Sim does not pause when changing tabs on Firefox

[brooklynlash]

Test device
Lenovo ThinkPad

Operating System
Windows 10

Browser
Firefox

Problem description
When changing through tabs with the sim running, the sim continues running and makes the "clapping" noises while in another tab.

Visuals
https://drive.google.com/file/d/1UVAbzK06crMGu3si-ndlX3gagQWnBBee/view?usp=sharing

Troubleshooting information:
!!!!! DO NOT EDIT !!!!!
Name: ‪Forces and Motion: Basics‬
URL: https://phet.colorado.edu/sims/html/forces-and-motion-basics/latest/forces-and-motion-basics_en.html
Version: 2.3.16 2019-10-28 20:07:34 UTC
Features missing: touch
Flags: pixelRatioScaling
User Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:81.0) Gecko/20100101 Firefox/81.0
Language: en-US
Window: 1728x858
Pixel Ratio: 2.2222222222222223/1
WebGL: WebGL 1.0
GLSL: WebGL GLSL ES 1.0
Vendor: Mozilla (Mozilla)
Vertex: attribs: 16 varying: 30 uniform: 4095
Texture: size: 16384 imageUnits: 16 (vertex: 16, combined: 32)
Max viewport: 32767x32767
OES_texture_float: true
Dependencies JSON: {"assert":{"sha":"928741cf","branch":"HEAD"},"axon":{"sha":"49396a5c","branch":"HEAD"},"babel":{"sha":"60856a63","branch":"master"},"brand":{"sha":"8a5077a5","branch":"HEAD"},"chipper":{"sha":"160be398","branch":"HEAD"},"dot":{"sha":"db33a2c7","branch":"HEAD"},"forces-and-motion-basics":{"sha":"83c21727","branch":"HEAD"},"joist":{"sha":"5522d8f6","branch":"HEAD"},"kite":{"sha":"dc5c4382","branch":"HEAD"},"phet-core":{"sha":"283b47e7","branch":"HEAD"},"phetcommon":{"sha":"276441fc","branch":"HEAD"},"phetmarks":{"sha":"d2ceb4af","branch":"HEAD"},"query-string-machine":{"sha":"c74e454e","branch":"HEAD"},"scenery":{"sha":"a4c5aacd","branch":"HEAD"},"scenery-phet":{"sha":"313462ef","branch":"HEAD"},"sherpa":{"sha":"dba01386","branch":"HEAD"},"sun":{"sha":"96c223b3","branch":"HEAD"},"tandem":{"sha":"e6a58f1e","branch":"HEAD"},"vibe":{"sha":"3981024e","branch":"HEAD"}}

[brooklynlash]

Only observed on Firefox, Chrome and Edge work fine. If you change tabs on Edge or Chrome while the sound is playing it continues to play but if before that it pauses the sim.

[jbphet]

I'm only guessing, because it wasn't made clear in the description, but I think this was assigned to me because it is the sound that continues when switching screens. However, this sim does not use our most recent sound library (tambo), and the older library didn't handle muting of sounds when switching screens. The right way to address this would be to upgrade FAMB to use tambo, but that doesn't seem worth the effort to me given that this is a pretty minor problem (unless I'm misunderstanding something).

@jessegreenberg is listed as the responsible developer, so I'll leave it to him to take it from here.