# Average Ambient Sound Level: Building Code Definition > How the IBC 2009, IFC 2009 define average ambient sound level, where the wording differs, and which chapters depend on the term. - Canonical: https://harth.build/resources/glossary/average-ambient-sound-level/ - Last updated: 2026-09-07 - Data source: Definitions quoted from the 2009 International Codes as transcribed in this site's building-codes collection, with the source chapter linked for each quotation. Usage counts are computed over the chapters hosted here, one copy per code. The [ICC code library](https://codes.iccsafe.org/codes) publishes the current model text and the [ICC adoption maps](https://www.iccsafe.org/advocacy/code-adoption-maps/) show which edition a jurisdiction has adopted; those sources control. ## Key facts | Fact | Value | | --- | --- | | Defined in | IBC 2009, IFC 2009 (2009 editions transcribed in this corpus) | | Primary source | IBC 2009 Fire Protection Systems (model text, not a jurisdiction's adopted text) | | Chapters using the term | 4 (counted across the codes hosted here) | | Wording identical across codes | Yes (compare before citing one code's wording under another) | ## Direct answer Average ambient sound level is a defined term in the International Building Code (IBC) 2009, in Fire Protection Systems. The code's own words are: “The root mean square, A-weighted sound pressure level measured over a 24-hour period, or the time any person is present, whichever time period is less.” The IFC 2009 carries the same definition word for word, so the term means the same thing in each. The term is used in 4 chapters of this corpus, most often in Fire Protection Systems (IBC 2009), Fire Protection Systems (IFC 2009), Definitions (IBC 2009). These pages transcribe the 2009 model text; verify the definition against the edition and amendments your authority having jurisdiction has adopted. Record the jurisdiction, the adopted edition, the application date and any local amendment that rewrites the definition before you use it on a live project, because a term redefined by amendment changes every requirement that depends on it. *Content and cited inputs reviewed by [Scott Barrington](https://nz.linkedin.com/in/barrington), Harth founder and architectural technology specialist · Published 2026-09-07 · Updated 2026-09-07.* ## What does this term mean? **Average Ambient Sound Level** — IBC 2009, Fire Protection Systems: > The root mean square, A-weighted sound pressure level measured over a 24-hour period, or the time any person is present, whichever time period is less. ![Labeled code-term definition diagram: Average Ambient Sound Level: Building Code Definition](https://efwwel0vyt9vy5so.public.blob.vercel-storage.com/images/glossary/average-ambient-sound-level/diagram-1344.webp) *How the IBC 2009, IFC 2009 define average ambient sound level, where the wording differs, and which chapters depend on the term.* ## What must be verified before using this guidance? Two of the I-Codes in this corpus define **Average Ambient Sound Level**, in identical words. | Code | Where it is defined | Definition | | --- | --- | --- | | IBC 2009 | [Fire Protection Systems](https://harth.build/resources/building-codes/us-states/maryland/ibc-2009/fire-protection-systems.md) | The root mean square, A-weighted sound pressure level measured over a 24-hour period, or the time any person is present, whichever time period is less. | | IFC 2009 | [Fire Protection Systems](https://harth.build/resources/building-codes/us-states/rhode-island/ifc-2009/fire-protection-systems.md) | The root mean square, A-weighted sound pressure level measured over a 24-hour period, or the time any person is present, whichever time period is less. | ## Where average ambient sound level is used in the code The term appears in 4 chapters of the 2009 I-Codes hosted here. The chapters that lean on it hardest are the ones to read next. | Chapter | Code | Mentions | | --- | --- | --- | | [Fire Protection Systems](https://harth.build/resources/building-codes/us-states/maryland/ibc-2009/fire-protection-systems.md) | IBC 2009 | 5 | | [Fire Protection Systems](https://harth.build/resources/building-codes/us-states/rhode-island/ifc-2009/fire-protection-systems.md) | IFC 2009 | 5 | | [Definitions](https://harth.build/resources/building-codes/us-states/maryland/ibc-2009/definitions.md) | IBC 2009 | 1 | | [Definitions](https://harth.build/resources/building-codes/us-states/rhode-island/ifc-2009/definitions.md) | IFC 2009 | 1 | ### The term in use How the code actually writes about average ambient sound level, quoted from the 2009 text hosted here: > The audible alarm notification appliances shall provide a sound pressure level of 15 decibels (dBA) above the average ambient sound level or 5 dBA above the maximum sound level having a duration of at least 60 seconds, whichever is greater, in every occupiable space within the building. — [IBC 2009 §907.5.2.1.1](https://harth.build/resources/building-codes/us-states/maryland/ibc-2009/fire-protection-systems.md) ## The terms average ambient sound level is built out of The definition above leans on 1 other defined term. Each carries its own code definition, and a local amendment to any of them changes what average ambient sound level covers: - **[Person](https://harth.build/resources/glossary/person.md)** — IBC 2009: An individual, heirs, executors, administrators or assigns, and also includes a firm, partnership or corporation, its or their successors or assigns, or the agent of any of the aforesaid. ## Average Ambient Sound Level: what to open, and in what order Every row is a document this term depends on. The [ICC code library](https://codes.iccsafe.org/codes) and the [ICC adoption maps](https://www.iccsafe.org/advocacy/code-adoption-maps/) cover the middle rows. | Check | Where | Confirmed | | --- | --- | --- | | Read the definition in the adopted IBC | Fire Protection Systems | | | Read the definition in the adopted IFC | Fire Protection Systems | | | Re-check the requirement that uses it | Fire Protection Systems (IBC 2009) | | | Re-check the requirement that uses it | Fire Protection Systems (IFC 2009) | | | Re-check the requirement that uses it | Definitions (IBC 2009) | | | Re-check the requirement that uses it | Definitions (IFC 2009) | | | Confirm the dependent definition | Person | | | Local amendment to any of the above | Jurisdiction's amendment list | | **A research aid, not a code determination.** The authority having jurisdiction decides which edition and which amendments apply. ## Where can you explore related guidance? - [Explore all glossary guidance](https://harth.build/resources/glossary.md) - [Person: Building Code Definition](https://harth.build/resources/glossary/person.md) - [Automatic: Building Code Definition](https://harth.build/resources/glossary/automatic.md) - [Zone: Building Code Definition](https://harth.build/resources/glossary/zone.md) - [Automatic Sprinkler System: Building Code Definition](https://harth.build/resources/glossary/automatic-sprinkler-system.md) ## Sources and method Definitions quoted from the 2009 International Codes as transcribed in this site's building-codes collection, with the source chapter linked for each quotation. Usage counts are computed over the chapters hosted here, one copy per code. The [ICC code library](https://codes.iccsafe.org/codes) publishes the current model text and the [ICC adoption maps](https://www.iccsafe.org/advocacy/code-adoption-maps/) show which edition a jurisdiction has adopted; those sources control. ### Source links - [codes.iccsafe.org](https://codes.iccsafe.org/codes) - [iccsafe.org](https://www.iccsafe.org/advocacy/code-adoption-maps/) ## Frequently asked questions ### What is the code definition of average ambient sound level? The International Building Code (IBC) 2009 defines it in Fire Protection Systems as: “The root mean square, A-weighted sound pressure level measured over a 24-hour period, or the time any person is present, whichever time period is less.” The 2009 model text is reproduced here; the definition that binds your project is the one in the edition your jurisdiction has adopted, as amended locally. ### What is the average ambient sound level? In the 2009 I-Codes hosted here it is a defined term rather than a description. The IBC 2009 states, in Fire Protection Systems: “The root mean square, A-weighted sound pressure level measured over a 24-hour period, or the time any person is present, whichever time period is less.” It is defined in IBC 2009, IFC 2009. Because it is a defined term, whatever the adopted edition says it means is what every section using it means — so check Chapter 2 of that edition and any local amendment before relying on this wording. --- - Continue in Harth (open this topic in the Harth agent): https://app.harth.build/agent?context=%2Fresources%2Fglossary%2Faverage-ambient-sound-level%2F - View this page in a browser: https://harth.build/resources/glossary/average-ambient-sound-level/ - All resources for agents: https://harth.build/llms.txt