Technical Question: Volume Limit

Discussion in 'iPhone' started by coreybox, Dec 22, 2010.

  1. coreybox macrumors member

    Oct 28, 2005
    Is the volume limit (Settings->iPod->Volume Limit) setting a true limiter, or an attenuator?

    Meaning, does it actually control the power level (limit on actual volume, or decibels) sent to the headphones, and not allow ANYTHING over a set point, or does it simply lower the volume a set amount.

    If no one knows for certain, is there a convenient way to contact apple with this question?

  2. Small White Car macrumors G4

    Small White Car

    Aug 29, 2006
    Washington DC
    I don't know for certain, but I recall the reason for that feature is to assist parents who are worried about their children's ears.

    That's why it allows you to lock it with a password.

    So given all that I'm going to assume it acts as a hard cut-off point. That's the only way that makes sense given the way it was advertised.
  3. coreybox thread starter macrumors member

    Oct 28, 2005
    I agree, that is what I'd expect it to do.

    Playing around with it though, it definitely seems to be readjust the max point for the volume slider.

    If you have volume at max, and then lower the volume limit setting, the volume goes down. This is expected. The volume control still shows to be at max. Again, expected.

    If you then remove the volume limit (turn it off/max it out), the volume control no longer is at the max, but it now resides somewhere in the middle (presumably the place the volume limit was set).

    That seems to indicate that it just attenuates the signal, or doesn't let you turn the volume up as high.... it doesn't really limit the actual output. I was wondering if anyone knew for sure.

    A better experiment, which I'll try to perform later, would be to have two audio files with a noticeable difference in volume. Play the quiet one, and adjust the volume limit so that it reduces the volume for this file. Now when selecting the louder file, if it still appears louder then the volume limit is attenuating by a set amount, and not actually limiting the output level.
  4. MicroApple macrumors regular

    Jul 26, 2010
    Yeah just take 2 audio files and then crank one up to 200% and then add the volume control and see if they are the same or different.
  5. coreybox thread starter macrumors member

    Oct 28, 2005
    Just FYI, I did try the previously mentioned experiment.

    The two files still had an apparent volume jump. I think we can conclusively say that the volume limit feature just attenuates the max volume by a set amount.
  6. Arkku macrumors newbie


    Aug 13, 2010
    Helsinki, Finland
    Seems like an error-prone approach: in a noisy environment it would also hear external noise and turn down the phone's volume exactly when you would probably like to have it loud to hear at all. On the other hand, in an otherwise quiet environment the maximum output of a specific phone model at a certain volume is predictable, so the main advantage of your approach would be dynamically adapting to the audio source. However, for that to actually be useful, the volume should also go back up to the "normal" level after the loud song/video has stopped. Otherwise over time it will eventually reach the point where the loudest sound possible at that volume setting is below the threshold (i.e., you could just as well have used a constant reduction of volume), or the user has to manually keep turning it back up for the quiet songs.

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