scholarly journals Acoustic Properties of Two Urban Song Dialects in the Orange-Tufted Sunbird (Nectarinia Osea)

The Auk ◽  
2005 ◽  
Vol 122 (1) ◽  
pp. 231-245 ◽  
Author(s):  
Noam Leader ◽  
Jonathan Wright ◽  
Yoram Yom-Yov
Keyword(s):  
Ambient Noise ◽  
Low Frequency ◽  
Acoustic Properties ◽  
Habitat Modification ◽  
Frequency Noise ◽  
Maximum Frequency ◽  
Atmospheric Conditions ◽  
Anthropogenic Habitat ◽  
Song Dialects ◽  
Song Types

AbstractBiologically important acoustic signals must be transmitted from a signaler to a receiver. Over distance, however, sounds may undergo modification through attenuation, degradation, and masking. Recent anthropogenic habitat modification occurring in many places—in urban habitats, in particular—has rapidly changed local topography and atmospheric conditions and generated new patterns of noise that are likely to interfere with communicative signals. As part of a study of microgeographic song dialects in an urban population of Orange-tufted Sunbirds (Nectarinia osea) in Israel, we examined the environmental influences on song transmission and reception in a rapidly developing human-altered environment. We examined the physical properties of the two dialect song types, which exhibit a large difference of 2–3 kHz in the maximum frequency of the trill, using sound transmission measurements to test how both song types propagate through a highly obstructed habitat of buildings and vegetation. Additionally, we examined how ambient noise—in particular, low-frequency noise arising mainly from automobile traffic—affects the transmission of both dialect songs. Finally, using song playback, we investigated the consequences of sound degradation on dialect recognition and discrimination by sunbirds. The dialect containing higher frequencies in the trill was found to undergo severe frequency-dependent attenuation, in which the maximum frequency of the trill notes drops by >2 kHz over a distance of 70–100 m (less than two territories away). Also, the possibility that the use of higher frequencies in that dialect group's song is intended to overcome masking by urban ambient noise, which is concentrated mainly in lower frequencies, was not supported by our findings. Males singing the high dialect responded differently to playbacks of an intact and an attenuated form of their dialect song. Taken together, our results suggest that the dialect containing higher frequencies in the trill may be unsuitable for effective long-range transmission through this particular sunbird habitat.Propiedades Acústicas de Dos Dialectos del Canto Urbano de Nectarinia osea

scholarly journals Detection of infrasound by the Atlantic cod

1986 ◽  
Vol 125 (1) ◽  
pp. 197-204 ◽  
Author(s):  
O. Sand ◽  
H. E. Karlsen
Keyword(s):  
Ambient Noise ◽  
Atlantic Cod ◽  
Low Frequency ◽  
Directional Pattern ◽  
Frequency Noise ◽  
Threshold Values ◽  
Sensory Inputs ◽  
A Value ◽  
Cardiac Conditioning ◽  
Lower Frequencies

Below about 50 kHz the level of ambient noise in the sea increases continuously towards lower frequencies. In the infrasound range the spectral slope is particularly steep. This low-frequency noise may propagate long distances with little attenuation, causing a directional pattern of infrasound in the sea. Using a standing-wave acoustic tube, we have studied the sensitivity of cod to infrasound down to 0.1 Hz by means of the cardiac conditioning technique. The threshold values, measured as particle acceleration, showed a steady decline towards lower frequencies below 10 Hz, reaching a value close to 10(−5)ms-2 at 0.1 Hz. The spectrum level at 0.1 Hz in the sea ranges between 120 and 180 dB (re 1 microPa), with corresponding particle accelerations from less than 10(−6) to more than 10(−4)ms-2. The sensitivity of cod is thus sufficient to detect the highest levels of ambient infrasound, and we put forward the hypothesis that fish may utilize information about the infrasound pattern in the sea for orientation during migration, probably in addition to an array of other sensory inputs.

Effects of Noise Frequency on Performance and Annoyance for Women and Men

1981 ◽  
Vol 52 (2) ◽  
pp. 435-441 ◽  
Author(s):  
Kelli F. Key ◽  
M. Carr Payne
Keyword(s):  
Sex Differences ◽  
Magnitude Estimation ◽  
High Frequency ◽  
Ambient Noise ◽  
Direct Relationship ◽  
Low Frequency ◽  
Frequency Noise ◽  
Complex Task ◽  
High Frequency Noise ◽  
Noise Frequency

Effects of noise frequencies on both performance on a complex psychomotor task and annoyance were investigated for men ( n = 30) and women ( n = 30). Each subject performed a complex psychomotor task for 50 min. in the presence of low frequency noise, high frequency noise, or ambient noise. Women and men learned the task at different rates. Little effect of noise was shown. Annoyance ratings were subsequently obtained from each subject for noises of various frequencies by the method of magnitude estimation. High frequency noises were more annoying than low frequency noises regardless of sex and immediate prior exposure to noise. Sex differences in annoyance did not occur. No direct relationship between learning to perform a complex task while exposed to noise and annoyance by that noise was demonstrated.

Blade-Wake Interaction Noise for Turbines With Downwind Rotors

2003 ◽  
Vol 125 (4) ◽  
pp. 497-505 ◽  
Author(s):  
G. M. McNerney ◽  
C. P. van Dam ◽  
D. T. Yen-Nakafuji
Keyword(s):  
Wind Turbine ◽  
Wind Turbines ◽  
Incidence Angle ◽  
Dynamic Pressure ◽  
Low Frequency ◽  
Frequency Noise ◽  
Atmospheric Conditions ◽  
Noise Mitigation ◽  
Local Flow ◽  
Wake Interaction

The interaction between the rotor and the tower wake is an important source of noise for wind turbines with downwind rotors. The tower wake modifies the dynamic pressure and the local flow incidence angle as seen by the blades and, hence, modifies the aerodynamic loading of the blade during blade passage. The resulting n per revolution fluctuation in the blade loading (where n is the number of blades) is the source of low frequency but potentially high amplitude sound levels. The Wind Turbine Company (WTC) Proof of Concept 250 kW (POC) wind turbine has been observed by field personnel to produce low-frequency emissions at the National Wind Technology Center (NWTC) site during specific atmospheric conditions. Consequently, WTC is conducting a three-phase program to characterize the low frequency emissions of its two-bladed wind turbines and to develop noise mitigation techniques if needed. This paper summarizes the first phase of this program including recent low-frequency noise measurements conducted on the WTC POC250 kW wind turbine, a review of the wake characteristics of circular towers as they pertain to the blade-wake interaction problem, and techniques to attenuate the sound pressure levels caused by the blade-wake interaction.

Theoretical End Experimental Evaluation of Perforations Effect on Sound Insulation

2017 ◽  
Author(s):  
Olga Khrystoslavenko ◽  
Raimondas Grubliauskas
Keyword(s):  
Noise Reduction ◽  
High Frequency ◽  
Sound Absorption ◽  
Low Frequency ◽  
Experimental Methods ◽  
Glass Wool ◽  
Acoustic Properties ◽  
Sound Insulation ◽  
Frequency Noise ◽  
Sound Reduction

To design a sound-absorbing panel, it is important to identify factors that affect the maximum sound absorption of low, middle and high frequency sounds. Perforation effect is very important for the noise-reducing and noiseabsorbing panels. Perforations are often used for sound reduction. Experimental data shows that the perforation is very effective to absorb low-frequency noise. In the presented study, influence of perforation coefficient of noise reduction was analyzed with theoretical and experimental methods. The experiments were conducted in noise reduction chamber using an perforated construction with glass wool filler. Sound reductions index of 15 dB indicates good acoustic properties of the panel.

scholarly journals Investigations on Low Frequency Noises of On-Shore Wind Turbines

Acoustics ◽  
2020 ◽  
Vol 2 (2) ◽  
pp. 343-367
Author(s):  
Esther Blumendeller ◽  
Ivo Kimmig ◽  
Gerhard Huber ◽  
Philipp Rettler ◽  
Po Wen Cheng
Keyword(s):  
Wind Turbines ◽  
Wind Farm ◽  
Residential Buildings ◽  
Measurement Data ◽  
Low Frequency ◽  
National Standards ◽  
Future Research ◽  
Frequency Noise ◽  
Atmospheric Conditions ◽  
Social Tasks

The expansion of renewable energy usage is one of the major social tasks in Europe and therefore requires acceptance and support from the population. In the case of onshore wind turbines, the complaints of local residents are often interpreted as infrasound disturbances conceivably caused by wind turbine operation. To improve the acceptance for wind energy projects, national standards and regulations need to incorporate such low frequency effects. This contribution presents long-term acoustic measurement data of low frequency noise recorded directly near wind turbines (emission) and inside of residential buildings (immission) with the objectives to identify the signal characteristics and main influential parameters. Different locations (wind farm and individual turbine), wind conditions, and time ranges are evaluated. It is shown that various frequency content below 150 Hz (harmonics of blade passing frequency, etc.) is connected to the rotation of the rotor blade and the operation of the generator. Furthermore, stable atmospheric conditions are determined to be of high importance for the transmission of the characteristic signals. For future research, this work also serves as an example for low frequency sound pressure data during operation and shutdown of wind turbines.

scholarly journals Ambient noise from ocean surf drives frequency shifts in non-passerine bird song

2020 ◽  
Author(s):  
Matteo Sebastianelli ◽  
Daniel T. Blumstein ◽  
Alexander N. G. Kirschel
Keyword(s):  
Background Noise ◽  
Ambient Noise ◽  
Selective Pressure ◽  
Low Frequency ◽  
Vocal Learning ◽  
Passerine Bird ◽  
Anthropogenic Noise ◽  
Masking Effect ◽  
Frequency Noise ◽  
Natural Noise

AbstractEffective communication in birds is often hampered by background noise, with many recent studies focusing on the effect of anthropogenic noise on passerine bird song. Continuous low-frequency natural noise is predicted to drive changes in both frequency and temporal patterning of bird vocalizations, but the extent to which these effects may also affect birds that lack vocal learning is not yet fully understood. Here we use a gradient of exposure to natural low-frequency noise to assess whether it exerts selective pressure on vocalizations in a species whose songs are innate. We tested whether three species of Pogoniulus tinkerbirds adapt their song when exposed to a source of continuous low-frequency noise from ocean surf. We show that dominant frequency increases the closer birds are to the coast in all the three species, and in line with higher noise levels, indicating that ocean surf sound may apply a selective pressure on tinkerbird songs. As a consequence, tinkerbirds adapt their songs with an increase in frequency to avoid the masking effect due to overlapping frequencies with ambient noise, therefore improving long-range communication with intended receivers. Our study provides for the first time, compelling evidence that natural ambient noise affects vocalizations in birds whose songs are developed innately. We believe that our results can also be extrapolated in the context of anthropogenic noise pollution, hence providing a baseline for the study of the effects of low-frequency ambient noise on birds that lack vocal learning.Significance StatementBirdsong is constantly under selection as it mediates key interactions such as mate attraction, competition with same-sex individuals for reproduction and competition with heterospecifics for space-related resources. Any phenomenon that interferes with communication can therefore have a profound impact on individual fitness. Passerines are more likely to avoid the masking effect of background noise because of their higher vocal flexibility. Many non-passerine species lacking such flexibility might therefore be more vulnerable to the negative effects on their fitness of exposure to low-frequency background noise. Species incapable of adapting their signals to background noise are predicted to disappear from noisy areas. Despite this, we show that species that lack song learning may show an adaptive response to natural noise which may develop over evolutionary timescales.

Estimating the Quality of Thermionic Cathodes for Microwave Vacuum Tubes Using the Low-Frequency Noise Parameters

Vestnik MEI ◽  
2018 ◽  
Vol 5 (5) ◽  
pp. 120-127
Author(s):  
Mikhail D. Vorobyev ◽  
◽  
Dmitriy N. Yudaev ◽  
Andrey Yu. Zorin ◽  
◽  
...  
Keyword(s):  
Low Frequency ◽  
Frequency Noise ◽  
Low Frequency Noise ◽  
Noise Parameters ◽  
Thermionic Cathodes ◽  
Vacuum Tubes

Simulation of Low Frequency Noise in a CCTWT

1999 ◽  
Author(s):  
Charles K. Birdsall ◽  
J. P. Varboncoeur ◽  
P. J. Christensen
Keyword(s):  
Low Frequency ◽  
Frequency Noise ◽  
Low Frequency Noise
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