Frequency response is a measure of the amplitude of an oscillation as a function of frequency.
Sharpness of resonance is defined by the Q factor, which is related to how quickly the energy of the oscillating system decays.
The determinants of the sharpness in resonance depends on the system involved. Lots of physical systems undergo resonance peaks, in the case of inhomogenously broadened optical oscillators (lasers) for example, the sharpness depends on the losses in the cavity, the gain medium, the shape and reflectivity of the mirrors and the length of the cavity.
Resonance peaks can be described mathematically using Gaussian, Lorentzian or a combination between the two (convolution) called a Voight profile. All these mathematicals functions have 2 important parameters, the maximum value and the Full width-Half maximum (The width of the curve at 1/2 the maximum value.) The ratio of these two parameters gives the Q values. Tall skinny peaks have a high Q, flat broad peaks have a low Q.
(Original post by joyie)
hello.. thanks for the answer about sharpness of the resonance, but as the thread started mentioned, could you please also explain what determines frequency reponse (what is it anyway?)