Tactile VU Meter
From: Spare Time Gizmos

Blind individuals are frequently employed in the radio broadcasting or
recording fields, and even those who are not often want to use a tape
recorder as part of a home stereo system. Unfortunately conventional VU
meters, both analog and digital, are completely inaccessible to those without
sight. There have been attempts to make accessible VU meters using various
audible indicators, but in a recording environment audible indicators have
never been practical. 

Read the entire article at:
http://www.sparetimegizmos.com/Hardware/Tactile_VU_Meter.htm

Schematic:
http://www.sparetimegizmos.com/Downloads/VU_Meter.zip