In a class of embodiments, a method and apparatus for detecting freefall
of a disk device (thereby predicting that the disk device will likely
suffer imminent physical impact) and typically also preventing damage
that a disk drive of the device would otherwise suffer if and when a
predicted impact occurs. In some embodiments, a disk device includes a
freefall detection processor and a CPU. The freefall detection processor
is configured to monitor acceleration data to determine whether the disk
device is in freefall and to perform at least one other operation (e.g.,
decoding of MP3-encoded audio data to generate decoded audio data) while
the CPU performs at least one other task. Other embodiments pertain to a
portable device including a digital audio processing subsystem and an
accelerometer. The digital audio processing subsystem is configured to
monitor acceleration data to identify any rhythm associated with motion
of the portable device and to modify the playback of audio data in
response to any such identified rhythm.