Acoustic-induced motion of the bushcricket (Mecopoda elongata, Tettigoniidae) tympanum

Bushcrickets have a tonotopically organised hearing organ, the so-called crista acustica, in the tibia of the forelegs. This organ responds to a frequency range of about 5–80 kHz and lies behind the anterior tympanum on top of a trachea branch. We analyzed the sound-induced vibration pattern of the anterior tympanum, using a Laser-Doppler-Vibrometer Scanning microscope system, in order to identify frequency-dependent amplitude and phase of displacement. The vibration pattern evoked by a frequency sweep (4–79 kHz) showed an amplitude maximum which would correspond to the resonance frequency of an open tube system. At higher frequencies of about 30 kHz a difference in the amplitude and phase response between the distal and the proximal part of the tympanum was detected. The inner plate of the tympanum starts to wobble at this frequency. This higher mode in the motion pattern is not explained by purely acoustic characteristics of the tracheal space below the tympanum but may depend on the mechanical impedance of the tympanum plate. In accordance with a previous hypothesis, the tympanum moves over the whole tested frequency range in the dorso-ventral direction like a hinged flap with the largest displacement in its ventral part and no higher modes of vibration.     

Female phonotaxis and frequency discrimination in the bushcricket Requena verticalis

ABSTRACT. The male bushcricket, Requena verticalis , calls with a signal containing two predominant frequencies, 16 kHz and 28 kHz. A synthesized call, made from a template of the natural call, was played to females under conditions of a two-speaker trial on a flat arena. Orientation pathways to a speaker emitting only a 16 kHz signal were more circuitous than the pathways made by females orientating to a speaker emitting only a 28 kHz signal. Females preferred a signal with both carrier frequency peaks present within the song to a signal with only a 16 kHz or 28 kHz carrier frequency, when the signal containing a double peak was kept at equivalent absolute intensity to that with a single peak. Females chose signals containing a more powerful high frequency peak over a signal in which both peaks were balanced. For the higher peak, they were able to differentiate between frequencies with a separation of 8 kHz but not of 4 kHz. They were unable to differentiate between frequencies with a separation up to 8 kHz in the lower peak when one frequency was held at 16 kHz; however, when this frequency was held at 18 kHz, females were able to distinguish between frequencies with a difference of 4 kHz. ( N.B. 18 kHz is 2 kHz above the mean value for this frequency within the natural population.) We conclude that females are choosing males on the amount of power in the higher frequency range of their song and that this may be equivalent to a close calling male in the field.     

双频超声强化提取黄柏中小檗碱的研究

设计25kHz和40kHz的双频超声强化装置,以黄柏为对象提取小檗碱,结果表明：25kHz与40kHz双频超声强化5min,提取率为64．1％,25kHz及40kHz超声30min,提取率分别为52．9％和45．2％,双频超声强化的提取率显著高于单频超声强化的提取率。研究还表明,双频超声强化可以降低提取温度,缩短提取时间,为热敏性药物的提取提供了新的强化方法。     

骨导声诱发的耳声发射耳蜗图

用不同频率的短纯音骨导刺激,在7名(14耳)听力正常受试者同时记录双耳声诱发耳声发射(EOAE)。此法比单耳轮流记录省时一半。研究结果表明,EOAE 为一种窄带声,其中心频率随刺激声频率增高而增高,提示 EOAE 产生部位在接受刺激声频率对应的耳蜗部位附近。EOAE 的潜伏期与刺激强度无明显关系,但有随刺激声频率增高而变短的趋势,可能与不同频率刺激声诱发的 EOAE 在基底膜上产生的部位与鼓膜之间的距离不等有关。除1耳用4.0kHz 外,用1.0,2.0,3.0和4.0kHz 短纯音刺激在14耳全可记录到 EOAE,0.5kHz和6.0kHz 则分别在10耳和7耳记录到 EOAE。0.5—6.0kHz 短纯音诱发的 EOAE 的阈值均值连线所得的声发射耳蜗图上可见,1.0kHz 处阈值最低,而在这些受试者所测得的中耳共振频率平均值为1100±230Hz,推测1.0kHz EOAE 阈值最低与中耳的传导函数有关。本文描述的骨导双耳同时记录 EOAE 并描记声发射耳蜗图的方法可用于临床的听力客观评价。     

Behavioral and physiological studies of hearing in birds.

Studies of hearing thresholds and frequency- and intensity-difference limens for birds are reviewed. Where possible these are related to limitations placed on auditory function by stimulus processing at peripheral levels of the avian auditory system. The high frequency limit of bird hearing is about 10 kHz; this limit is shown to be imposed in part by middle ear function and in part by cochlear mechanisms. For frequencies greater than 1.0 kHz, frequency-difference limens (DLs) show a similar dependence on frequency in birds as in mammals. Correspondingly, cochlear filtering is shown to be as good in birds as in mammals. At frequency below 1.0 kHz, frequency DLs in birds are poorer than in mammals. These low frequency differences may not be attributable to peripheral processing. Intensity-difference limens are worse in birds than mammals; there seem to be no differences in peripheral processing between birds and mammals which can account for this behavioral difference. Finally, complexities in processing at higher levels of the avian auditory system which have been related to detection of species-specific vocalizations are shown to appear in the first brainstem auditory nuclei.     

Context Specific Signaling with Different Frequencies - Directed to Different Receivers? A Case Study in <Emphasis Type="Italic">Gonatoxia</Emphasis> Katydids (Orthoptera<Emphasis Type="Italic">,</Emphasis> Phaneropteridae)

In katydids (Orthoptera: Tettigonioidea) of the subfamily Phaneropterinae females ready to mate initiate a duet, announcing her position to the male singer, but also potentially to eavesdropping rivals. In many species the male seems to defend the communication by adding self-produced imitations of a female response. If these signals occur within the male sensory time-window after the female song, they can disturb the orientation of rivals. In two species of the genus Gonatoxia, males and females use short, relatively narrow-banded sounds (width 2–7 kHz 10 dB below peak). Male song and female response, however, differ considerably in peak frequency. In G. maculata, the peak frequency of the last part of the male song (13 kHz) is between that of the first part (15 kHz) and the female response (9 kHz), in G. helleri the last part (9 kHz; assumed imitation) and the female song are identical in peak frequency and by a factor two lower than the first part (19 kHz). The male stridulatory file of this species is correspondingly modified and differs from all other members of the genus. The imitation of spectral properties of the female response is not known from any other katydid.     

Use of Ultrasounds to Reduce the Count of Campylobacter coli in Water

The present study aimed to evaluate the effectiveness of low-frequency ultrasounds applied to eliminate Campylobacter spp. from water. The strains used in this research were isolated from water contaminated with sewage. Campylobacter coli alone was detected in the samples and used for further research. The reference strain C. coli ATCC 33559 was simultaneously tested. The isolate was exposed to ultrasounds at frequencies of 37 kHz and 80 kHz in a continuous operation device with ultrapure deionized water. After 5 min of sonication, the count of C. coli decreased by 5.78% (37 kHz) and 6.27% (80 kHz), whereas the temperature increased by 3°C (37 kHz), and 6°C (80 kHz). After 30 min of sonication, the death rates of bacterial cells were 40.15% (37 kHz) and 55.10% (80 kHz), whereas the temperature reached the maximum values of 36°C (37 kHz), and 39°C (80 kHz). Sonication at the frequency of 80 kHz reduced the bacterial count from 6.86 log CFU/ml to 3.08 log CFU/ml, whereas the frequency of 37 kHz reduced the bacterial count from 6.75 log CFU/ml to 4.04 log CFU/ml. Despite significant differences (p < 0.05) in the number of C. coli cells, the cell death rate remained at the same level. Open in a separate window     

Modelling the prey detection performance of Rhinonicteris aurantia (Chiroptera: Hipposideridae) in different atmospheric conditions discounts the notional role of relative humidity in adaptive evolution

We examined a recent notion that differences in echolocation call frequency amongst geographic groups of constant frequency (CF)-emitting bats is the result of a trade-off between maximising prey detection range at lower frequencies and enhancing small-prey resolution at higher frequencies in different atmospheric (relative humidity; RH) environments. Isolated populations of the endemic Australian orange leaf-nosed bat Rhinonicteris aurantia were used as an example since geographic isolation in different environments has been a precursor to differences in their characteristic echolocation call frequencies (mean difference c. 6 kHz; means of 114.64 and 120.99 kHz). The influence of both atmospheric temperature and RH on maximum prey detection range was explored through mathematical modelling. This revealed that temperature was of similar importance to relative humidity and that under certain circumstances, each could reduce the effect of the other on ultrasound attenuation rates. The newly developed models contain significant conceptual improvements in method compared to other recent approaches, and can be applied to the situation of any other species of bat. For a given set of atmospheric conditions, the prey detection range of R. aurantia was reduced slightly when call frequency increased by 6 kHz, but an increase in RH, temperature or both reduced detection range significantly. A similar trend was also evident in prey detection volume ratios calculated for the same conditions. Spatial volume ratios were applied to assess the impact of changed atmospheric conditions and prey size on foraging ecology. Reductions in detection range associated with increases in RH and/or temperature also varied in relation to the size (cross sectional area) of insect prey. Modelling demonstrated that small (6 kHz) movements in call frequency could not compensate for the changes in prey detection range and spatial detection volumes that result from significant changes in atmospheric temperature or RH. The notion that differences in RH are the primary cause leading to adaptive evolution and speciation in CF-emitting bats by precipitating intraspecific differences in the mean call frequency of geographically isolated bat populations was not supported by the results of this case study.     

Directional hearing in the gray tree frog Hyla versicolor: Eardrum vibrations and phonotaxis

1. We used laser vibrometry to study the vibrational frequency response of the eardrum of female gray tree frogs for different positions of the sound source in three-dimensional space. Furthermore, we studied the accuracy of 3-D phonotaxis in the same species for sounds with different frequency contents. 2. The directionality of the eardrum was most pronounced in a narrow frequency range between 1.3 and 1.8 kHz. 3. The average 3-D, horizontal and vertical jump error angles for phonotactic approaches with a sound similar to the natural advertisement call (1.1 and 2.2 kHz frequency components) were 23 degrees, 19 degrees and 12 degrees, respectively. 4. 3-D jump error angle distributions for the 1.4 + 2.2 kHz, 1.0 kHz and 2.0 kHz sounds were not significantly different from that for the 1.1 + 2.2 kHz sound. 5. The average 3-D jump error angle for the 1.4 kHz sound was 36 degrees, and the distribution was significantly different from that for the 1.1 + 2.2 kHz sound. Hence, phonotactic accuracy was poorer in the frequency range of maximum eardrum directionality. 6. Head scanning was not observed and is apparently unnecessary for accurate sound localization in three-dimensional space. 7. Changes in overall sound pressure level experienced by the frog during phonotactic approaches are not an important cue for sound localization.     

Electronic mosquito repellers induce increased biting rates in Aedes aegypti mosquitoes (Diptera: Culicidae)

Studies have demonstrated that electronic mosquito repellers are useless and that some of them could even increase the attraction of mosquitoes. While testing some electronic repellers, we noted that they also promoted an increase in biting rates. The present work has evaluated three commercial devices and a computer program working on five different sound frequencies. In a test chamber, the number of Aedes aegypti L. bite attempts was computed during four cycles of 3 min each by alternately turning the devices off and on. The mosquito biting rates for five sound frequencies (ranging from 9.6 kHz to 18.2 kHz) initially demonstrated a significant increase (ranging from around 20% to 50%), which decreased from 8.3% to 25.1% when the repellers were turned off. The biting rate significantly increased at 11.8 kHz (33.7%) when the device was turned on again. The danger of using electronic repellers and the role of sound frequencies stimulating mosquito biting are discussed.     

Modulation of auditory responsiveness in the locust

The auditory responsiveness of a number of neurones in the meso- and metathoracic ganglia of the locust, Locusta migratoria, was found to change systematically during concomitant wind stimulation. Changes in responsiveness were of three kinds: a suppression of the response to low frequency sound (5 kHz), but an unchanged or increased response to high frequency (12 kHz) sound; an increased response to all sound; a decrease in the excitatory, and an increase in the inhibitory, components of a response to sound. Suppression of the response to low frequency sound was mediated by wind, rather than by the flight motor. Wind stimulation caused an increase in membrane conductance and concomitant depolarization in recorded neurones. Wind stimulation potentiated the spike response to a given depolarizing current, and the spike response to a high frequency sound, by about the same amount. The strongest wind-related input to interneuron 714 was via the metathoracic N6, which carries the axons of auditory receptors from the ear. The EPSP evoked in central neurones by electrical stimulation of metathoracic N6 was suppressed by wind stimulation, and by low frequency (5 kHz), but not high frequency (10 kHz), sound. This suppression disappeared when N6 was cut distally to the stimulating electrodes. Responses to low frequency (5 kHz), rather than high frequency (12 kHz), sounds could be suppressed by a second low frequency tone with an intensity above 50-55 dB SPL for a 5 kHz suppressing tone. Suppression of the electrically-evoked EPSP in neurone 714 was greatest at those sound frequencies represented maximally in the spectrum of the locust's wingbeat. It is concluded that the acoustic components of a wind stimulus are able to mediate both inhibition and excitation in the auditory pathway. By suppressing the responses to low frequency sounds, wind stimulation would effectively shift the frequency-response characteristics of central auditory neurones during flight.     

ABR frequency tuning curves in dolphins

Tone-tone masking was used to determine auditory brain-stem response tuning curves in dolphins (Tursiops truncatus) in a simultaneous-masking paradigm. The Q ₁₀ of the curves was as large as 16–19 in the frequency range 64–128 kHz. In the range 45–16 kHz, Q ₁₀ decreased proportionally to the frequency with the bandwidth of the curves being constant, about 3.5–4 kHz at the 10-dB level. Tuning curves below 45 kHz are supposed to reflect broad spectral bandwidth of the probe's effective part which is no longer than 0.5 ms, irrespective of actual probe duration. Tuning curves above 64 kHz are supposed to reflect the real frequency tuning of the dolphin's auditory system.Abbreviations ABR auditory brain stem response - AP action potential     

Acoustical and neural aspects of hearing in the Australian gleaning bats,Macroderma gigas andNyctophilus gouldi

1. The maximum acoustic gain of the external ear in Macroderma gigas was found to be 25-30 dB between 5-8 kHz and in Nyctophilus gouldi it reached 15-23 dB between 7-22 kHz. Pinna gain reached a peak of 16 dB near 4.5-6 kHz in M. gigas and 12-17 dB between 7-12 kHz in N. gouldi, with average gain of 6-10 dB up to 100 kHz. Pinna gain curves resemble that of a finite conical horn, including resonance. 2. The directional properties of the external ear in both species result from sound diffraction at the pinna face, as it approximates a circular aperture. The frequency dependent movement of the acoustic axis in azimuth and elevation is attributed to the asymmetrical structure of the pinnae. 3. Evoked potentials and neuronal responses were studied in the inferior colliculus. In M. gigas, the neural audiogram has sensitivity peaks at 10-20 kHz and 35-43 kHz, with extremely low thresholds (-18 dB SPL) in the low frequency region. In N. gouldi, the neural audiogram has sensitivity peaks at 8-14 kHz (lowest threshold 5 dB SPL) and 22-45 kHz. Removal of the contralateral pinna causes a frequency dependent loss in neural threshold sensitivity of up to 10-15 dB in both species. 4. The high frequency peak in the audiogram coincides with the sonar energy band in both species, whereas the low frequency region is used for social communication. Highly sensitive low frequency hearing is discussed in relation to hunting in bats by passive listening.     

Binaural influences on Doppler shift compensation of the horseshoe bat Rhinolophus rouxi

The flying horseshoe bat Rhinolophus rouxi compensates for Doppler shifts in echoes of their orientation pulses. By lowering the frequency of subsequent calls the echo's constant frequency is stabilized at the so-called reference frequency centered in a narrow and sensitive cochlear filter. This audio-vocal behaviour is known as Doppler shift compensation. To investigate whether the bats depend on binaural cues when compensating, three animals were tested for compensation on a swing before and after unilateral deafening. In each case compensation was severely impaired by unilateral deafening. Individual animals' compensation amplitude was reduced to 28–48% of the preoperational compensation of a +1.8 kHz shift. Doppler shift compensation performance did not recover to control levels during the observed period of 24 h after surgery. In contrast, unilateral middle ear removal which induces a unilateral auditory threshold increase of 9–14 dB does not impair compensation performance on the swing. To mimick Doppler shifts in a fixed setup, the frequencies of recorded echolocation calls were experimentally shifted between 0 and +2 kHz and played back via earphones to six animals. The bats completely compensated the experimental shifts only as long as the interaural intensity difference of the playback did not exceed 20 dB. No animal compensated with monaural playback. Accepted: 27 August 1999     

Frequency tracking and Doppler shift compensation in response to an artificial CF/FM echolocation sound in the CF/FM bat,Noctilio albiventris

Summary Bats of the speciesNoctilio albiventris emit short-constant frequency/frequency modulated (short-CF/FM) pulses with a CF component frequency at about 75 kHz. Bats sitting on a stationary platform were trained to discriminate target distance by means of echolocation. Loud, free-running artificial pulses, simulating the bat's natural CF/FM echolocation sounds or with systematic modifications in the frequency of the sounds, were presented to the bats during the discrimination trials. When the CF component of the artificial CF/FM sound was between 72 and 77 kHz, the bats shifted the frequency of the CF component of their own echolocation sounds toward that of the artificial pulse, tracking the frequency of the artificial CF component.Bats flying within a large laboratory flight cage were also presented with artificial pulses. Bats in flight lower the frequency of their emitted pulses to compensate for Doppler shifts caused by their own flight speed and systematically shift the frequency of their emitted CF component so that the echo CF frequency returns close to that of the CF component of the artificial CF/FM pulse, over the frequency range where tracking occurs.Abbreviations CF constant frequency - FM frequency modulation     

Multiple specializations in the peripheral auditory system of the CF-FM bat,Pteronotus parnellii

Summary Cochlear microphonic (CM) and evoked neural potentials (N₁) were recorded from the cochlear aqueduct of awakePteronotus parnellii. The CM audiograms obtained with continuous sounds had more or less uniform thresholds except for a sharp threshold notch at about 60 kHz (Fig. 1). When brief tone bursts were presented, the envelopes of the CM responses were always similar to the envelopes of the applied signals except when tone bursts having frequencies at or close to the frequency of the tuned sensitivity notch were presented (i.e., 59–63 kHz). The CM rise-decay times for frequencies around 60kHz were much longer than those of the presented signals (Fig. 2). The prolonged decay times are thought to be due to the ringing of the basilar membrane resulting from a mechanical resonance in the cochlea.The evoked neural potential audiograms (N₁-on and N₁-off responses) differed considerably from the CM audiogram. Of particular importance is the N₁-off audiogram which exhibited very sharp tuning in four frequency regions: 31–33 kHz, 60–63 kHz, 71–73 kHz, and 91–92 kHz (Fig. 5). The frequencies evoking the lowest thresholds of the CM and N₁-off (in the 60 kHz region) were either identical or differed by only 100–400 Hz.The sharp tuning in the 60 kHz region of both the CM and N₁ audiograms could be eliminated by presenting 90–100 dB continuous sounds for one min but only if the signal frequency was equal to the tuned frequency of the CM audiogram (Figs. 8–13). Presenting intense sounds having frequencies above or below the tuned 60kHz region had no effect on the audiogram. The overstimulation procedure had remarkably specific effects on the CM and N₁-off audiograms causing the greatest threshold increases at the 60 kHz tuned frequency and progressively smaller threshold changes on the slopes of the tuned notch.Assuming that the sharp changes of the N₁-off thresholds reflect some important underlying mechanism, the N₁-off audiograms demonstrate multiple specializations in the peripheral auditory system ofPteronotus with the bat possessing at least three and possibly four sharply tuned regions. With regard to mechanism, the tuned notch in the CM audiogram, the curious CM rise-decay times evoked by tone bursts, and the ease with which the 60 kHz sensitivity notch can be eliminated all argue strongly in favor of a mechanical resonance in the cochlea which is responsible for the sharp tuning around 60 kHz. On the other hand, the absence of tuned notches in the 30 kHz and 90 kHz regions of the CM audiogram together with the absence of any discernable ringing of the CM potentials evoked by 30 kHz and 90 kHz tone bursts both argue against a resonance mechanism for the tuning at these harmonically related frequency regions. Finally, the fact that overstimulating the 60 kHz region had no discernable effect on the N₁-off tuning at 30 kHz and 90 kHz demonstrates that the mechanism responsible for the tuned regions at 30 kHz and 90 kHz are independent of the resonance feature of the cochlea at 60 kHz.Abbreviations BF best frequency - CF constant frequency - CM cochlear microphonics - CM-aft after-response of the CM - FM frequency modulated - N ₁ evoked neural potentials We thank Professor Alvin Novick for the generous support provided during the conduct of these experiments. We also thank Professor Gerhard Neuweiler and Dr. Gerd Schuller for their helpful comments and suggestions. Supported by PHS Grant NB7616 11.     

Echoortung bei der Fledermaus Chilonycteris rubiginosa

Zusammenfassung Chilonycteris rubiginosa erzeugt in allen Orientierungsituationen dreiteilige Ortungslaute. Im Anfangsteil steigt die Frequenz um etwa 1–2 kHz an. Der folgende Mittelteil hat eine konstante Frequenz von etwa 57 bis 57,6 kHz. Im Endteil fällt die Frequenz um etwa 8 kHz ab. Die Laute werden in Folgen von Lautgruppen ausgesendet.CR erzeugt pro Flügelschlag eine Lautgruppe. Im freien Flug zeigt CR Gruppen mit 2 Lauten von etwa 17–23 msec Dauer. Landende Fledermäuse senden in der Annäherungsphase Gruppen mit einer zunehmenden Zahl immer kürzerer Laute und in der Schlußphase eine längere Gruppe mit vielen kurzen Lauten.Fliegende Tiere senken die Frequenz des konstantfrequenten Mittelteils immer um etwa den Betrag der durch die Fluggeschwindigkeit bedingten Dopplereffekte ab, so daß die von den Tieren gehörte Echofrequenz nahezu konstant in Höhe der vor dem Flug ausgesendeten Frequenz gehalten wird.CR zeigt Kopf- und Ohrbewegungen. Die Ohrbewegungen stehen in Beziehung zur Lautaussendung.

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Echolocation by the bat Chilonycteris rubiginosa

Summary Chilonycteris rubiginosa (CR) produces tripartite ultrasonic sounds in all orientation situations. During the first part the frequency rises by 1–2 kHz. The following middle part has a constant frequency of about 57–57,6 kHz. In the terminal part the frequency decreases by about 8 kHz. The sounds are emitted as a sequence of groups of sounds.In flight they produce per wingbeat one group of sounds at a repetition rate of 10–11 Hz. In free flight CR emits groups of 2 sounds of about 17–23 msec duration. During the approach landing bats emit groups consisting of an increasing number of sounds of decreasing duration. During the terminal phase the group is longer in duration and consists of many short sounds.Flying CR lower the frequency of the middle part by an amount which compensates for Doppler shifts caused by the flight velocity. The frequency heard by the bats is, thus, always kept constant and equal to a frequency which is about 100–150 Hz above the medium frequency emitted before the flight. CR shows head and ear movements. The ear movements are correlated to the sound emission.

     

Microwave dielectric measurements of erythrocyte suspensions.

Complex dielectric constants of human erythrocyte suspensions over a frequency range from 45 MHz to 26.5 GHz and a temperature range from 5 to 40 degrees C have been determined with the open-ended coaxial probe technique using an automated vector network analyzer (HP 8510). The spectra show two separate major dispersions (beta and gamma) and a much smaller dispersion between them. The two major dispersions are analyzed with a dispersion equation containing two Cole-Cole functions by means of a complex nonlinear least squares technique. The parameters of the equation at different temperatures have been determined. The low frequency behavior of the spectra suggests that the dielectric constant of the cell membrane increases when the temperature is above 35 degrees C. The real part of the dielectric constant at approximately 3.4 GHz remains almost constant when the temperature changes. The dispersion shifts with temperature in the manner of a thermally activated process, and the thermal activation enthalpies for the beta- and gamma-dispersions are 9.87 +/- 0.42 kcal/mol and 4.80 +/- 0.06 kcal/mol, respectively.     

Acoustic irradiation produced by flying moths (Lepidoptera,Noctuidae)

Characteristics of acoustic waves accompanying the flight of noctuid moths (Noctuidae) were measured. The low-frequency part of the spectrum is formed of a series of up to 17 harmonics of the wingbeat frequency (30–50 Hz) with a general tendency toward the decrease in the spectral density and the increase in the sound frequency. The root-mean-square level of the sound pressure from flapping wings was found to be 70–78 dB SPL. Besides low-frequency components, the flight of moths was accompanied by short ultrasonic pulses, which appeared with every wingbeat. Most of the spectral energy was concentrated within a range of 7–150 kHz with the main peaks at 60–110 kHz. The short-term pulses were divided into two or more subpulses with different spectra. The high-frequency pulses were produced at two phases of the wingbeat cycle: during the pronation of the wings at the highest point and at the beginning of their upward movement from the lowest point. In most of the specimens tested, the peak amplitude of sounds varied from 55 to 65 dB SPL at a distance of 6 cm from the insect body. However, in nine noctuid species, no high-frequency acoustic components were recorded. In these experiments, the acoustic flow from the flying moth within a frequency range of 2 to 20 kHz did not exceed the self-noise level of the microphone amplifier (RMS 18 dB SPL). Probable mechanisms of the high frequency acoustic emission during flight, the effect of these sounds on the auditory sensitivity of moths, and the possibility of their self-revealing to insectivorous bats are discussed. In addition, spectral characteristics of the moth echolocation clicks were more precisely determined within the higher frequency range (>100 kHz).