2. Resonance Enhancement of the intensity of a particular frequency component(s) with respect to the intensity of the other components that occurs when its frequency equals or is close to the natural frequency of vibration of an object. Enhancement of the intensity of a particular frequency component(s) with respect to the intensity of the other components that occurs when its frequency equals or is close to the natural frequency of vibration of an object. Resonant frequency Resonant frequency Determined by characteristic impedance Determined by characteristic impedance

3. Filters Resonators that modify the frequency of vibrating objects. Resonators that modify the frequency of vibrating objects. Low pass filter: Passes frequencies below a cut-off frequency Low pass filter: Passes frequencies below a cut-off frequency High pass filter: Passes frequencies above a cut-off frequency High pass filter: Passes frequencies above a cut-off frequency Band pass: Passes frequencies between two cut-off frequencies (upper and lower cut-off) Band pass: Passes frequencies between two cut-off frequencies (upper and lower cut-off) Band reject: Rejects frequencies between two cut-off frequencies Band reject: Rejects frequencies between two cut-off frequencies

4. White noise White noise White noise LP filtered, 2000 Hz cut- off LP White noise HP filtered, 2000 Hz cut-off HP White noise BP filtered, 2000 Hz and 3000 Hz cut-offs BP White noise BR filtered, 2000 Hz and 3000 Hz cut-offs BR

5. Idealized filters and real filters

6. Cut-off frequency -6 dB/Octave Cut-off frequency/frequencies Roll-off rate or Attenuation rate (dB/Octave)