Dominant Low Frequency Research Articles

Monomorphic call structure and dimorphic vocal phenology in a sex-role reversed frog

Sexual signals in different animals are expected to be dimorphic when both sexes signal, but cases of monomorphism are known to occur, and we lack a clear understanding about the factors that modulate the level of sexual dimorphism in signals. In this study, we evaluated the hypothesis that the lack of dimorphism in sexual signals might evolve in systems experiencing temporal changing conditions of intra-sexual competition. We used the Darwin’s frog (Rhinoderma darwinii), a species with paternal care, as a model. We compared advertisement calls and examined call distinctiveness among females, pregnant and non-pregnant males in a wild population from Chiloe island, Chile. We also recorded the vocal activity of both sexes along the reproductive season. Additionally, we compared the acoustic properties of their advertisement calls in terms of sexual distinctiveness and individual repeatability. We found that the proportion of females and pregnant males vocalizing changed over time following distinct patterns. Females produced calls with lower dominant frequency and longer note and call durations than males, and these acoustic differences were related to body size differences between sexes, but only dominant frequency contributed significantly to the distinctiveness of calls between sexes. Also, individual repeatability was high, indicating that calling can be relevant for social recognition. Overall, our results suggest that mutual selective pressures could be involved in the limited dimorphism of the advertisement calls in Darwin’s frogs, as the sex ratio of individuals vocalizing (i.e. females vs. reproductive males) is reversed along the breeding period. Whether sexually monomorphic signals are evidence of adaptive mutual choice or a by-product of genetic constraints on females remains as an open question. In species with exclusive parental care of males, it would be expected that males and females alternate their reproductive availability while performing slightly differentiated sexual signals. Using acoustic recordings and capture-recapture data of the Darwin’s frog, we found that advertisement calls of this frog tend to be monomorphic. Interestingly, the males performing parental care were calling actively and the population had a clear bias in the number of males. Males and females of this endangered frog called actively, but the vocalization rate of each sex peaked at different times along the breeding season. These findings open new questions about the mechanisms of sexual recognition under restricted signal dimorphism.

Experimental Study on AE Characteristics of Granite under Uniaxial Tension at Different Strain Rates

To investigate the acoustic emission (AE) characteristics of quasi-brittle materials like rock and concrete, and to further analyze their damage and failure mechanism under seismic and other dynamic loads, the uniaxial tension test of granite cylinder specimens within the strain rate range of 10−7-10−4 s−1 was monitored by AE technology, and the typical AE characteristic parameters were analyzed using statistical and correlation analysis. The experimental results show that, with the increase of strain rate, the peak of AE hit rate appears earlier and increases; the proportion of AE hits with higher duration or amplitude increases significantly, the b-value shows a decreasing trend, and the distribution of AE frequency-amplitude is increasingly discrete. In addition, the obvious characteristic of double dominant frequency bands was observed in AE waveforms by using spectrum analysis, with the increase of strain rate, the percentage of A-type waveforms corresponding to low dominant frequency band increases, while that of D-type waveforms corresponding to high ones decreases accordingly, which is significance for the further study of the damage and failure mechanism of quasi-brittle materials.

Analysis of potential low frequency resonance between a 1GW MMC HVDC and a nearby nuclear generator

This paper presents a comprehensive analytical eigenvalue stability study of subsynchronous torsional interactions between the 1 GW Eleclink MMC HVDC and the 1.12 GW Gravelines turbine-generator in north France. It revalidates the conclusions of previous studies on VSC-based HVDC systems by showing that the risk of SSTI may be of significance when the HVDC is based on the MMC and not the two level VSC technology. The study demonstrates that in the case of the weak French grid and the rated HVDC power flow from France to England, the HVDC can destabilize the dominant low frequency, 6.3 Hz, torsional mode. The analysis also expands the work of previous studies on MMC and reveals that the case of the HVDC power flow from the English to the French grid may also introduce the risk of destabilizing the lower frequency mode. Furthermore, it also reveals a noticeable impact of the PLL and that increasing the gains has an opposite effect on the two HVDC power flow directions. Moreover, participation factors are analyzed for the 6.3 Hz mode indicating that the main cause of the torsional interactions is the HVDC power control loop. The main findings are verified on the detailed EMTP model.

A novel class of reconfigurable parallel kinematic manipulators: Concepts and Fourier-based singularity analysis

In-situ interventions in complex environments require new concepts of Parallel Kinematic Manipulators (PKMs) that present higher versatility for adapting to unstructured working environments without affecting their advantageous characteristics. To address this opportunity a novel class of adaptive PKMs is proposed, the upper joints are repositionable on the moving platform and the lower joints are free from a base. These characteristics give to the proposed PKMs the capability to modify its workspace and performance (i.e. stiffness and singularity avoidance) to work on non-conventional manufacturing/repair environments. Further, the kinematic and workspace models of the proposed PKMs are introduced. More importantly, a unique method for singularity analysis is introduced, as the versatility to modify the workspace comes with the disadvantage of singularities that are not constant. To address this issue a strategy based on the Fourier transform is introduced, the dominant frequencies are identified and configurations with lower dominant frequencies are weighted to stabilise the Jacobian of the parallel mechanism. Finally, a set of validations are presented for proving the proposed method of singularity analysis by FEA with an error smaller than 1%.

A new method for determining the crack classification criterion in acoustic emission parameter analysis

At a microscopic scale, the failure of brittle materials results from crack initiation, propagation and coalescence. Acoustic emission (AE) technique, especially parameter analysis, has been widely applied to investigate cracking process and mechanism in civil engineering. However, crack classification in AE parameter analysis mostly derives from the empirical relation between the RA value and the average frequency, and the crack classification criterion, i.e., the optimal transition line between shear and tensile cracks in the parameter analysis has not been determined yet. Based on statistical analysis of dominant frequency characteristics of AE signals, a new method is proposed for determining the optimal transition line for crack classification in AE parameter analysis. Spectrum analyses of AE waveform data in the representative specimens are carried out to acquire the dominant frequency of AE waveforms. Proportions of waveforms distributed in low and high dominant frequency bands (L-type and H-type waveforms) are determined. The ratios of tensile and shear cracks, viewed as measurements, are determined by the statistical analysis of dominant frequency characteristics of AE waveforms. For a series of different transition line, the predicted ratios of tensile and shear cracks in AE parameter analysis are determined. The optimal transition line is determined to be the one corresponding to the least square difference between predicted data and measurements. The determined optimal transition line can be directly applied for crack classification in AE parameter analysis in the subsequent experiments of this brittle material. The reliability of the proposed method were validated by laboratory tests of rock subjected to compression. It can be found that the optimal transition line in the parameter analysis is approximately from 1:100 to 1:500 for brittle rock under compression. The findings in this study contributes to the enhancement of the accuracy and efficiency of AE source mechanism and damage process analysis.

High-fold enhancement of a seismic image and detection of the low-frequency shadow below the bottom-simulating reflector

Gas hydrates are a potential energy source. Seismic methods have been extensively applied to detecting gas hydrates based on the interpretation of bottom-simulating reflectors (BSRs), for which the seismic response is characterized by many features such as a strong reflection and low-frequency shadow (LFS). Moreover, the frequency content depends of the offset, with the BSR response having a lower dominant frequency at large offsets. In this work, we intend to enhance the low amplitude of the BSR and to observe the LFS phenomena at the southern Hikurangi margin of New Zealand. To improve the resolution of the seismic image, we processed a multichannel seismic profile acquired over a distance of 125 km. The standard processing sequence for seismic reflection data has been performed with an emphasis on using high fold. The results reveal that the BSR is characterized by strong reflections and high amplitude owing to the seismic data being stacked at higher fold. In addition, a continuation of the BSR event was obtained. Moreover, the use of a higher fold allowed us to determine an LFS below the BSR event, which indicates the presence of gas. The findings support other evidence obtained through contemporary studies on identifying gas hydrates using seismic methods.

Traffic noise differentially impacts call types in a Japanese treefrog (Buergeria japonica)

AbstractAcoustic noise from automobile traffic impedes communication between signaling animals. To overcome the acoustic interference imposed by anthropogenic noise, species across taxa adjust their signaling behavior to increase signal saliency. As most of the spectral energy of anthropogenic noise is concentrated at low acoustic frequencies, species with lower frequency signals are expected to be more affected. Thus, species with low‐frequency signals are under stronger pressure to adjust their signaling behaviors to avoid auditory masking than species with higher frequency signals. Similarly, for a species with multiple types of signals that differ in spectral characteristics, different signal types are expected to be differentially masked. We investigate how the different call types of a Japanese stream breeding treefrog (Buergeria japonica) are affected by automobile traffic noise. Male B. japonica produce two call types that differ in their spectral elements, a Type I call with lower dominant frequency and a Type II call with higher dominant frequency. In response to acoustic playbacks of traffic noise, B. japonica reduced the duration of their Type I calls, but not Type II calls. In addition, B. japonica increased the call effort of their Type I calls and decreased the call effort of their Type II calls. This result contrasts with prior studies in other taxa, which suggest that signalers may switch to higher frequency signal types in response to traffic noise. Furthermore, the increase in Type I call effort was only a short‐term response to noise, while reduced Type II call effort persisted after the playbacks had ended. Overall, such differential effects on signal types suggest that some social functions will be disrupted more than others. By considering the effects of anthropogenic noise across multiple signal types, these results provide a more in‐depth understanding of the behavioral impacts of anthropogenic noise within a species.

PEMETAAN MIKROZONASI DAERAH RAWAN GEMPABUMI MENGGUNAKAN METODE HVSR DAERAH PAINAN SUMATERA BARAT

Regional Painan, the distric of Pesisir Selatan, the province of west Sumatera is one of the areas with high risk disaster prone. This study aims attempts to maped the disaster prone area of the Painan region based on the dominant frequency value, Vs30, PGA and amplification and to know the value of ground movement from the area. By using the HVSR method (Horizontal to Vertical Spectra Ratio) expected to assist to zone the regions. Based on the research that has been done, it is known that the Painan area, West Sumatera, have values of dominant frequency between 0.6 to 12.07 Hz. As for the value Vs30 between 73.08 to 1449 m/s and the amplification values between 0.47 to 6.01. The PGA value for Painan region between 0.034 to 0.063 g. Based on the analysis that has been done by correlating the four zoning map, it is known that the area which has a high risk of earthquake disaster that is estimated to coastal areas. This is supported by the dominant low frequency value and the value Vs30 small and PGA of high value. The amplification value of this region is divided into four zones, areas that have amplification is very high being around the beach and composed by rock alluvial, the value of amplification of high contained in nearly all the regions Painan while amplification medium and low are the small area of Painan and the small area of Bungo Pasang Salido because based on the geological map of the area is composed of two types of rocks are alluvial and rock Painan Formations.

Both sexes produce sounds in vocal fish species: testing the hypothesis in the pygmy gourami (labyrinth fishes).

In vocal fish species, males possess larger sound-generating organs and signal acoustically with pronounced sex-specific differences. Sound production is known in two out of three species of croaking gouramis (Trichopsis vittata and T. schalleri). The present study investigates sex-specific differences in sonic organs, vocalizing behaviour and sounds emitted in the third species, the pygmy gourami, T. pumila, in order to test the hypothesis that females are able to vocalize despite their less-developed sonic organs, and despite contradictory reports. Croaking gouramis stretch and pluck two enhanced (sonic) pectoral fin tendons during alternate fin beating, resulting in a series of double-pulsed bursts, termed croaking sound. We measured the diameter of the first and second sonic tendon and showed that male tendons were twice as large as in similar-sized females. We also determined the duration of dyadic contests, visual displays, number of sounds and buttings. Sexes differ in all sound characteristics but in no behavioural variable. Male sounds consisted of twice as many bursts, a higher percentage of double-pulsed bursts and a higher burst period. Additionally, male sounds had a lower dominant frequency and a higher sound level. In summary, female pygmy gouramis possessed sonic organs and vocalized in most dyadic contests. The sexual dimorphism in sonic tendons is clearly reflected in sex-specific differences in sound characteristics, but not in agonistic behaviour, supporting the hypothesis that females are vocal.

Wake meandering in a model wind turbine array in a high Reynolds number turbulent boundary layer

Wake meandering is the dynamic shift observed in the spatial location of a wind turbine wake as it evolves downstream, considered to be caused primarily by the interaction of large flow structures in the atmospheric boundary layer with the turbulent wake. Experiments were conducted in a large boundary layer wind tunnel to investigate meandering in the wakes of both individual model wind turbines and in a wind turbine array with a large number of model turbines (19 rows x 5 columns = 95 model turbines). Unlike bluff body vortex shedding, the meandering phenomenon for a turbine wake is not characterized by a well-pronounced peak in the frequency domain, but rather by a broad spread over a low-frequencies range. For individual turbine models, both rotating three-bladed models and non-rotating porous disks, frequencies and peak energies observed in the velocity spectrum in the wake return to those of the incoming high Reynolds number turbulent boundary layer. Wake meandering also presents itself in the large wind turbine array. Here, frequencies and peak energies observed in the velocity spectrum in the wake do not return to those of the incoming turbulent boundary layer. Instead, a lower dominant frequency corresponding to the wind velocity at hub height and array spacing is observed within the array, indicating forcing of the meandering by the array itself (a type of resonance). Higher peak energies are observed in the array due to large flow structures representative of the turbine spacing.

Passive monitoring of phenological acoustic patterns reveals the sound of the camouflage grouper, Epinephelus polyphekadion

Abstract Passive acoustic monitoring (PAM) is a non‐invasive technique that uses hydrophones to monitor populations and ecosystem dynamics. Although many applications of PAM have been developed in recent years, it has never been used to identify a calling marine species. The south pass of Fakarava Atoll, French Polynesia, hosts spawning events of many reef fish species, including the camouflage grouper Epinephelus polyphekadion, with a spawning aggregation abundance exceeding 17 000 individuals during the full moons of June and July. The current study aimed to use PAM to distinguish camouflage grouper sounds among the vocal activities of all fish recorded during the aggregation periods. Audio recordings analysis resulted in the identification of 29 sound types, some of which showed diel and lunar patterns. Temporal analysis of these sounds in relation to spawning activities allowed the identification of camouflage grouper calls. These calls can be described as a single pulse or a series of ‘boom(s)’ with a pulse duration of ~44 ms and a low dominant frequency of 103 ± 31 Hz. Video recordings show that the camouflage grouper produces the ‘booms’ to initialize spawner ascent and to promote synchronous gamete release into the water column. The study highlights for the first time that PAM can be used to identify the previously unknown sound of a fish species. Moreover, we can use it to understand the phenology of some biological activities for improving the resolution of fish biodiversity assessments.

Deep Low‐Frequency Earthquakes Associated With the Eruptions of Shinmoe‐dake in KirishimaVolcanoes

AbstractDeep low‐frequency (DLF) earthquakes occur beneath the Kirishima volcanoes in southwest Japan at depths of 10–30 km. In this study, we aim to reveal the relationship between DLF earthquakes and volcanic activity including eruptions by relocating the hypocenters of the earthquakes using the network correlation coefficient method and detecting the earthquakes comprehensively using the matched filter technique. Hypocenters of DLF earthquakes are found to be concentrated in some separated small clusters within depths of 10–15 and 20–27 km. Activation of deeper DLF earthquakes had been observed for approximately 2 years from December 2009, during which various styles of eruptions occurred. Such a 2‐year increase in DLF seismicity was well correlated with crustal deformation because of the volume change of a magma reservoir. The waveforms and hypocenters of DLF earthquakes during the activation period were different from those during other time periods. The activated DLF earthquakes mostly had low dominant frequencies and were located in four deeper clusters. The activation of each cluster was switched 3 times at the transition of the eruption styles. These results suggest that DLF earthquakes might occur near magma sills and could be triggered by fluid flow in the changing paths by complex eruption processes. In addition, the waveforms and hypocenters of DLF earthquakes associated with the 2018 eruptions are different from those associated with the 2011 eruptions. The fluid paths of the 2018 eruptions might be different from those of the 2011 eruptions.

Vocalisation and its association with androgens and corticosterone in a night frog (Nyctibatrachus humayuni) with unique breeding behaviour

AbstractIn anurans, vocalisation is used to communicate within and between the sexes during reproduction. Knowledge of vocal repertoire and its diversity is essential in understanding its significance in sexual selection. In this context, we studied the vocal behaviour of Nyctibatrachus humayuni and quantified the urinary metabolites of androgens and corticosterone to understand the associations among hormones, body condition index and vocalisation. Our results show that males of N. humayuni produce an amplitude‐modulated call consisting of a train of pulses. Interestingly, a high degree of inter‐individual variation was observed in the call parameters. The dominant frequency and pulse interval were negatively correlated with male body size, whereas pulse duration and pulse duty cycle were positively correlated with it. Dominant frequency was negatively correlated with androgens and corticosterone, whereas pulse interval was negatively correlated with corticosterone. Further, pulse duty cycle, pulse duration and pulses per call were positively associated with corticosterone. Surprisingly, none of the acoustic parameters was associated with male body temperature and body condition. A significant variation was evident in the vocal effort, dominant frequency and amplitude of advertisement calls produced under different social situations. Calls produced during territory establishment had lower dominant frequency but higher vocal effort, whereas those produced during courtship had higher amplitude and vocal effort than the calls produced in the absence of a competitor/female. Our results suggest that greater inter‐male variability in the advertisement call of N. humayuni could be important in female choice as it may help females to assess the quality of a male. Further, androgens and corticosterone could be important in modulating crucial parameters of the advertisement call.

Disturbance calls of five migratory Characiformes species and advertisement choruses in Amazon spawning sites.

Species-specific disturbance calls of five commercially-important characiform species are described, the Curimatidae commonly called branquinhas: Potamorhina latior, Potamorhina altamazonica and Psectrogaster amazonica; Prochilodontidae: jaraquí Semaprochilodus insignis and curimatã Prochilodus nigricans. All species have a two-chambered swimbladder and the sonic mechanism, present exclusively in males, utilises hypertrophied red muscles between ribs that adhere to the anterior chamber. The number of muscles is unusually plastic across species and varies from 1 to 4 pairs suggesting considerable evolution in an otherwise conservative system. Advertisement calls are produced in river confluences in the Madeira Basin during the high-water mating season (January-February). Disturbance calls and sampling allowed recognition of underwater advertisement choruses from P. latior, S. insignis and P. nigricans. The advertisement calls of the first two species have largely similar characteristics and they mate in partially overlapping areas in the Guaporé River. However, P. latior sounds have a lower dominant frequency and it prefers to call from river confluences whereas S. insignis shoals occur mostly in the main river channel adjacent to the confluence. These results help identify and differentiate underwater sounds and evaluate breeding areas during the courtship of commercially important characids likely to be affected by two hydroelectric dams.

Investigation of vented hydrogen-air deflagrations in a congested vessel

Experiments were conducted in a 1-m3 rectangular vessel with a 700 mm × 400 mm top vent to investigate the effects of cylinders placed parallel to the venting direction on vented hydrogen-air deflagrations and the structural response of the vessel wall to an explosion. Three pressure peaks, which corresponded to the opening of the vent cover, venting of the burnt gas mixtures, and the occurrence of the external explosion, respectively, were observed. The pressure peak corresponding to the external explosion always dominated the pressure-time histories, and the maximum internal overpressure was reached at the bottom of the vessel. The presence of cylinders in the vessel affected the explosion venting significantly. When more cylinders were placed, the maximum internal and external overpressure increased, whereas the amplitude of pressure oscillation and the time needed to reach the maximum overpressure decreased. A close relation between the pressure oscillation and vessel vibration was found. Low and high dominant frequency spectra of vessel vibration were observed in all tests. The former resulted from the acoustic oscillation of the internal pressure, and the latter corresponded to the resonance of the vessel, which may react against the flame and result in pressure oscillation with a frequency comparable with the natural frequency of the vessel.

Characteristics of source wavelets generated by two sparkers

ABSTRACT Sparker is used as an explosive seismic source in high-resolution oceanic explorations, however, further analysis is necessary to evaluate the source level, dominant frequency, and bandwidth of the generated source wavelets. In this study, we investigated source wavelets produced by two commercial sparkers with a multi-electrode array. All recorded signals were obtained in shallow water. A SIG 5mille (Services and Instruments of Geophysique) sparker generates a typical wavelet with an expansion pulse, ghosts and a notable collapse pulse, whereas the collapse pulse generated by a ZJUPSS (Plasma Seismic Source of Zhejiang University) sparker is much weaker because of the lower discharge energy per electrode. Nevertheless, the ZJUPSS expansion pulse magnitude is substantially higher than that of the SIG 5mille, and the former's sound source level reaches 223 dB at only 900 J. The SIG 5mille expansion pulse width is broader than that of the ZJUPSS, resulting in a lower dominant frequency down to 232 Hz at 2500 J, but the latter has more high-frequency components leading to better vertical resolution. The acoustic energy efficiency of the ZJUPSS ranges up to 4% higher than that of the SIG 5mille (

Dephasing and relaxational polarized sub-Ohmic baths acting on a two-level system.

We study a quantum two-level system under the influence of two independent baths, i.e., a sub-Ohmic pure dephasing bath and an Ohmic or sub-Ohmic relaxational bath. We show that cooling such a system invariably polarizes one of the two baths. A polarized relaxational bath creates an effective asymmetry. This asymmetry can be suppressed by additional dephasing noise. This being less effective, the more dominant low frequencies are in the dephasing noise. A polarized dephasing bath generates a large shift in the coherent oscillation frequency of the two-level system. This frequency shift is little affected by additional relaxational noise nor by the frequency distribution of the dephasing noise itself. As our model reflects a typical situation for superconducting phase qubits, our findings can help optimize cooling protocols for future quantum electronic devices.

Influence of Water on the Fracture Process of Marble with Acoustic Emission Monitoring

Water has a great influence on rock fracture process, and it is necessary to explore the activity of cracks for saturated rocks at key stress points. By uniaxial compression test and acoustic emission (AE) tests, four key points of stress-strain curve for dry and saturated marble specimens are determined. Those four key stress points include: crack closure stress (point A), crack initiation stress (point B), crack damage stress (point C) and peak stress (point D). By analyzing dominant frequencies and amplitude of AE waveforms of the whole loading process and in the vicinity of key points, the fracture process of samples was studied. The results show that there are two concentrations of dominant frequency bands in both dry and saturated marble, and the ranges of dominant frequency bands of the saturated seem wider. Due to the existence of water, the number and energy of AE waveforms decrease relatively during the whole test. This phenomenon indicates that water enhances the ductility and creep characteristics of rock. The appearance of lots of AE waveform signals with low dominant frequency is the precursor information of intense crack propagation and failure for dry rock, and the effects of water increased the number of micro-tensile failures for saturated rock in the vicinity of each key point. From point A, point B, point C to point D, the proportions of H-type bands in the vicinity of each key point for dry rock show a trend of increasing — decreasing — sharply decreasing, while those for saturated rock follow the law of increasing — decreasing — increasing.

Preterm modulation of connectivity by endogenous generators: The theta temporal activities in coalescence with slow waves

Background The neuronal activity of the preterm brain is characterized by various endogenous activities whose roles in neurodevelopmental maturation processes have not been fully elucidated. The preterm EEG is characterized by discontinuities composed of short bursts of activity with dominant low frequencies. One of the earliest endogenous activities is the theta temporal activity in coalescence with slow waves (TTA-SW), which appears at 24 to 32 weeks of gestational age (wGA). Objectives The present study investigated the influence of TTA-SW on the spatial organization of the early preterm brain network. Methods High-Density EEG (HD-EEG) data were recorded from preterm infants (29–32 wGA) and functional connectivity (FC) was estimated from the scalp EEG. Results TTA-SW, particularly in the theta band, induced increased FC between left temporal and left frontal areas and between left temporal and parietal areas with TTA-SW at the left temporal region, while FC was limited to the right temporal regions in the case of TTA-SW at the right temporal region. Regardless of the lateralization of TTA-SW, long-range FCs were observed between left frontal to left parietal areas, suggesting that these regions, together with the temporal region, provide a basis for coherent neuronal activation across distal cortical regions. Conclusion TTA-SW dynamic features showed that brief phases of TTA-SW had an impact on both local and whole brain network organization, supporting the importance of TTA-SW as a biomarker of brain development.

The sound of a blood meal: Acoustic ecology of frog‐biting midges (Corethrella) in lowland Pacific Costa Rica

AbstractAnimal communication systems are often exploited by eavesdropping antagonists, especially predators and ectoparasites. Female frog‐biting midges (Diptera: Corethrellidae) are known to use male anuran advertisement calls to locate their blood hosts, frogs. Here, we use acoustic midge traps broadcasting synthetic and recorded calls to identify those frog call parameters that affect midge attraction. At our study site in Pacific lowland Costa Rica, we found that overall midge attraction was influenced by both spectral and temporal acoustic parameters. Low dominant frequencies (below 1 kHz) and short pulse durations (between 125 and 500 ms) attracted the highest numbers of midges in tests with synthetic sinusoidal pure tones. These preferences partially explained the relative attractiveness of the advertisement calls of ten local frog species. The advertisement calls of the common and widespread Giant Bullfrog, Leptodactylus savagei (Anura: Leptodactylidae), attracted by far the largest number of midges, suggesting that this frog species might be a key resource for frog‐biting midges in Costa Rica. Although we found that calls of different frog species attracted different midge species/morphospecies in statistically different proportions, acoustic niche differentiation among midge species appeared to be moderate, suggesting either a limited degree of host specialization or the use of additional short‐range, that is, chemical, host recognition cues.