According to the UK's Daily Mail, future versions of the iPod and iPhone may be engineered to automatically control volume, Macworld is reporting:

"The roots of this rumor stem from an Apple patent, one that would cause iPods and iPhones to calculate how long the device has been playing at a particular, potentially harmful, volume, and gradually reduce that volume to a safe level."

However, the current volume depends both on the music recording itself and the sensitivity of the ear buds used, not just the volume dial. Anyone familiar with the recording industry, or even any music enthusiast who has made a playlist, knows about the recent loudness wars that cause CDs from the past few years to be mastered at a much higher volume than CDs from the 1980's and early 1990's. So any attempt to say, for example, "60% or higher is dangerous" doesn't take that into account. Plus, different headsets have different sensitivity ratings, which cause certain models to be much louder (and more dangerous) at the same iPod volume dial level than others.

Anything to help raise awareness and prevent long-term hearing damage is a very good thing. Here's hoping that if Apple does add auto-limiting, it takes these issues into account.

Auto-volume may be a turn-off for some [Macworld]