Interface transduction in the ZnO-SiO[sub 2]-Si surface acoustic wave device configuration
M. R. Melloch, R. L. Gunshor, C. L. Liu, and R. F. Pierret
Results are presented describing the operational behavior of a ZnO-SiO-Si surface acoustic wave (SAW) device with a new transducer configuration. In the new configuration the transducer is positioned at the ZnO-SiO interface; a metal overlays the transducer at the outer ZnO surface. The transduction ... [Appl. Phys. Lett. 37, 147 (2008)] published Tue Jul 22, 2008.
Apparatus for the continuous measurement of changes in ultrasonic velocity
A. M. Simpson, W. A. Roger, and M. H. Jericho
In measuring the velocity of sound in materials with plate-like of fibrous geometries, in thin foils, or in materials with high attenuation, the only clear signal is often after a single transit through the sample. A system is described which allows continuous measurements of changes of acoustic pro ... [Rev. Sci. Instrum. 51, 792 (2008)] published Tue Jul 22, 2008.
Device for improving ultrasonic transit time measurements with standard pulse echo equipment
Georg A. Reider and Erwin Kittinger
A simple and inexpensive device is described which in conjunction with conventional pulse echo equipment allows the direct measurement of the time interval between the zeros of selected individual cycles in different echoes with an accuracy better than 0.2 ns. ... [Rev. Sci. Instrum. 51, 355 (2008)] published Tue Jul 22, 2008.
Quantifying the through-thickness asymmetry of sound absorbing porous materials
Y. Salissou and R. Panneton
A method to quantify the through-thickness asymmetry of a sound absorbing porous material is proposed and discussed. Its calculation only requires impedance tube measurements of the acoustical surface impedance performed on both sides of the tested material. The method may be used for quality contro ... [J. Acoust. Soc. Am. 124, EL28 (2008)] published Fri Jul 18, 2008.
Dispersion relation for air via Kramers-Kronig analysis
Fernando J. Alvarez and Roman Kuc
A general expression for the dispersion of acoustic waves in air is obtained by combining the attenuation coefficient given by the ISO:9613-1 standard and the twice-subtracted Kramers-Kronig relation. Good agreement is found with published data of sound velocity at different frequencies and relative ... [J. Acoust. Soc. Am. 124, EL57 (2008)] published Fri Jul 18, 2008.
Laboratory studies of near-grazing impulsive sound propagating over rough water
Qin Qin, Sergei Lukaschuk, and Keith Attenborough
Acoustic impulses due to an electrical spark source (main acoustic energy near 15 kHz) have been measured after propagating near to the water surface in a shallow container resting on a vibrating platform. Control of the platform vibration enabled control of water wave amplitudes. Analysis of the r ... [J. Acoust. Soc. Am. 124, EL40 (2008)] published Fri Jul 18, 2008.
Particle filtering for dispersion curve tracking in ocean acoustics
Ivan Zorych and Zoi-Heleni Michalopoulou
A particle filtering method is developed for dispersion curve extraction from spectrograms of broadband acoustic signals propagating in underwater media. The goal is to obtain accurate representation of modal dispersion which can be employed for source localization and geoacoustic inversion. Results ... [J. Acoust. Soc. Am. 124, EL45 (2008)] published Fri Jul 18, 2008.
Effects of modulation wave shape on modulation frequency discrimination with electrical hearing
David M. Landsberger
Amplitude modulations of pulsitile stimulation can be used to convey pitch information to cochlear implant users. One variable in designing cochlear implant speech processors is the choice of modulation waveform used to convey pitch information. Modulation frequency discrimination thresholds were me ... [J. Acoust. Soc. Am. 124, EL21 (2008)] published Fri Jul 18, 2008.
Low-frequency Fourier analysis of speech rhythm
Sam Tilsen and Keith Johnson
A method for studying speech rhythm is presented, using Fourier analysis of the amplitude envelope of bandpass-filtered speech. Rather than quantifying rhythm with time-domain measurements of interval durations, a frequency-domain representation is usedthe rhythm spectrum. This paper describes the m ... [J. Acoust. Soc. Am. 124, EL34 (2008)] published Fri Jul 18, 2008.
Adaptive echolocation sounds of insectivorous bats, Pipistrellus abramus, during foraging flights in the field
Shizuko Hiryu, Tomotaka Hagino, Emyo Fujioka, Hiroshi Riquimaroux, and Yoshiaki Watanabe
Echolocation pulses emitted by wild Pipistrellus abramus were investigated while foraging for insects in the field. Similar to other European pipistrelles, the frequency structure during foraging varied. During the search phase, the bats emitted long shallow frequency-modulated pulses 911 ms in dur ... [J. Acoust. Soc. Am. 124, EL51 (2008)] published Fri Jul 18, 2008.
Harbor porpoise clicks do not have conditionally minimum time bandwidth product
Kristian Beedholm
The hypothesis that odontocete clicks have minimal time frequency product given their delay and center frequency values is tested by using an in-phase averaged porpoise click compared with a pure tone weighted with the same envelope. These signals have the same delay and the same center frequency va ... [J. Acoust. Soc. Am. 124, EL15 (2008)] published Fri Jul 18, 2008.