# Acoustics - Sound intensity level

**URL:** <https://community.blackspectacles.com/t/acoustics-sound-intensity-level/227>\
**Category:** Project Planning & Design\
**Created:** [December 13, 2019, 3:58am UTC](https://community.blackspectacles.com/t/acoustics-sound-intensity-level/227 "2019-12-13T03:58:01Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![Artem.Melikyan](https://blackspectacles.com/uploads/images/10.png) [@Artem.Melikyan](https://community.blackspectacles.com/u/Artem.Melikyan)\
**Post date:** [December 13, 2019, 3:58am UTC](https://community.blackspectacles.com/t/acoustics-sound-intensity-level/227/1 "2019-12-13T03:58:01Z")

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Hello,

In one of the Practice Exam Form 2 there is the following question:  
A sound of 30 dB is how many times more intense than a sound of 10 db?  
Answer given:  
Each increase of 10 dB is a two-fold increase in sound level intensity. Therefor, two two-fold increases would be 10 x 10, which equals 100.

Can you, please explain how this corresponds to the statement from  
Mechanical and Electrical Equipment for Buildings 12th ed 2014, page 1028:  
“doubling a signal’s intensity raises the intensity level by 3 dB”

Thank you,

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**Author:** ![Lara](https://yyz1.discourse-cdn.com/flex029/user_avatar/community.blackspectacles.com/lara/32/12_2.png) [@Lara](https://community.blackspectacles.com/u/Lara)\
**Post date:** [December 13, 2019, 4:11pm UTC](https://community.blackspectacles.com/t/acoustics-sound-intensity-level/227/2 "2019-12-13T16:11:11Z")

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Hey Artem,

First off, welcome to the ARE community!

In regard to your question here and in [this thread](https://community.blackspectacles.com/t/wall-assemblies-terminology/228), I’m not sure off hand. Going to reach out and see if I can get you an answer on these.

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<div class="post-metadata">

**Author:** ![Lara](https://yyz1.discourse-cdn.com/flex029/user_avatar/community.blackspectacles.com/lara/32/12_2.png) [@Lara](https://community.blackspectacles.com/u/Lara)\
**Post date:** [December 13, 2019, 5:03pm UTC](https://community.blackspectacles.com/t/acoustics-sound-intensity-level/227/4 "2019-12-13T17:03:46Z")

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Hi Artem,

We’ve received questions on this one before - it’s tricky. Here’s the response from our resident architect, Heather Rivera, NCARB, AIA, LEED AP

![image](https://canada1.discourse-cdn.com/flex029/uploads/blackspectacles/original/1X/330e740e5a6d7f7179258ad8a96d7086efae5d27.png)

> “The question and answer are correct as shown. I understand the reference material says “doubled;” and we know this is confusing. In actuality, for every 10-decibel increase in the intensity of sound, loudness is 10 times greater. It is a logarithmic equation; and simply saying “doubling” makes it sound linear. I’m including a snapshot below for your reference to help explain.”