The purpose of this ongoing research is to determine ambient noise levels, signal-to-noise ratios (SNRs), and RTs in daycare centers. To date, 248 measures of ambient noise levels have been obtained in occupied infant/toddler rooms of 11 daycare centers and 109 measures in 7 of the 11 daycares unoccupied. The mean occupied levels were 57 dBA and 66 dBC and the mean unoccupied levels were 38 dBA and 56 dBC. A 1/3 OB analysis revealed that the occupied levels were relatively constant (46–50 dB) from 63 to 2000 Hz while the unoccupied levels decreased as frequency increased especially after 125 Hz. Using several different speech spectrums compared with the occupied 1/3 OB levels, estimated SNRs ranged from −3 to 12 dB. Dosimeter measurements (N=932) revealed that the occupied daycares had an average peak sound level of 103 dB, high-threshold level of 62.5 dB, time-weighted average of 55.9 dB, and noise dose of 1.3%. Additional noise measurements and RTs are currently being collected. Overall, the unoccupied dBA levels and the estimated SNRs were less than recommended in the ASHA 1995 guidelines for classroom acoustics. [Work supported by PHS/NIH (1-R01-HD31540-01A2) Otitis Media, Behavior and Attention in Daycare.]
At the last ASA meeting, preliminary data was shared on the background noise in daycare centers. At this meeting, further research in the acoustical analysis of infant/toddler rooms in seven daycare centers will be discussed in relation to speech communication. Information concerning the collection and analysis of ambient noise, signal-to-noise ratios (SNRs), reverberation times (RT), and early decay time (EDT) will be shared. Comparisons will be made between the measurements and data collection techniques of ambient noise from dosimeters, sound level meters, and other long-term data acquisition techniques. Comparisons of the overall and octave band RTs and EDTs from each of the rooms in the study will be shown. Finally, the calculation of SNRs will be shown for both steady-state and dynamic signals. The steady-state SNR uses several different speech spectra compared to the occupied 1/3-octave band noise levels. The dynamic SNRs are calculated using microphones placed at both the caregiver and the infant or toddler. [Work supported by PHS/NIH (1-R01-HD31540-01A2) Otitis Media, Behavior and Attention in Daycare.]
Whistles were used to determine the presence of hydrogen and/or methane in mines before 1900 in Germany. Since early in the 20th century, the measurement of gas thermal conductivity using a hot wire technique has been the method of choice for nonspecific detection of ‘‘contaminating’’ gases in air. At that time, the choice of thermal conductivity detectors was motivated by the popularity of the Wheatstone Bridge circuit for precision measurement [P. E. Palmer and E. R. Weaver, ‘‘Thermal-conductivity method for the analysis of gases,’’ Tech. Papers of the Bureau of Standards, No. 249, Vol. 18, Jan. 7 (1924)]. At the present time, the precision-to-cost ratio for frequency/time measurements exceeds that for voltage/current measurement by more than an order of magnitude. This presentation will examine the advantages which an electronic measurement of sound speed using inexpensive components and novel resonator geometries can bring to the detection of gaseous contaminants in air. Prototype sensor/electronics results will be presented. A discussion of temperature compensation techniques as well as the sensitivity to changes in pressure and humidity will be included. [Work supported by ONR.]
Recent interest has developed within the environmental community in measuring the effective diffusion coefficient (De) of gases through soil. An electroacoustic system will be described that uses a plane-wave resonator and a phase-locked-loop automatic resonance frequency tracker. The gas analyzer is simple and can be built for about $100 from readily available plumbing parts and inexpensive transducers. A soil core is fitted into the top of a valved sample chamber and the resonator below is charged with a pure ‘‘tracer’’ gas (e.g., He, SF6), then the valve opened. The rate at which the tracer gas is replaced by air within the resonator is controlled by the soil’s De. The resonant frequency is maintained by a phase-locked-loop that compares the signal from an electret microphone with a square wave reference generated by the same monolithic function generator (XR 2206) that excited an electrodynamic loudspeaker with a sinusoidal current. The resonator temperature is monitored using a monolithic IC temperature sensor (AD 592) providing an output current of 1 μA/K. The mean molecular weight of the gas mixture in the resonator is directly determined in real-time from the ratio of the absolute temperature to the square of the fundamental acoustic resonance frequency. [Work supported by ONR.]
Over the last few years, research into heavy hard impacts from fitness activities has become an active field of investigation and product development. In order in facilitate our efforts, Pliteq has built a custom drop tower capable of repeatability dropping up to 150 kg from well over 2 m height. During the impact, the force, displacement, velocity, and acceleration can be obtained. This paper will give an overview of this apparatus, the type of data that it can collect, how this data can be used to make better products and how the data can be used to predict field performance.
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.