Data extrapolation method for near-field acoustic holography

A sparse equivalent source method for near-field acoustic holography.

This study examines a near-field acoustic holography method consisting of a sparse formulation of the equivalent source method, based on the compressive sensing (CS) framework. The method, denoted Compressive-Equivalent Source Method (C-ESM), encourages spatially sparse solutions (based on the superposition of few waves) that are accurate when the acoustic sources are spatially localized. The i...

Near-Field Acoustic Holography: The Frame Drum

A phase-sensitive setup for near-field acoustic holography was established in order to determine the characteristic resonance modes of a vibrating membrane. The experiment was carried out using a frame drum as the vibrating system of interest. By exciting the membrane at certain fundamental frequencies and recording the complex signals from the pressure and particle velocity fields across the d...

Near field acoustic holography with particle velocity transducers

Near-Field Acoustic Holography of a Vibrating Drum Head

This paper explains the design and construction of a phase-sensitive near-field acoustic holography apparatus. By using phase-sensitive lock-in amplifier techniques to record the complex signals of pressure and particle velocity microphones over an extended spatial region, small vibrations can be imaged using the acoustical properties of said vibrations. The apparatus is tested on a vibrating d...

Near field acoustic holography based on the equivalent source method and pressure-velocity transducers.

The advantage of using the normal component of the particle velocity rather than the sound pressure in the hologram plane as the input of conventional spatial Fourier transform based near field acoustic holography (NAH) and also as the input of the statistically optimized variant of NAH has recently been demonstrated. This paper examines whether there might be a similar advantage in using the p...