Pitch phenomena related to the periodic interruption rate of white noise have traditionally been regarded as evidence for time domain pitch processing in the auditory system since spectra of these signals are flat. Short-term spectra, however, contain information about the interruption rate. Melodic interval identification experiments were performed with sounds comprising low-pass filtered noise modulated by either a sine wave, a square wave, or a periodic narrow pulse wave. Melodic intervals were generated by varying the modulation frequency fm while the low-pass cutoff frequency fco of the noise was an experimental variable. The correct identification score shows a particular dependence on the ratio fco/fm for each type of modulation signal. Shapes and relative positions of performance functions are compared with predictions derived from an energy detector (time domain) model and a short-term power spectrum correlation (frequency domain) model, and are found to support the former more strongly than the latter. There is some evidence, however, for the existence of both types of processing in the auditory system.
Cepstral Analysis is an example of nonlinear filtering that has been applied to extracting the properties of transmission path and source characteristics in acoustics. To see why this is so, we review some of the properties of linear windowing in the time and frequency domains with a view to revealing the limitations that these methods have. We then describe the cepstrum and the conditions under which it can be helpful in separating source and path characteristics. The method is illustrated by describing some applications. Finally, research directions that may help to extend the applicability of cepstral analysis to structural vibration transmission are discussed.
The peak in sound transmission through a single isotropic panel at the critical frequency causes a drop in transmission loss (TL) of that panel and of composite walls constructed with such a panel as face sheets. In investigations on a composite wall with plywood face sheets and styrofoam core, such a coincidence dip was not observed. The aim of this study is to investigate the disappearance of coincidence notch and the probable causes for such phenomena. The bending stiffness of a single ply of plywood changes gradually from the softest direction to the stiffest direction. Therefore, the bending wave phase velocity and sound transmissibility change with direction. It is hypothesized that for a group of sound waves randomly incident on the panel, this change in transmissibility eliminates or lowers the peak and, therefore, the coincidence notch smoothens. A plywood panel consists of plies laminated with their grains in different directions. These laminations of the plies may reduce orthotropy in thick plywood panels. A comparison of theoretically predicted and experimentally observed TL of plywood sheets supports the hypothesis that anisotropy is the reason for a lack of coincidence transmission for some plywood sheets.
sensorresponds twice as much to radial strain as to axial strain. For a fiber optic-or polymeric-type hydrophone, the strain sensor could be wound helically at 54.7 ø from the axial direction to obtain a truevolume response. Other winding methods will achieve similar acoustic results, but they will reduce the ability of the sensor to bend. Sensitivity of several designs will be discussed. 8:45 SS2. Design of rubber mandrel fiber optic hydrophones.
The peak in sound transmission through a single isotropic panel at the critical frequency causes a drop in transmission loss (TL) of that panel and of composite walls constructed with such a panel as a face sheet. In investigations on a composite wall with plywood face sheets and Styrofoam core, such a coincidence dip was not observed. The aim of this study is to investigate the disappearance of coincidence notch and the probable causes for such a phenomena. The bending stiffness of a single ply of plywood changes gradually from the softest direction to the stiffest direction. Therefore, the bending wave phase velocity and sound transmissibility change with direction. It is hypothesized that for a group of sound waves randomly incident on the panel, this change in transmissibility eliminates or lowers the peak and, therefore, the coincidence notch smoothens. A plywood panel consists of plies laminated with their grains in different directions. These laminations of the plys may reduce orthotropy in thick plywood panels. A comparison of theoretically predicted and experimentally observed TL of plywood sheets supports the hypothesis that antisotropy is the reason for a lack of coincidence transmission for some plywood sheets.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.