scholarly journals Spatiotemporal patterns of avian vocal activity in relation to urban and rural background noise

2017 ◽  
Vol 1 (1) ◽  
pp. 1-1 ◽  
Author(s):  
Katherine E. Gentry ◽  
David A. Luther
Keyword(s):  
Background Noise ◽  
Activity Patterns ◽  
Low Frequency ◽  
Rural Landscape ◽  
Signal Interference ◽  
Frequency Noise ◽  
Low Frequency Noise ◽  
Noise Levels ◽  
Frequency Bands ◽  
Vocal Activity

Background noise can interfere with and influence acoustic communication behavior. Signal interference is dependent on the amplitude and spectral characteristic of background noise, which varies over space and time. The likelihood of signal interference is greater when background noise is concentrated within the same frequency bands of an animal’s vocalization, but even a partial masking effect can elicit signaling behavior modification. Relative to a rural landscape, background noise in an urban landscape is disproportionately comprised by anthro- pogenic sound, which fluctuates in amplitude throughout the day and occurs primarily in low frequencies (0–2 kHz). In this study, we examined if urban-rural differences in vocal activity patterns exist in a species Zonotrichia leucophrys nuttalli that communicates above the frequency range of anthropogenic noise (2–8 kHz). We tested whether vocal activity patterns changed in relation to sound in the high or low frequency bands within and between urban and rural locations. Automated acoustic recording devices (ARDs) continuously recorded throughout the morning song chorus, 0500 to 1,100 h, during the 2014 breeding season in San Francisco (urban) and Marin (rural) Counties, CA. Supervised learning cluster analysis was used to quantify vocal activity by totaling the number of songs. In general, vocal activity was greater in urban locations com- pared to rural locations. However, within rural and urban study sites, we found vocal activity decreased where low frequency noise levels were higher. There was not a relationship between vocal activity and high frequency, biotic sound. In both urban and rural locations, low frequency noise levels increased through the morning, while vocal activity remained relatively consistent. Our results demonstrate how patterns of vocal activity can change with low frequency, abiotic noise, even when there is no direct spectral overlap with the acoustic signal.

Spectral Characteristics of Heart Rate Variability in Noise Exposure

2014 ◽  
Vol 1079-1080 ◽  
pp. 515-521
Author(s):  
Li Ho Tseng ◽  
Ching Chang Yang ◽  
Yuan Po Lee ◽  
Hong Zhun Wu ◽  
Chia Yi Chou
Keyword(s):  
Heart Rate ◽  
Heart Rate Variability ◽  
Spectral Analysis ◽  
Background Noise ◽  
Low Frequency ◽  
Cardiovascular Responses ◽  
Frequency Noise ◽  
Cardiovascular Activity ◽  
Low Frequency Noise ◽  
Noise Levels

Ecological studies have shown that the chronic effects of exposure to environmental noise cause annoyance. However, in the past, most studies have used questionnaires to evaluate the effects of noise pollution on psychosomatic responses. This study investigated cardiovascular activity changes in exposure to low-frequency noise at various noise intensities. The authors hypothesized that distinct noise intensities affect cardiovascular activity, which would be reflected in the spectral analysis parameters. The evaluation intensities of low frequency noises (from 20 to 200 Hz) were background noise (BN), 70-dBC, 80-dBC, and 90-dBC. The electrocardiographic (ECG) data was recorded for 5 minutes under various noise levels. The cardiovascular responses were evaluated using spectral analysis of the beat-to-beat (RR) intervals obtained from ECG signals. The results showed that the average blood pressure and mean RR interval variability did not substantially change relative to the noise levels. However, the low-frequency (LF) power and the ratio of LF power to high-frequency power (LF/HF) from ECG under the BN condition were significantly lower than the 80-dBC, and 90-dBC noise levels. In addition, the normalized LF of the background noise condition was significantly lower than the low-frequency of the noise levels at various intensities. In conclusion, the frequency-domain-based measures appear to be a powerful tool for exposure to low-frequency noise, even in short-term heart rate variability time series.

Recurrence Plot Analysis of HRV for Exposure to Low-Frequency Noise

2014 ◽  
Vol 1044-1045 ◽  
pp. 1251-1257 ◽  
Author(s):  
Shih Tsung Chen ◽  
Chia Yi Chou ◽  
Li Ho Tseng
Keyword(s):  
Low Frequency ◽  
Cardiovascular Responses ◽  
Recurrence Plot ◽  
Frequency Noise ◽  
Cardiovascular Activity ◽  
Low Frequency Noise ◽  
Noise Levels ◽  
Noise Condition ◽  
Plot Analysis ◽  
Recurrence Plot Analysis

Previous studies have indicated that the chronic effects of exposure to low-frequency noise causes annoyance. However, during the past two decades, most studies have employed questionnaires to characterize the effects of noise on psychosomatic responses. This study investigated cardiovascular activity changes in exposure to low-frequency noise for various noise intensities by using recurrence plot analysis of heart rate variability (HRV) estimation. The authors hypothesized that distinct noise intensities affect cardiovascular activity, which would be reflected in the HRV and recurrence quantification analysis (RQA) parameters. The test intensities of noises were no noise, 70-dBC, 80-dBC, and 90-dBC. Each noise level was sustained for 5 min, and the electrocardiogram (ECG) was recorded simultaneously. The cardiovascular responses were evaluated using RQA of the beat-to-beat (RR) intervals obtained from ECG signals. The results showed that the mean RR interval variability and mean blood pressure did not substantially change relative to the noise levels. However, the length of the longest diagonal line (Lmax) of the RQA of the background noise (no noise) condition was significantly lower than the 70-dBC, 80-dBC, and 90-dBC noise levels. The laminarity showed significant changes in the noise levels of various intensities. In conclusion, the RQA-based measures appear to be an effective tool for exposure to low-frequency noise, even in short-term HRV time series.

scholarly journals Single JFET Front-End Amplifier for Low Frequency Noise Measurements with Cross Correlation-Based Gain Calibration

Electronics ◽  
2019 ◽  
Vol 8 (10) ◽  
pp. 1197
Author(s):  
Graziella Scandurra ◽  
Gino Giusi ◽  
Carmine Ciofi
Keyword(s):  
Background Noise ◽  
Cross Correlation ◽  
Low Frequency ◽  
Open Loop ◽  
Low Noise ◽  
Frequency Noise ◽  
Low Frequency Noise ◽  
Front End ◽  
Voltage Amplifier ◽  
Noise Measurements

We propose an open loop voltage amplifier topology based on a single JFET front-end for the realization of very low noise voltage amplifiers to be used in the field of low frequency noise measurements. With respect to amplifiers based on differential input stages, a single transistor stage has, among others, the advantage of a lower background noise. Unfortunately, an open loop approach, while simplifying the realization, has the disadvantage that because of the dispersions in the characteristics of the active device, it cannot ensure that a well-defined gain be obtained by design. To address this issue, we propose to add two simple operational amplifier-based auxiliary amplifiers with known gain as part of the measurement chain and employ cross correlation for the calibration of the gain of the main amplifier. With proper data elaboration, gain calibration and actual measurements can be carried out at the same time. By using the approach we propose, we have been able to design a low noise amplifier relying on a simplified hardware and with background noise as low as 6 nV/√Hz at 200 mHz, 1.7 nV/√Hz at 1 Hz, 0.7 nV/√Hz at 10 Hz, and less than 0.6 nV/√Hz at frequencies above 100 Hz.

Annoyance Due to Environmental Low Frequency Noise and Source Location — A Case Study

1989 ◽  
Vol 8 (2) ◽  
pp. 30-39 ◽  
Author(s):  
R.N. Vasudevan ◽  
H.G. Leventhall
Keyword(s):  
Field Study ◽  
Microphone Array ◽  
Low Frequency ◽  
Source Location ◽  
Frequency Noise ◽  
Low Frequency Noise ◽  
Noise Levels ◽  
Industrial Source

This case study shows that objective criteria usually based solely on the dB(A) scale are not adequate in evaluating the annoyance due to low frequency noise. Levels which are often low enough to discount the likelihood of a noise nuisance, however, were found to be subjectively annoying. The field study reported here demonstrates that the complainant's annoyance response was due more to the unpleasant nature of the low frequency noise than to its actual level. Positive location of a distant industrial source with the aid of a specially designed three element microphone array provided much needed relief to the complainant.

DEDICATED INSTRUMENTATION FOR HIGH SENSITIVITY, LOW FREQUENCY NOISE MEASUREMENT SYSTEMS

2004 ◽  
Vol 04 (02) ◽  
pp. L385-L402 ◽  
Author(s):  
C. CIOFI ◽  
G. GIUSI ◽  
G. SCANDURRA ◽  
B. NERI
Keyword(s):  
Background Noise ◽  
Flicker Noise ◽  
Low Frequency ◽  
High Sensitivity ◽  
Design Guidelines ◽  
Low Noise ◽  
Frequency Noise ◽  
Low Frequency Noise ◽  
Low Frequencies ◽  
Noise Measurements

Low Frequency Noise Measurements (LFNM) can be used as very sensitive tool for the characterization of the quality and the reliability of electron devices. However, especially in those cases in which the frequency range of interest extends below 1 Hz, instrumentation with an acceptable low level of background noise is not easily found on the market. In fact, at very low frequencies, the flicker noise introduced by the electronic components which make up the instrumentation becomes predominant and several interesting phenomena which could be detected by means of LFNM may result completely hidden in the background noise. This consideration is not limited to the case of input preamplifiers but does extend to any piece of instrumentation that contributes to the LFNM systems, and in particular to the power supplies used for biasing the Device Under Test. During the last few years, our research groups have been strongly involved in the design of very low noise instrumentation for application in the field of LFNM. In this work we report the main results which we have obtained together with a discussion of the design guidelines that have allowed us, in a few cases, to reach noise levels not to be equalled by any instrumentation available on the market.

GEOMETRY AND BIAS DEPENDENCE OF LOW-FREQUENCY RANDOM TELEGRAPH SIGNAL AND 1/f NOISE LEVELS IN MOSFETS

2005 ◽  
Vol 05 (04) ◽  
pp. L539-L548 ◽  
Author(s):  
MASATO TOITA ◽  
LODE K. J. VANDAMME ◽  
SHIGETOSHI SUGAWA ◽  
AKINOBU TERAMOTO ◽  
TADAHIRO OHMI
Keyword(s):  
Low Frequency ◽  
Frequency Noise ◽  
Gate Bias ◽  
Low Frequency Noise ◽  
Noise Levels ◽  
Temperature Plasma ◽  
Random Telegraph Signal ◽  
Carrier Traps ◽  
Inherent Nature ◽  
Bias Condition

Low-frequency noise in MOSFETs is considered to originate from two distinctive sources: Random Telegraph Signal caused by carrier traps at the border of the SiO 2/ Si interface and 1/f fluctuation due to inherent nature of lattice scattering in a Si crystal. It is very important to distinguish these two mechanisms. Relative amplitude of RTS and 1/f noise depends on the number of carriers under the gate electrode, which makes it channel size as well as gate-bias dependent. In this paper, we discuss the dependence of the amplitudes of RTS and 1/f noise in MOSFETs on sample geometry and gate bias condition. We discuss low-frequency noise reduction by utilizing low electron-temperature plasma for gate oxidation as well.

Long term estimations of low frequency noise levels over water from an off-shore wind farm

2014 ◽  
Vol 135 (3) ◽  
pp. 1106-1114 ◽  
Author(s):  
Karl Bolin ◽  
Martin Almgren ◽  
Esbjörn Ohlsson ◽  
Ilkka Karasalo
Keyword(s):  
Wind Farm ◽  
Low Frequency ◽  
Frequency Noise ◽  
Low Frequency Noise ◽  
Noise Levels
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