Effects of Frequency on the Directional Auditory Sensitivity of Northern Saw-Whet Owls (Aegolius acadicus)

2021 ◽  
pp. 1-11
Author(s):  
Eileanor P. LaRocco ◽  
Glenn A. Proudfoot ◽  
Megan D. Gall
Keyword(s):  
Auditory Evoked Potentials ◽  
Transfer Functions ◽  
Low Frequency ◽  
High Sensitivity ◽  
Directional Hearing ◽  
Directional Sensitivity ◽  
Low Frequencies ◽  
Aegolius Acadicus ◽  
Spatial Locations ◽  
Prey Items

Many animals use sound as a medium for detecting or locating potential prey items or predation threats. Northern saw-whet owls (<i>Aegolius acadicus</i>) are particularly interesting in this regard, as they primarily rely on sound for hunting in darkness, but are also subject to predation pressure from larger raptors. We hypothesized that these opposing tasks should favor sensitivity to low-frequency sounds arriving from many locations (potential predators) and high-frequency sounds below the animal (ground-dwelling prey items). Furthermore, based on the morphology of the saw-whet owl skull and the head-related transfer functions of related species, we expected that the magnitude of changes in sensitivity across spatial locations would be greater for higher frequencies than low frequencies (i.e., more “directional” at high frequencies). We used auditory-evoked potentials to investigate the frequency-specific directional sensitivity of Northern saw-whet owls to acoustic signals. We found some support for our hypothesis, with smaller-magnitude changes in sensitivity across spatial locations at lower frequencies and larger-magnitude changes at higher frequencies. In general, owls were most sensitive to sounds originating in front of and above their heads, but at 8 kHz there was also an area of high sensitivity below the animals. Our results suggest that the directional hearing of saw-whet owls should allow for both predator and prey detection.

Low-Frequency Gain Compensation in Directional Hearing Aids

2002 ◽  
Vol 11 (1) ◽  
pp. 29-41 ◽  
Author(s):  
Todd Ricketts ◽  
Paula Henry
Keyword(s):  
Hearing Loss ◽  
Hearing Aids ◽  
Low Frequency ◽  
Sound Quality ◽  
Directional Hearing ◽  
Low Frequencies ◽  
Speech In Noise ◽  
Directional Microphone ◽  
Listening Environments ◽  
Gain Compensation

Hearing aids currently available on the market with both omnidirectional and directional microphone modes often have reduced amplification in the low frequencies when in directional microphone mode due to better phase matching. The effects of this low-frequency gain reduction for individuals with hearing loss in the low frequencies was of primary interest. Changes in sound quality for quiet listening environments following gain compensation in the low frequencies was of secondary interest. Thirty participants were fit with bilateral in-the-ear hearing aids, which were programmed in three ways while in directional microphone mode: no-gain compensation, adaptive-gain compensation, and full-gain compensation. All participants were tested with speech in noise tasks. Participants also made sound quality judgments based on monaural recordings made from the hearing aid. Results support a need for gain compensation for individuals with low-frequency hearing loss of greater than 40 dB HL.

scholarly journals Bioinspired Low-Frequency Material Characterisation

2012 ◽  
Vol 2012 ◽  
pp. 1-12 ◽  
Author(s):  
C. Hopper ◽  
S. Assous ◽  
P. B. Wilkinson ◽  
D. A. Gunn ◽  
P. D. Jackson ◽  
...  
Keyword(s):  
Sound Velocity ◽  
Medical Physics ◽  
Low Frequency ◽  
High Sensitivity ◽  
Prediction Errors ◽  
Low Frequencies ◽  
Longitudinal Sound Velocity ◽  
Velocity Prediction ◽  
Thickness Measurements

New-coded signals, transmitted by high-sensitivity broadband transducers in the 40–200 kHz range, allow subwavelength material discrimination and thickness determination of polypropylene, polyvinylchloride, and brass samples. Frequency domain spectra enable simultaneous measurement of material properties including longitudinal sound velocity and the attenuation constant as well as thickness measurements. Laboratory test measurements agree well with model results, with sound velocity prediction errors of less than 1%, and thickness discrimination of at least wavelength/15. The resolution of these measurements has only been matched in the past through methods that utilise higher frequencies. The ability to obtain the same resolution using low frequencies has many advantages, particularly when dealing with highly attenuating materials. This approach differs significantly from past biomimetic approaches where actual or simulated animal signals have been used and consequently has the potential for application in a range of fields where both improved penetration and high resolution are required, such as nondestructive testing and evaluation, geophysics, and medical physics.

Abstract 4666: Anatomic Substrate as Determinant of Dominant Frequency Dynamics During Human Ventricular Fibrillation

Circulation ◽  
2008 ◽  
Vol 118 (suppl_18) ◽  
Author(s):  
Karthikeyan Umapathy ◽  
Stephane Masse ◽  
Elias Sevaptsidis ◽  
John Asta ◽  
Talha Farid ◽  
...  
Keyword(s):  
Low Frequency ◽  
Electrode Array ◽  
Peak Frequency ◽  
Dominant Frequency ◽  
Physiological Factors ◽  
Low Frequencies ◽  
Bipolar Electrodes ◽  
Df Analysis ◽  
Spatio Temporal ◽  
Spatial Locations

Background: Dominant frequency (DF) analysis is a common way of quantitatively studying the spatio-temporal variation of frequency during VF. Areas of high frequencies (e.g. rotors) and low frequencies (e.g. blocks) have been associated with the occurrence and maintenance of VF. However, the relation of these high or low frequency areas to anatomical or physiological substrate remains unclear. Objective: We tested the hypothesis that the Max-Min DF locations in the epicardium during VF are due to anatomical substrate. Methods and Results: We analyzed 33, 4 seconds VF episodes acquired from 6 isolated human hearts using a Langendorff setup. The hearts were received from the heart-transplanted patients with informed consent. Electrode array consisting 112 bipolar electrodes was used to acquire the surface unipolar and bipolar electrograms from the epicardium. DF was computed as the peak frequency of the VF segment from each of electrodes using Welch’s modified periodogram method. From the DF distribution, the regions of max and min frequencies were identified for LV and RV regions. Scar maps were computed for each of the 6 hearts using a previously published method by mapping the amplitude of bipolar electrograms (<0.5mv = scar) during the pacing protocol. The areas of max-min DF frequencies in each of the VF episode were compared to the corresponding spatial locations in the scar map. Table 1 shows the match between the max-min DF frequency locations and the scar locations. 50% of max-min DF frequencies locations match the scar locations and in 97% of the matched locations the max-min DF occur at the vicinity of the scar. Conclusion: During human VF, DF dynamics are only partially explained by the anatomical substrate. This suggests that ion channel heterogeneity and dynamic physiological factors may play an important role in determining fibrillation dynamics. Match Between Max-Min DF locations and Scar Locations

scholarly journals A High-Through Technique to Measure DNA Methylation

2010 ◽  
Vol 3 ◽  
pp. GEG.S5035 ◽  
Author(s):  
Zhiming Zhang ◽  
Jian Gao ◽  
Cheng Qin ◽  
Li Liu ◽  
Haijian Lin ◽  
...  
Keyword(s):  
Dna Methylation ◽  
High Efficiency ◽  
Simple Procedure ◽  
Point Mutations ◽  
Low Frequency ◽  
High Sensitivity ◽  
Snp Analysis ◽  
Allelic Series ◽  
Low Frequencies ◽  
Powerful Approach

MethyLight is a sodium-bisulfite-dependent, quantitative, fluorescence-based, real-time PCR strategy that is used to detect and quantify DNA methylation in genomic DNA. High-throughput MethyLight allows the rapid and sensitive detection of very low frequencies of hypermethylated alleles in populations of alternated individuals. The high sensitivity and specificity of MethyLight can be applied not only to make it uniquely suited disease clinical but also quantitatively assessed of these low-frequency methylation events. Owing to its full of advantages of simple procedure, high efficiency and high sensitivity, MethyLight provides a powerful approach for clinical examination, Gene expression analysis, SNP analysis and allele analysis. Coupled with other techniques, MethyLight can be used immediately in identifying allelic alterations in genes exhibiting expressions correlating with phenotypes, Locating an allelic series of induced point mutations in genes of interest. The development of this technique should considerably enhance our ability to rapidly and accurately generate epigenetic profiles of samples.

Physiology of peripheral neurons innervating otolith organs of the squirrel monkey. III. Response dynamics

1976 ◽  
Vol 39 (5) ◽  
pp. 996-1008 ◽  
Author(s):  
C. Fernandez ◽  
J. M. Goldberg
Keyword(s):  
Squirrel Monkey ◽  
Transfer Functions ◽  
Low Frequency ◽  
Sine Wave ◽  
Saimiri Sciureus ◽  
Otolith Organs ◽  
Response Dynamics ◽  
Low Frequencies ◽  
Gain Enhancement ◽  
Wave Cycle

1. The discharge of peripheral otolith neurons in response to sinusoidal force variations was investigated in the barbiturate-anesthetized squirrel monkey (Saimiri sciureus). The sine waves were superimposed on a background force which biased the end organ so as to excite or inhibit the unit's firing. Both regularly and irregularly discharging neurons were studied. 2. The response amplitude, measured as a peak-to-peak changes in firing rate, reached near-maximal values during the first sine-wave cycle and, for most units, remained constant as sinusoidal stimulation was prolonged. 3. In regular units, introduction of an excitatory bias increased the sensitivity to sinusoidal stimulation in a manner consistent with the static asymmetries observed in the response to constant forces. Bias effects in irregular units were usually small and, in some cases, excitatory biases resulted in a decrease in sensitivity. 4. Variation in sine-wave amplitude had no effect on the sinusoidal gains or phases of regular units. For irregular units, there was some evidence of a small gain increase as stimulus amplitude decreased. 5. Nonlinear distortion was usually 10-20% and was mainly of an asymmetric type. In regular units, the distortion could be partially related to static asymmetries. 6. The response of regular units is predominantly tonic, that of irregular units more phasic. For regular units there was usually no more than a twofold gain enhancement as frequency was increased in the spectrum from DC to 2.0 Hz; typically, small phase leads at low frequencies were replaced by similar phase lags at higher frequencies. Irregular units were characterized by a 20-fold frequency-dependent gain enhancement over the same spectrum; phase leads of 20-40% were seen. 7. Bodeplots were fit by a family of transfer functions, each consisting of three terms. The first is a velocity-sensitive operator with a fractional exponent. The second is a low-frequency adaptation operator. Only the lag operator can be related to the dynamics of otoligh motion. Most of the variations among units, including those seen between regular and irregular units, can be accounted for by suitable variations in the velocity-sensitive and adaptation operators. 8. The transfer functions, when integrated and inverted, led to reasonable approximations of the response to force trapezoids. It is concluded that the transfer functions provide an adequate representation of the dynamic behavior of most units. The only exceptions are the few neurons showing delayed adaptation.

scholarly journals Benefits of Binaural Integration in Cochlear Implant Patients with Single-Sided Deafness and Residual Hearing in the Implanted Ear

Life ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 265
Author(s):  
Artur Lorens ◽  
Anita Obrycka ◽  
Piotr Henryk Skarzynski ◽  
Henryk Skarzynski
Keyword(s):  
Cochlear Implant ◽  
Sound Localization ◽  
Low Frequency ◽  
Hearing Preservation ◽  
Residual Hearing ◽  
Low Frequencies ◽  
Monosyllabic Words ◽  
Localization Ability ◽  
Single Sided Deafness ◽  
Spatial Locations

The purpose of the study is to gauge the benefits of binaural integration effects (redundancy and squelch) due to preserved low-frequency residual hearing in the implanted ear of cochlear implant users with single-sided deafness. There were 11 cochlear implant users (age 18–61 years old) who had preserved low-frequency hearing in the implanted ear; they had a normal hearing or mild hearing loss in the contralateral ear. Patients were tested with monosyllabic words, under different spatial locations of speech and noise and with the cochlear implant activated and deactivated, in two listening configurations—one in which low frequencies in the implanted ear were masked and another in which they were unmasked. We also investigated how cochlear implant benefit due to binaural integration depended on unaided sound localization ability. Patients benefited from the binaural integration effects of redundancy and squelch only in the unmasked condition. Pearson correlations between binaural integration effects and unaided sound localization error showed significance only for squelch (r = −0.67; p = 0.02). Hearing preservation after cochlear implantation has considerable benefits because the preserved low-frequency hearing in the implanted ear contributes to binaural integration, presumably through the preserved temporal fine structure.

scholarly journals Hearing in 3D: Directional Auditory Sensitivity of Northern Saw-Whet Owls (Aegolius acadicus)

2020 ◽  
Vol 60 (5) ◽  
pp. 1058-1067 ◽  
Author(s):  
Megan de Koning ◽  
Julia R Beatini ◽  
Glenn A Proudfoot ◽  
Megan D Gall
Keyword(s):  
Auditory Processing ◽  
Auditory Evoked Potentials ◽  
Dimensional Space ◽  
Median Plane ◽  
Open Loop ◽  
Spatial Segregation ◽  
Directional Sensitivity ◽  
Sound Sources ◽  
Masking Noise ◽  
Aegolius Acadicus

Abstract Northern saw-whet owls (Aegolius acadicus) are nocturnal predators that are able to acoustically localize prey with great accuracy; an ability that is attributed to their unique asymmetrical ear structure. While a great deal of research has focused on open loop sound localization prior to flight in owls (primarily barn owls), directional sensitivity of the ears may also be important in locating moving prey on the wing. Furthermore, directionally sensitive ears may also reduce the effects of masking noise, either from the owls’ wings during flight or environmental noise (e.g., wind and leaf rustling), by enhancing spatial segregation of target sounds and noise sources. Here, we investigated auditory processing of Northern saw-whet owls in three-dimensional space using auditory evoked potentials (AEPs). We simultaneously evoked auditory responses in two channels (right and left ear) with broadband clicks from a sound source that could be manipulated in space. Responses were evoked from 66 spatial locations, separated by 30° increments in both azimuth and elevation. We found that Northern saw-whet owls had increased sensitivity to sound sources directly in front of and above their beaks and decreased sensitivity to sound sources below and behind their heads. The spatial region of highest sensitivity extends from the lower beak to the crown of the head and 30° left or right of the median plane, dropping off beyond those margins. Directional sensitivity is undoubtedly useful during foraging and predator evasion, and may also reduce the effect of masking noise from the wings during flight due to the spatial segregation of the noise and targets of interest.

scholarly journals The Low frequency Space Array (LFSA)

1988 ◽  
Vol 129 ◽  
pp. 459-460
Author(s):  
K. W. Weiler ◽  
B. K. Dennison ◽  
K. J. Johnston ◽  
R. S. Simon ◽  
J. H. Spencer ◽  
...  
Keyword(s):  
High Resolution ◽  
Milky Way ◽  
Low Frequency ◽  
High Sensitivity ◽  
Electromagnetic Spectrum ◽  
Low Frequencies ◽  
Frequency Space ◽  
Physical Limit ◽  
Path Lengths ◽  
Fundamental Physical

At the lowest radio frequencies (≤30 MHz), the Earth's ionosphere transmits poorly or not at all. This relatively unexplored region of the electromagnetic spectrum is thus an area where high resolution, high sensitivity observations can open a new window for astronomical investigations. Also, extending observations down to very low frequencies brings astronomy to a fundamental physical limit where the Milky Way becomes optically thick over relatively short path lengths due to diffuse free-free absorption.

Transfer function of sound transmission in subglottal human respiratory system at low frequencies

1990 ◽  
Vol 69 (6) ◽  
pp. 2126-2130 ◽  
Author(s):  
G. R. Wodicka ◽  
D. C. Shannon
Keyword(s):  
Chest Wall ◽  
Transfer Functions ◽  
Low Frequency ◽  
Sound Transmission ◽  
Spectral Energy ◽  
Thoracic Cavity ◽  
Low Frequencies ◽  
Cavity Resonances ◽  
Healthy Adult Male ◽  
Effective Transfer

The amplitude of sound transmission from the mouth to a site overlying the extrathoracic trachea and two sites on the posterior chest wall was measured in eight healthy adult male subjects at resting lung volume over the 100- to 600-Hz frequency range. The ratios of the estimated magnitude spectra of transmission of each of the chest wall sites to the tracheal site were determined, with the resulting spectra representing effective transfer functions of transmission in the subglottal system. For the group, the transfer functions exhibited a single peak, which occurred at 143 +/- 13 Hz (mean +/- SD) with a quality factor (Q) of 2.0 +/- 0.2 for the upper chest wall site and at 129 +/- 6 Hz with a Q of 2.2 +/- 0.4 for the lower site. The trend of decreasing spectral energy with increasing frequency was indicated by roll-offs of -10 +/- 4 and -17 +/- 5 dB/octave from 300 to 600 Hz at the two sites, respectively. The fundamental radial mode of a model thoracic cavity, which is a large rigid cylinder filled with lossless lung tissue, provides a good estimate of the observed low-frequency resonance. This agreement suggests that thoracic cavity resonances may have particularly important effects on sound transmission at frequencies below approximately 250 Hz, where the magnitude of parenchymal attenuation appears to be small.

scholarly journals Properties and magnetic origins of solar S-bursts

2019 ◽  
Vol 622 ◽  
pp. A204 ◽  
Author(s):  
Brendan P. Clarke ◽  
Diana E. Morosan ◽  
Peter T. Gallagher ◽  
Vladimir V. Dorovskyy ◽  
Alexander A. Konovalenko ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Solar Activity ◽  
Solar Radio ◽  
Low Frequency ◽  
High Sensitivity ◽  
Coronal Magnetic Field ◽  
Solar Radio Emission ◽  
Radio Bursts ◽  
Burst Source ◽  
Low Frequencies

Context. Solar activity is often accompanied by solar radio emission, consisting of numerous types of solar radio bursts. At low frequencies (<100 MHz) radio bursts with short durations of milliseconds, such as solar S-bursts, have been identified. To date, their origin and many of their characteristics remain unclear. Aims. We report observations from the Ukrainian T-shaped Radio telescope, (UTR-2), and the LOw Frequency ARray (LOFAR) which give us new insight into their nature. Methods. Over 3000 S-bursts were observed on 9 July 2013 at frequencies of 17.4–83.1 MHz during a period of low solar activity. Leading models of S-burst generation were tested by analysing the spectral properties of S-bursts and estimating coronal magnetic field strengths. Results. S-bursts were found to have short durations of 0.5–0.9 s. Multiple instruments were used to measure the dependence of drift rate on frequency which is represented by a power law with an index of 1.57. For the first time, we show a linear relation between instantaneous bandwidth and frequency over a wide frequency band. The flux calibration and high sensitivity of UTR-2 enabled measurements of their fluxes, which yielded 11 ± 3 solar flux units (1 SFU ≡ 104 Jy). The source particle velocities of S-bursts were found to be ∼0.07 c. S-burst source heights were found to range from 1.3 R⊙ to 2 R⊙. Furthermore, a contemporary theoretical model of S-burst generation was used to conduct remote sensing of the coronal magnetic field at these heights which yielded values of 0.9–5.8 G. Within error, these values are comparable to those predicted by various relations between magnetic field strength and height in the corona.

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