Doepfer

I have a question about white noise and random notes. In my own setup 
(most of it Doepfer, but not all) - I generate random notes by 
inputting the noise generator into the sample & hold module, and then 
getting my random frequency tones by inputting a trigger into the S&H 
from a clock. My query is - If the noise generator is actually 
outputting an audio noise signal rather than a rapidly changing train 
of voltages, how does the sample & hold recognise them ? - Surely the 
sample & hold circuit only recognises VOLTAGE LEVELS rather than 
frequencies.
If I can patch the noise generator straight into a mixer and hear 
noise, then surely that signal is not a train of voltages, but is a 
train of frequencies.
Does this mean that the sample & hold can be used as a pitch-to-voltage 
converter ?
.... or am I getting something wrong here ?
Richard