticleDetails?id=kA00Z0000019N3eSAE&l=en-US

https://knowledge.ni.com/KnowledgeArticleDetails?id=kA00Z0000019N3eSAE&l=en-US


Slide 18

Choosing Hardware◦ Calibrator

◦ Mic

◦ Interface

◦ Max SPL = 140 dB SPL

◦ Why 140 dB SPL?



Slide 19


A Slow

C Slow

Peak C


Slide 20

140 dB SPL w/o clipping (THD <3%)

Check sensitivity for voltage output at 140 dB SPL◦ iSEMcon EMX-7150: 6 mV/Pa

@ 140 dB SPL: 1.2Vrms (+4 dBu)

◦ EW M30: 34 mV/Pa

@ 140 dB SPL: 6.8Vrms (+19 dBu)

◦ Shortcut: 140 – 94 dB = 46 dB (200x)


1 Pa = 94 dB SPL

Choose Mic & IO together:

https://www.youtube.com/watch?v=Xcnp5VwV9Hc

(video courtesy of iSEMcon gmbh)


Slide 21

Measurement goals dictate accuracy requirement

Consistency: accurate calibration is not important. Hit the same numbers every night.

Noise pollution: numbers need to be meaningful

Exposure: accurate calibration is extremely important.◦ Since exposure times are based on level, an error in measured level correlates directly

to an error in exposure dose



Slide 22

14min

28min

42min

57min

73min

90min


Slide 23

Class 1 vs Class 2


Type 1 vs Type 2

Standards?


Slide 24

IEC 61672-1:2013:◦ Class 1 SPL systems are required to measure over a wider frequency range than a

Class 2 system as well as meet tighter tolerances for performance criteria and documentation. The nitty-gritty details are laid out in the standards document IEC 61672

◦ The differences between Classes are not limited to microphone and interface tolerances (the entire signal acquisition chain is subject to specified tolerances), but also the format and detail with which the measurement data is logged and kept for presentation in a legal setting. It is for this reason that the UI (user interface) displaying the measurement results are also factored in Class compliance.

◦ The stipulations for documentation of SPL information outlined in the IEC standards state that specific data must be reported and documented over the duration of exposure.


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Slide 27

National Institute of Standards and Technology (NIST)

Certificate of Traceability



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Slide 30


CDC/NIOSH Study: 130 iOS apps, 3 were within 2 dB

https://blogs.cdc.gov/niosh-science-blog/2014/04/09/sound-apps/

“An analysis of 50 different apps indicated that only one was accurate to within 5 dB.”

https://www.who.int/pbd/deafness/Hearing_loss_due_to_recreational_exposure_to_loud_sounds.pdf

Clipping / overload at concert-level SPLs

https://blogs.cdc.gov/niosh-science-blog/2014/04/09/sound-apps/

https://www.who.int/pbd/deafness/Hearing_loss_due_to_recreational_exposure_to_loud_sounds.pdf


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Slide 32


10 EaZy WebsiteU.S. www.10eazy.usEverywhere Else: www.10eazy.com

http://www.10eazy.com/


Slide 33


Smaart SPL Guide◦ www.rationalacoustics.com/download/SmaartSPLQuickStartGuide.pdf

Smaart SPL Quickstart (Video) ◦ www.youtube.com/watch?v=CvlpGWwwMf0&feature=emb_logo

Calibrating for SPL with Smaart (Video)◦ www.rationalacoustics.com/support/464494-How-do-I-calibrate-Smaart-for-SPL

Smaart SPL Product Page (More Info/More Videos)◦ www.rationalacoustics.com/smaart/smaart-spl/

http://www.rationalacoustics.com/download/SmaartSPLQuickStartGuide.pdf

http://www.rationalacoustics.com/support/464494-How-do-I-calibrate-Smaart-for-SPL

www.rationalacoustics.com


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Operator Fundamentals Online - Rational AcousticsSmaart Operator Fundamentals Online Session 6 Slide 10 Noise Pollution / Nuisance Noise Not bothering the neighbors US: No enforced