What is the underdamped frequency of an oscillation?

[Outrageous]

A mass is attached to a spring in underdamped oscillation, the damped frequency is ω^2=( ω1 )^2 -(∂/2m)^2
where ω is the damped angular frequency
ω1 is the natural angular frequency
∂ frictional coefficient
m is the mass attached to the spring

is the damped angular frequency is constant throughout the oscillations ( I mean the angular oscillation is constant until the oscillation stop)
I think the oscillation should not oscillate with constant angular damped frequency. but the formula of damped oscillation is not varies with time so is that constant??

thank you.

 

[Simon Bridge]

In the underdamped case the frquency does not change with time - this is correct. In all the other possibilities there are no oscillations at all.

http://en.wikipedia.org/wiki/Harmonic_oscillator#Damped_harmonic_oscillator

 

[Outrageous]

Thank you.