[UKönig]

Here is some technical information about the type VIIC (sound profiles) from U-boat archive.net, enjoy!

Page 24
A. Ship Information
U-Boat Type VIIC

24
I. General
U-boat Information

h) Sound levels (from testing with "U-45 and "U-51")
(updated for VII C boats after testing)

Boat lying on the bottom
Sound from auxiliary machinery at 250 meters distance
Operating: Underwater telegraphy converter and gyro compass

Not heard
Gyro compass-circulation pump
Gyro compass- converter
Extending attack periscope
Extending air search periscope
Tracking motor in torpedo data computer
Dive planes electric drive
Dive planes (hand drive)
Main rudder electric drive
Quiet
Radio converter
Hydraulic oil pump
W.C. pump
Echolot (shallow depth device)
Control valves for the periscope drive
Engine order telegraph without buzzer
Main rudder (hand drive)
Moderately loud
UT converter
Auxiliary LO pump
Retracting attack periscope
Retracting air search periscope
Compartment ventilation fan
Engine order telegraph with buzzer
Loud
Main drain pump
Walking in the boat
Very loud
Auxiliary drain and trim pump
Air compressor
Drive motor for turning attack periscope
Speaking in the boat
Working in the boat
Echolot (deep depth device)

Boat hanging on the periscope

Sound from auxiliary machinery at 250 meters distance. Motors stopped. No auxiliary machinery except for UT converter and gyro compass.

Not heard
Extending air search periscope
Extending attack periscope
Moderately loud
Retracting air search periscope
Retracting attack periscope

Boat at attack depth
Boat driven at attack depth in a circle of 500 meters radius
Not heard
One motor KF = 50 RPM
Attack periscope
Dive plane driving motor
Both motors KF = 50 RPM
Compartment ventilating fan
Both dive plane driving motors
Quiet
Draining and trimming with air
Operating both dive planes by hand
Both motors 80 RPM
Loud
Draining and trimming with auxiliary drain and trim pump
Both motors 140 RPM
Both motors 120 RPM
Both motors LF 100 RPM
Very loud
Both motors 250 RPM
Both motors 200 RPM
Both motors 180 RPM
Both motors 160 RPM
At starboard 110 and port 90 RPM the noise is weaker than with both motors at 100 RPM
Draining and trimming by means of air at 80 RPM or less: slight noise is audible.
Detection range with different RPM rates (submerged)
At 80 RPM: 4500 meters (Detection range particularly large because of howling sound)
At 160 RPM: 5000 meters (Detection range lowered.)

From the U-boat owner's manual, about as official as it gets...