iPhone - AudioQueueLevelMeterState - What are the units for the power?

In iPhone's library, AudioQueue.h file has a structure AudioQueueLevelMeterState. It has two floats -> mAveragePower and mPeakPower What are the units st开发者_如何学运维ored in them. Is it decibels or not?

Since neither the documentation nor header comments say so I think it is assumed to be the only standard unit. As far as I know, the decibel is the only unit of power for sound.

There are other units for measuring sound but only the decibel measures power (in the scientific sense.)