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[Matthew Paul Thomas <mpt@xxxxxxxxxxxxx>]

"At 80 dB(A) exposure time shall be limited to 40 hours/week, whereas at
89 dB(A) exposure time shall be limited to 5 hours/week. For other
exposure levels a linear intra- and extrapolation applies."

I'll put this here for others to check while I do the rest of the
design:

maximum time per week = a function of volume
40 h = f(80 dB(A))
5 h = f(89 dB(A))
linear intra- and extrapolation ∴ maximum time per week = m × volume + c
m = (40h – 5h) ÷ (80 dB(A) – 89 dB(A)) = 35 h ÷ –9 dB(A) = –3.889 h/dB(A)

40h = –3.889 h/dB(A) × 80 dB(A) + c
c = 40h – (–3.889 h/dB(A) × 80 dB(A)) = 351.111 h

∴ maximum time per week = –3.889 h/dB(A) × volume + 351.111 h.

A quick graph of this formula looks right, at least.

** Attachment added: "graph of the formula"
   https://bugs.launchpad.net/ubuntu-ux/+bug/1373404/+attachment/4220266/+files/EU%20volume%20limits%20graph.png

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https://bugs.launchpad.net/bugs/1373404

Title:
  No warning of high volume level

Status in Ubuntu UX bugs:
  In Progress
Status in “unity8” package in Ubuntu:
  Confirmed

Bug description:
  The EU has a legal requirement for personal music players to prevent hearing damage.
  http://eur-lex.europa.eu/legal-content/EN/TXT/HTML/?uri=CELEX:32009D0490&rid=1
  ____________

  For the purpose of this Decision, a ‘personal music player’ means a
  portable device, that is not covered by Directive 1999/5/EC or
  Directive 2006/95/EC, with headphones or earphones, used to listen to
  recorded, generated or broadcasted sound.

  1. For the purpose of Article 4(1)(a) of Directive 2001/95/EC, the
  safety requirement for personal music players shall be the following:
  Personal music players shall be designed and manufactured in a manner
  that ensures that, under reasonably foreseeable conditions of use,
  they are inherently safe and do not cause hearing damage.

  2. The requirement set out in paragraph 1 shall include in particular
  the following:

  (1) Exposure to sound levels shall be time limited to avoid hearing
  damage. At 80 dB(A) exposure time shall be limited to 40 hours/week,
  whereas at 89 dB(A) exposure time shall be limited to 5 hours/week.
  For other exposure levels a linear intra- and extrapolation applies.
  Account shall be taken of the dynamic range of sound and the
  reasonably foreseeable use of the products.

  (2) Personal music players shall provide adequate warnings on the risks involved in using the device and to the ways of avoiding them and information to users in cases where exposure poses a risk of hearing damage.
  ____________

  Related documents:
  http://ec.europa.eu/health/opinions/en/hearing-loss-personal-music-player-mp3/
  http://europa.eu/rapid/press-release_IP-08-1492_en.htm
  http://ec.europa.eu/news/environment/090928_en.htm
  http://europa.eu/rapid/press-release_IP-09-1364_en.htm

  [Originally reported in private bug 1370591.]

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