Introduction to Acoustics (Part 2)

Week 1. Radiation – Breathing & Trembling Sphere Problem

- What happens if we have a certain discontinuity that is a function of three spatial variables (e.g. x,y,z for Cartesian coordinate)?

- What are the radiation characteristics of a breathing sphere, which is assumed to vibrate omni-directionally with equal magnitude?

- What is the difference between a breathing sphere and a trembling sphere, which vibrates in a certain direction with a uniform velocity?

Week 2. Radiation – Baffled Piston & Finite Vibrating Plate Problem

- How can we generate sound? By the fluctuation of fluid particles or the vibration of structures? How are they related?

- How can we understand the radiation of a finite vibrating plate? Can we assume this plate as numerous vibrating pistons?

 Week 3. Scattering & Diffraction / Kirchhoff-Helmholtz Equation

- How can we express the wave propagation when it is reflected due to the presence of discontinuities in space?

- How can we explain the circumstances under which we can hear sound but cannot see the sound source?

- What is the relation between the wavelength and the diffraction?

Week 4. Wave Propagation in Space / Reverberation Period and its Design Application

- If there are different types of impedance distribution in space, how can we explain the propagation characteristics?

- How can we acoustically define ‘large’ or ‘small’ space’? Is it related to the frequency?

- Is there any measure that can represent the characteristics of the space?

Week 5. Wave Propagation in Space / Duct Acoustics

- How can we express the sound field that is neither fully diffuse field nor only a direct field?

- When the size of the space is small relative to wavelength, what happens to the propagation of sound?

- When the length of one direction is significantly greater than the cross-sectional direction of the space, how does the wave propagate with respect to its wavelength?

Yang-Hann Kim
Professor
Mechanical Engineering