title: A novel technique to measure the group velocity of sound in dispersive media.
abstract: A technique is proposed for measuring the group velocity of sound by a frequency-modulated (FM) continuous wave (CW) technique. Detailed calculations are presented, showing that V(g)=(deltaomega(m)/deltaphi)d , where V(g), deltaomega(m), deltaphi, and d are, respectively, the group velocity, change of modulation frequency, phase change of the received signal detected by a biphase lock-in amplifier, and the distance traveled by the sound. The approach has the advantage of high resolution compared to the conventional time-of-flight measurement technique.
authors.affiliation: Dept. of Phys. and Astron., Northwestern Univ., Evanston, IL.
authors.forename: Z
authors.initials: Z
authors.lastname: Zhao
authors.forename: S D
authors.initials: SD
authors.lastname: Adenwalla
authors.forename: J B
authors.initials: JB
authors.lastname: Ketterson
authors.forename: B K
authors.initials: BK
authors.lastname: Sarma