# Tolerance of Natural Frequency & Resonance?

I'm writing a report at the moment about natural frequency, driving frequency and resonance - and I was wondering, is there a typical % tolerance inside which the driving frequency will cause resonance (or exhibit resonance-like characteristics)? Or does this tolerance depend with the material and construct involved?

An oscillator is usually characterized by its quality factor Q. This is a dimensionless parameter which measures how "good" of an oscillator it is. It also relates to the quantity you are interested in - a linear, damped oscillator will exhibit a lorentzian peaked response in the frequency domain. The bandwidth of the resonance (points where the response is decreased to 50%) is given by $\Delta f = \frac{f_0}{Q}$.