How poles and zeros affect the frequency response?

Poles and zeros significantly influence a system's frequency response. Poles, which are values in the denominator of a transfer function, tend to create resonances or peaks in the response and can lead to increased gain in certain frequency ranges, often causing attenuation at others. Zeros, located in the numerator, can cancel out the effects of poles, resulting in a reduction of gain at specific frequencies and contributing to the overall shape of the response. Together, the placement of poles and zeros determines the stability, bandwidth, and filtering characteristics of the system.