Sony IC RECORDER ICD-55 Mode D'emploi page 24

"Other Functions
Adjusting the Playback Speed
You can adjust the speed of the playback with the use of the PLAY SPEED
selector on the bottom.
To play back rapidly
Set PLAY SPEED to FAST.
"FAST" will flash three times in the display
window and the playback speed will
increase about 30%.
To play back slowly
Set PLAY SPEED to SLOW.
"SLOW" will flash three times in the display
window and the playback speed will
decrease about 15%.
To play messages with normal speed
Set PLAY SPEED to NORMAL.
24
GB
PLAY SPEED selector
PLAY SPEED
SLOW NORMAL FAST