Presentation on theme: "1 Non-Linearities Linear systems (e.g., filters) can change the intensity and phase of a signal input. Non-linear systems (e.g., amplfiers) not only can."— Presentation transcript:
1 Non-Linearities Linear systems (e.g., filters) can change the intensity and phase of a signal input. Non-linear systems (e.g., amplfiers) not only can modify the existing input, but can add sinusoids to the output. These additional signals are referred to as distortion.
8 Resonance General Principle of Resonance. When a periodically vibrating force is applied to an elastic system, the elastic system will be forced to vibrate initially at the frequency of the applied force. The nearer the frequency to the applied force to the natural (resonant) frequency of the elastic system, the greater will be the resulting amplitude of vibration.
9 Resonance The resonant frequency is directly related to the mass and stiffness reactance of the system. > mass, the lower the resonant frequency > stiffness, the greater the resonant frequency. Most vibrating objects have multiple resonant frequencies (e.g., harmonics).
10 Sharply and broadly tuned resonators Sharply tuned … Low rate of damping, more definitive tonal quality Broadly tuned … High rate of damping, poor tonality
11 Hemholtz Resonators Greater the volume the lower the resonant frequency Greater the neck diameter the higher the resonant frequency
12 Wavelenth Resonator Greater the length the lower the resonant frequency 1/2 wavelength resonator 1/4 wavelength resonator
13 Wavelength Resonator 1/2 wavelength resonators resonate at whole number multiples of the primary resonant frequency. …. e.g., 100, 200, 300, 400 Hz 1/4 wavelength resonators resonate at ODD multiples of the resonator frequency. … e.g., 100, 300, 500, 700 Hz
14 Resonator Applications Auditory system ear canal, tympanic membrane/ossicles, basilar membrane Amplification acoustic and electrical Tuning forks Vocal tract oral, nasal, and pharyngeal cavities. Other
15 Transfer Function Background: Need to understand sound system, which is anything that responds to sound. E.g., vocal tract, amplification, auditory system, filters, etc.
16 Transfer Function Transfer function reflects how the sound system changes the amplitude, frequency or phase of the signal. E.g., Transfer Function of Vocal Tract
17 Transfer Function Head Related Transfer Function