Automated Noninvasive Motion Measurement of Auditory Organs in Fish Using Ultrasound

Abstract

A scanning underwater, ultrasonic system has been developed to measure the in vivo vibrational amplitude response of fish hearing organs to low-frequency sound. The fish is insonified with a 20-MHz source while stimulated in a single-frequency sound field. Spectral analysis of the echoes due to the acoustic impedance mismatches at the auditory organs provides the desired amplitude information. A computer-controlled scanning system allows nearly simultaneous measurements of the response of the various organs. The system is capable of measuring displacements of 12Å with a spatial resolution of 0.28 mm.

Sonoelasticity imaging: Theory and experimental verification

“…(1) the study of vibrating targets u•ing coherent radiation (laser, sonar, and ultrasound) (Holen et al, 1985;Cox and Rogers, 1987;Taylor, 1976Taylor, , 1981,…”

The vibrational response of single-chambered fish swimbladders to low-frequency sound

“…The frequency spectrum of the reflected ultrasound consists of the original transmitted frequency plus sidebands at the summed frequency and difference frequencies of the ultrasound and the low-frequency stimulus. The radial displacement of the swimbladder is calculated from the relative amplitude of the sidebands to the carrier (Cox and Rogers, 1987).…”

A continuous-wave ultrasound system for displacement amplitude and phase measurement

“…The NIVAMS has been used to measure the displacement amplitude as a function of frequency for the peripheral auditory organs in teleost fish ͑e.g., Cox andRogers, 1987͒, human andporcine lungs ͑Lewis et al, 1994;Martin et al, 2000͒, and corneas of enucleated bovine eye globes ͑Schroeder and Hastings, 1994͒. These data have been used to estimate resonant frequencies of structures under investigation ͑Martin et al, 2000͒, estimate corneal stiffness ͑Schroeder and Hastings, 1994͒, and to help identify the functional relationships between peripheral auditory organs in fish ͑Lewis et Cox and Rogers, 1987͒. Although the NIVAMS was able to measure displacement amplitudes of small structures with high resolution, in its original form the NIVAMS was unable to extract the displacement phase angle.…”

“…These data have been used to estimate resonant frequencies of structures under investigation ͑Martin et al, 2000͒, estimate corneal stiffness ͑Schroeder and Hastings, 1994͒, and to help identify the functional relationships between peripheral auditory organs in fish ͑Lewis et Cox and Rogers, 1987͒. Although the NIVAMS was able to measure displacement amplitudes of small structures with high resolution, in its original form the NIVAMS was unable to extract the displacement phase angle. Phase information is particularly important when attempting to identify resonant frequencies, estimate viscoelastic properties, and determine relationships between the motions of different structures.…”

“…Low-frequency shear waves are produced using an electromechanical shaker or audio speaker. Doppler ultrasound methods are used to measure vibration amplitudes in a region of interest and construct a gray-scale image to display vibration amplitudes ͑Taylor et al, 2000͒. Continuous-wave ultrasound has also been used to measure the motion of biological tissues undergoing acoustically induced vibrations ͑e.g., Cox and Rogers, 1987;Rogers and Hastings, 1989͒. The system developed by Rogers and Hastings ͑1989͒ has been referred to as the noninvasive vibration amplitude measurement system ͑NIVAMS͒.…”