Playback Signals Research Articles

Do chewing cues from drywood termites mediate recruiting for wood colonization?

AbstractDrywood termites, Cryptotermes brevis (Walker) (Isoptera: Kalotermitidae), are eusocial insects living and foraging in groups inside pieces of wood, in which they perform a suite of behavioral traits ranging from individual to coordinated group activities. Vibroacoustic cues play important roles in behavioral mediation during defense and foraging activities. However, termite societies also exhibit other relevant behaviors, including substrate selection for colony establishment, which has received little attention. Therefore, we tested the hypothesis that vibrational cues produced by termites inside pieces of drywood influence wood recruiting of conspecifics using dichotomous choice tests. In addition, we assessed whether the choice affects colony success (i.e., termite survival and wood consumption). Two behavioral activities were recognized among drywood termites colonizing wood galleries – walking and chewing. However, only the chewing cues overcome background noise, allowing acoustic signal characterization and playback tests; thus, they were the focus of our study. Overall, drywood termite groups exhibit random choice among wood‐testing unities, indicating that the chewing cues from the natural and/or playback signals are not used as a social trigger to mediate conspecific recruiting for wood preference and colonization. Nonetheless, the establishment of termite colonies in infested vs. non‐infested wood pieces led to better termite performance in the former, exhibiting higher wood consumption and survival.

Substrate-Borne Vibration Mediates Intrasexual Agonism in the New Zealand Cook Strait Giant Weta (Deinacrida rugosa)

Substrate-borne vibrational communication is a common mode of information transfer in many invertebrate groups, with vibration serving as both primary and secondary signal channels in Orthopterans. The Cook Strait giant weta, Deinacrida rugosa (Orthoptera: Anostostomatidae), is an endangered New Zealand insect whose communication system has not been previously described. After field observations of intraspecific interactions in D. rugosa provided preliminary evidence for substrate-borne vibrational communication in the species, we sought to identify the following: vibrational signal structure, the mechanism of signal production, whether signal production is a sexually dimorphic trait, whether substrate-borne signals encode information regarding sender size, the primary social context in which vibration is utilized and finally, the function of vibrational signaling in the species. We used laser Doppler vibrometry to show that D. rugosa males produce low frequency (DF = 37.00 ± 1.63 Hz) substrate-borne vibrations through dorso-ventral tremulation. Rarely produced by females, male signals appear to target rivals while both are in the direct physical presence of a female. Tremulatory responses to playbacks were only produced by males in male-male-female trial contexts, and neither sex exhibited walking vibrotaxis to playback signals, indicating that substrate-borne vibrational signals are not likely a component of the courtship repertoire. While we found that vibrational signal structure was not closely related to signaler size, males that initiated male-male signaling bouts held a significant advantage in contests.

Disembodying the invisible: electrocommunication and social interactions by passive reception of a moving playback signal.

Mormyrid weakly electric fish have a special electrosensory modality that allows them to actively sense their environment and to communicate with conspecifics by emitting sequences of electric signals. Electroreception is mediated by different types of dermal electroreceptor organs for active electrolocation and electrocommunication, respectively. During electrocommunication, mormyrids exhibit stereotyped discharge sequences and locomotor patterns, which can be induced by playback of electric signals. This raises the question: what sensory information is required to initiate and sustain social interactions, and which electrosensory pathway mediates such interactions? By experimentally excluding stimuli from vision and the lateral line system, we show that Mormyrus rume proboscirostris can rely exclusively on its electrosensory system to track a mobile source of electric communication signals. Detection of electric playback signals induced discharge cessations, followed by double-pulse patterns. The animals tried to interact with the moving signal source and synchronized their discharge activity to the playback. These behaviors were absent in control trials without playback. Silencing the electric organ in some fish did not impair their ability to track the signal source. Silenced fish followed on trajectories similar to those obtained from intact animals, indicating that active electrolocation is no precondition for close-range interactions based on electrocommunication. However, some silenced animals changed their strategy when searching for the stationary playback source, which indicates passive sensing. Social interactions among mormyrids can therefore be induced and mediated by passive reception of electric communication signals without the need for perception of the location of the signal source through other senses.

Object discrimination through active electrolocation: Shape recognition and the influence of electrical noise

The weakly electric fish Gnathonemus petersii can recognise objects using active electrolocation. Here, we tested two aspects of object recognition; first whether shape recognition might be influenced by movement of the fish, and second whether object discrimination is affected by the presence of electrical noise from conspecifics. (i) Unlike other object features, such as size or volume, no parameter within a single electrical image has been found that encodes object shape. We investigated whether shape recognition might be facilitated by movement-induced modulations (MIM) of the set of electrical images that are created as a fish swims past an object. Fish were trained to discriminate between pairs of objects that either created similar or dissimilar levels of MIM of the electrical images. As predicted, the fish were able to discriminate between objects up to a longer distance if there was a large difference in MIM between the objects than if there was a small difference. This supports an involvement of MIMs in shape recognition but the use of other cues cannot be excluded. (ii) Electrical noise might impair object recognition if the noise signals overlap with the EODs of an electrolocating fish. To avoid jamming, we predicted that fish might employ pulsing strategies to prevent overlaps. To investigate the influence of electrical noise on discrimination performance, two fish were tested either in the presence of a conspecific or of playback signals and the electric signals were recorded during the experiments. The fish were surprisingly immune to jamming by conspecifics: While the discrimination performance of one fish dropped to chance level when more than 22% of its EODs overlapped with the noise signals, the performance of the other fish was not impaired even when all its EODs overlapped. Neither of the fish changed their pulsing behaviour, suggesting that they did not use any kind of jamming avoidance strategy.

Recording characteristics of high-density thin optical disk using near-field optical recording

We report on the recording characteristics of a near-field optical recording thin optical disk (NFR-TOD). We proposed a new cooling-less-type write strategy for recording, applied it to the NFR-TOD experimental system, and also applied a partial response maximum likelihood (PRML) signal processing, which was evaluated and optimized the PR coefficient for playback signals of the prototype NFR-TOD. The NFR-TOD has a track pitch of 160 nm and improved recording characteristics. The experimental results of the prototype NFR-TOD and the system indicate sufficiently low bit error rates (bERs) for recorded data at a fourfold higher recording density than the current Blu-ray disk.

Jamming avoidance during active electrolocation of objects in the weakly electric fish, Gnathonemus petersii

Event Abstract Back to Event Jamming avoidance during active electrolocation of objects in the weakly electric fish, Gnathonemus petersii Sarah Schumacher1 and Gerhard Von Der Emde1* 1 University of Bonn, Zoology, Germany Gnathonemus petersii is a weakly electric fish, which orients in its environment by detecting changes in a self generated electric field caused by objects. They generate electric signals with an electric organ located in the tail and perceive the resulting electric images with epidermal electroreceptors. During electrolocation G. petersii is able to discriminate between two objects up to a distance of about 4 cm, as shown by previous experiments. In this project we tested whether interfering electric signals from a conspecific influence the effectiveness of object discrimination. Fish were trained to discriminate between two objects in a food-rewarded two-alternative forced-choice procedure while a second fish was present or when a computer generated playback signal was presented. We tested whether the discrimination performance changed under these conditions at object distances of 1 and 3 cm. In addition, we recorded the electric signals of the fish during these experiments and tested whether G. petersii has a certain strategy to avoid jamming by signals from another fish. Our results show that there is no longterm degradation of the performance when a second fish is present. The experiments with playback signals showed no consistent results: The discrimination performance of one fish deteriorated at playback frequencies greater than200 Hz, while another one was not effected even at frequencies of 1.5 kHz. Regarding the recordings of the electrical signals there is no obvious jamming avoidance strategy. The results show that G. petersii is able to discriminate objects in presents of conspecifics without a decrease of effectiveness. Keywords: object discrimination, Orientation, Sensory Perception Conference: Tenth International Congress of Neuroethology, College Park. Maryland USA, United States, 5 Aug - 10 Aug, 2012. Presentation Type: Poster Presentation (see alternatives below as well) Topic: Sensory: Electrosensory Citation: Schumacher S and Von Der Emde G (2012). Jamming avoidance during active electrolocation of objects in the weakly electric fish, Gnathonemus petersii. Conference Abstract: Tenth International Congress of Neuroethology. doi: 10.3389/conf.fnbeh.2012.27.00230 Copyright: The abstracts in this collection have not been subject to any Frontiers peer review or checks, and are not endorsed by Frontiers. They are made available through the Frontiers publishing platform as a service to conference organizers and presenters. The copyright in the individual abstracts is owned by the author of each abstract or his/her employer unless otherwise stated. Each abstract, as well as the collection of abstracts, are published under a Creative Commons CC-BY 4.0 (attribution) licence (https://creativecommons.org/licenses/by/4.0/) and may thus be reproduced, translated, adapted and be the subject of derivative works provided the authors and Frontiers are attributed. For Frontiers’ terms and conditions please see https://www.frontiersin.org/legal/terms-and-conditions. Received: 30 Apr 2012; Published Online: 07 Jul 2012. * Correspondence: Dr. Gerhard Von Der Emde, University of Bonn, Zoology, Bonn, 53115, Germany, vonderemde@uni-bonn.de Login Required This action requires you to be registered with Frontiers and logged in. To register or login click here. Abstract Info Abstract The Authors in Frontiers Sarah Schumacher Gerhard Von Der Emde Google Sarah Schumacher Gerhard Von Der Emde Google Scholar Sarah Schumacher Gerhard Von Der Emde PubMed Sarah Schumacher Gerhard Von Der Emde Related Article in Frontiers Google Scholar PubMed Abstract Close Back to top Javascript is disabled. Please enable Javascript in your browser settings in order to see all the content on this page.

Who is Calling? Intraspecific Call Variation in the Aromobatid Frog Allobates femoralis

AbstractMany territorial species respond less aggressively to familiar neighbours than to unfamiliar floating strangers based on individual differences in acoustic signals. This form of social recognition, termed neighbour–stranger discrimination (NSD) or dear‐enemy phenomenon has been reported so far from three anuran species. To investigate the potential of auditory signal features to convey information on sender’s identity, we determined patterns of within‐male and between‐male variability in the advertisement call of the aromobatid frog Allobates femoralis. We examined 285 calls from 19 males to assess those call properties showing sufficient and reliable inter‐individual differences to function as possible recognition cues. Beside calls per call bout and call rate, all other examined call properties were more variable among males than within males. Generally, temporal call features showed higher between‐ and within‐male variability ratios than spectral properties and contributed mostly to distinguish individual males in the discriminant‐function analysis. Mean classification success of 64.9% correctly assigned calls to individual males is mainly attributable to three temporal call properties (duration of note 1 and 4, note repetition rate). Altogether, our results suggest that there is sufficient variation in the advertisement call to discriminate statistically among individual males. However, assessed call differences between A. femoralis males were rather small, suggesting that potential NSD might be based either on a combination of call features or even on the whole pattern of individual call variation instead on single call properties. Habituation–discrimination experiments in the field using modified playback signals to test for differential behavioural responses are required to confirm this hypothesis.

A scalable spherical microphone array for spatial sound capture

With recent popular consumer acceptance of surround-sound audio, there is the need to develop new technologies that will allow for more accurate sound-field recording commensurate with or exceeding current multichannel audio playback systems. Real-world playback systems can have widely varying geometries and number of channels due to space and aesthetic requirements. Thus, there is a need to have a general recording scheme that allows for computationally simple modifications of the signals to optimize the playback for any geometry and number of playback speakers. One would also like to have a recording system that is scalable for future advances in spatial audio playback technology. A spherical microphone array has been proposed as a solution to these requirements. A spherical array has the desired property of enabling a beam pattern that is steering direction invariant with a relatively simple beamformer structure. The spherical array topology enables scalability and an elegant and mathematically straightforward beamformer design for efficient sampling and processing of the acoustic field. This talk will describe how the spherical array beamformer decomposes the sound field into compact multichannel representations that allow computationally efficient transformations to uniquely tailor the playback signals to any specific playback geometry.

Read channels for prepatterned media with trench playback

Patterned media can be prepared by depositing conventional continuous-film media on prepatterned substrates, such as DVD-like plastic disks. Significant playback signals are produced from media deposited in the substrate trenches, at terabits-per-inch/sup 2/ lithographic feature size limits. Three recording channels are analyzed to deal with these signals - standard symmetric-pulse partial response maximum likelihood (ignoring the trench signal), an asymmetric partial response channel with different positive and negative pulse targets, and simple cancellation of the trench signal. The latter has the best bit-error rate (BER), even with 10% cancellation errors. Perpendicular media without an underlayer had superior BER to horizontal.

Magnetic printing technique for longitudinal thin film media with high coercivity of 6000 Oe

A magnetic printing technique was satisfactorily demonstrated for longitudinal hard-disk media with coercivity of 3000 Oe, in which soft magnetic patterns formed on a master disk as servo signals were magnetically transferred onto the media. The magnetic field (the printing field) applied to the master disk during the printing process is required to be as high as the coercivity of the media, which increases as the areal density of the hard-disk drive increases. However, high printing fields have been reported to cause magnetic saturation of the patterns and extraneous subpulses due to that saturation. This article addresses the issue of whether magnetic printing for media with high coercivity can be satisfactorily carried out. We observed playback signals from printed media with different coercivities ranging up to 6450 Oe and demonstrated that the magnetic printing technique for media with coercivity of up to 6000 Oe was satisfactorily implemented.

Listening in the dark: Behavioral and neural mechanisms of acoustic recognition in a singing fish

Vocalizing species of teleost fish have a simple repertoire of species-typical signals central to their social and reproductive behavior. Male midshipman fish (‘‘the California singing fish’’) acoustically court females using ‘‘hums’’ that are long duration (secs 1h) and spectrally simple. Individual hums exhibit an essentially flat envelope consisting of a low fundamental frequency (90–100 Hz) and several harmonics. By contrast, naturally occurring acoustic beats show envelope modulations: the hums of neighboring males overlap to produce a beat with a difference frequency (0–8 Hz) in which amplitude and phase modulations result from the continual shifting of the two fundamental frequencies. Behavioral playback (phonotaxis) studies show that individual midshipman can use multiple signal parameters including hum duration, gap duration between successive hums, fundamental frequency, and intensity to distinguish hums from each other, while the effectiveness of beats as playback signals depends upon both beat modulation rates and depth of modulation. Neurophysiological evidence shows that auditory neurons in the midshipmans VIIIth nerve and midbrain encode the physical attributes of these signals mainly using spike rate and spike synchronization, mechanisms that we propose contribute to the neural templates adapted for both hum and beat recognition. [Research supported by NIH.]

Vocal control of acoustic information for sonar discriminations by the echolocating bat, Eptesicus fuscus.

This study aimed to determine whether bats using frequency modulated (FM) echolocation signals adapt the features of their vocalizations to the perceptual demands of a particular sonar task. Quantitative measures were obtained from the vocal signals produced by echolocating bats (Eptesicus fuscus) that were trained to perform in two distinct perceptual tasks, echo delay and Doppler-shift discriminations. In both perceptual tasks, the bats learned to discriminate electronically manipulated playback signals of their own echolocation sounds, which simulated echoes from sonar targets. Both tasks utilized a single-channel electronic target simulator and tested the bat's in a two-alternative forced choice procedure. The results of this study demonstrate changes in the features of the FM bats' sonar sounds with echolocation task demands, lending support to the notion that this animal actively controls the echo information that guides its behavior.

A low-complexity and high-speed detection method for high-density d=1 optical recording

We propose a novel bit-detection method which is applicable to high-density optical recording systems which use d=1 runlength-limited codes. The method detects and corrects sign-reversals caused by playback imperfections in the samples of the shortest recorded domains in the sampled playback signal. The new method is very simple computationally, and offers the potential of implementation at very high speeds, since it does not involve bit-recursive operations. Theoretical analysis, simulation results, and application to experimentally derived playback signals demonstrate the performance of the proposed method, which attains acceptable levels over a wide range of recording densities.

Calculation of playback signals from MFM images using transfer functions

Magnetic force microscopy has proven to be a suitable tool for analysis of high-density magnetic recording materials. Comparison of the MFM image of a written signal with the actual read-back signal of the recording system can give valuable insight in the recording properties of both heads and media. In a first order approach one can calculate a `signal’ by plotting the line integral over the track width along the track direction (Glijer et al., IEEE Trans. Magn. 32 (1996) 3557). The method however does not take into account the spatial frequency dependence of the transfer functions of both the MFM and the readback system. For instance the gap width of the head (limiting the high frequency signals) and the finite length of the MFM tip (limiting the sensitivity for low frequencies) are completely disregarded (Porthun et al., J. Magn. Magn. Mater. 182 (1998) 238). This type of problem involving spatial frequencies can be very elegantly solved in the Fourier space. The response of the MFM is described by the force transfer function (FTF) as introduced by (Porthun et al. (J. Magn. Magn. Mater. 182 (1998) 238) and Hug et al. (J. Appl. Phys. 83 (1998) 5609), which describes the relation between the MFM signal and the sample stray field at the height of the tip. From this stray field an `effective surface charge distribution’ can be calculated, by means of the field transfer function (HTF). The same function HTF can be used to calculate the stray field at the height of the head. From this stray field the playback voltage can be calculated, resulting in the playback transfer function (PTF). In order to do this the Karlquist model had to be extended to three dimensions.

Experimental studies of nonlinearities in MR heads

Magnetoresistive (MR) heads have been widely developed for high density digital magnetic recording. The nonlinear MR head response causes nonlinear distortion in the playback signals, and this results in a degradation of system performance. In this work, techniques for identifying the nonlinearity due to the playback process have been developed. Different levels of nonlinear distortion in the playback signals were observed for different head/disk combinations. The behavior of the MR nonlinear distortion as a function of flying height and recording density was also examined.

Micromagnetic studies of microstructual dependence of track edge recording on signal and nonlinearities in longitudinal thin film media

Square wave recording in polycrystalline longitudinal thin films is studied by using micromagnetic simulation. Track edge recording is examined for various media with different microstructural properties. Signals and medium nonlinearities are studied by including the track edge recording. From the simulated magnetization patterns, it is found that media with higher intergranular exchange coupling has larger track edge area. The introduction of random anisotropy field magnitude reduces the track edge area. Media with higher intergranular exchange coupling will also have transition percolation occur at a lower recording density. At high recording densities partial erasure starts at the track edges, which yields a reduced effective track width. Magnetic poles at the track edges cause broadening of the playback signals, resulting in a larger PW/sub 50/ with increased playback track width.

ＶＴＲ用ダイナミックドラム（ＤＤ）制御系の開発

This paper describes a new control system for VCR drums. The system, called the Dynamic Drum (DD) system, has the drum assembly's rotation axis tilted to accurately trace recording tracks for noise-free playback. The tilt angle for each playback speed is coarsely controlled by a rotary encoder; the tilt angle is finely controlled by a detected envelope of playback signals. The 2-step control of the DD enables fast angle determination and high stability even for videotapes recorded on other VCRs. The data for the optimum tilt angle at each playback speed can be saved for coarse tilt angle control.

Performance of maximum likelihood detectors in partial erasure

Partial Erasure is a well known phenomenon whereby closely spaced magnetic transitions in digital saturation recording partially erase each other. The resulting playback signals exhibit nonlinear pattern dependent amplitude losses. This paper defines and analyzes the performance of sequence detectors matched to a partial erasure model, matched to the RLL code d=0 or d=1 constraint, and also matched to the popular inter-symbol interference targets: PR4, EPR4, EEPR4, or EEEPR4. All of the d=0 detectors show losses on the order of -20*log/sub 10/(1-e) dB, where e is the fraction of the magnetic transition amplitudes erased in a di-bit. All of the d=1 detectors exhibit much less loss than the d=0 detectors. The d=1 EEPR4 and EEEPR4 detectors have no distance losses if e<0.2 and 0.37 respectively, even though significant signal energy is lost.

Development of Compact Disk-Write-Once Hybrid Disk

We developed the new hybrid disk which has a read-only area (ROM), that is, a premastered area, and write-once area (WO), where writing is possible. To be compatible with a compact disk (CD), the disk is a single plate and organic dye is used for the recording layer. The disk has high productivity because there is the possibility of spin-coating the organic dye onto not only the WO area but to pits in the ROM area as well. Furthermore, the disk can have multiple ROM and WO areas as the user's option. To satisfy the CD standards a high reflection rate is achieved by means of characterizing the shape of pits in the ROM area and pregrooves in the WO area. The disk yields good CD playback signals after recording.

２時間再生光学式ＭＵＳＥビデオディスク

A doubled disc recording density is used to produce a high definition videodisc with 120 minutes of playback time on both sides. A MUSE video signal and two kinds of PCM sounds are recorded. A narrower track pitch (from 1.6 μm to 1.1 μm) and a lower linear velocity (from 20 m/s to 14 m/s) is used to produce a higher recording density. Improved optical pick-up resolution is achieved by the employment of a visible laser diode with a wavelength of 670 nm and an objective lens with a numerical aperture value of 0.55. Signal parameter examination is used to increase the signal to noise ratio of playback signals. These technologies applied an injection-molded disc with a fine playback image.