21 research outputs found

    Potential Sources of High Frequency and Biphonic Vocalization in the Dhole (<i>Cuon alpinus</i>)

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    <div><p>Biphonation, i.e. two independent fundamental frequencies in a call spectrum, is a prominent feature of vocal activity in dog-like canids. Dog-like canids can produce a low (f0) and a high (g0) fundamental frequency simultaneously. In contrast, fox-like canids are only capable of producing the low fundamental frequency (f0). Using a comparative anatomical approach for revealing macroscopic structures potentially responsible for canid biphonation, we investigated the vocal anatomy for 4 (1 male, 3 female) captive dholes (<i>Cuon alpinus</i>) and for 2 (1 male, 1 female) wild red fox (<i>Vulpes vulpes</i>). In addition, we analyzed the acoustic structure of vocalizations in the same dholes that served postmortem as specimens for the anatomical investigation. All study dholes produced both high-frequency and biphonic calls. The anatomical reconstructions revealed that the vocal morphologies of the dhole are very similar to those of the red fox. These results suggest that the high-frequency and biphonic calls in dog-like canids can be produced without specific anatomical adaptations of the sound-producing structures. We discuss possible production modes for the high-frequency and biphonic calls involving laryngeal and nasal structures.</p></div

    Nasal and oral calls in mother and young trunk-nosed saiga antelopes, <i>Saiga tatarica</i>

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    <div><p>The trunk-like nose of the saiga antelope <i>Saiga tatarica</i> is a striking example of an exaggerated trait, assumed to having evolved as a dust filter for inhaled air. In addition, it functions to elongate the vocal tract in harem saiga males for producing low-formant calls that serve as a cue to body size for conspecifics. This study applies the sourceā€“filter theory to the acoustics of nasal, oral and nasal-and-oral calls that were recorded from a captive herd of 24 mother and 32 neonate saigas within the first 10 days postpartum. Anatomical measurements of the nasal and oral vocal tracts of two specimens (one per age class) helped to establish the settings for the analysis of formants. In both mother and young, the lower formants of nasal calls/call parts were in agreement with the sourceā€“filter theory, which suggests lower formants for the longer nasal vocal tract than for the shorter oral vocal tract. Similar fundamental frequencies of the nasal and oral parts of nasal-and-oral calls were also in agreement with the sourceā€“filter theory, which postulates the independence of source and filter. However, the fundamental frequency was higher in oral than in nasal calls, probably due to the higher emotional arousal during the production of oral calls. We discuss production mechanisms and the ontogeny of formant patterns of oral and nasal calls among bovid and cervid species with and without a trunk-like nose.</p></div

    Values (meanĀ±SD) of acoustic variables for the cheetah purr inspiration and expiration phases.

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    <p>Values (meanĀ±SD) of acoustic variables for the cheetah purr inspiration and expiration phases.</p

    Call signal-specificity: the percent of 7 call types given in each context, signal-specific calls (i.e., those for which > 65% are given in a single context) are indicated in bold.

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    <p>Call signal-specificity: the percent of 7 call types given in each context, signal-specific calls (i.e., those for which > 65% are given in a single context) are indicated in bold.</p

    Right nasal cavity (A) and its flexible rostral portion (B) of an adult male dhole.

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    <p>(A) Middle nasal concha and nasal septum removed to expose the dorsal, the alar and the basal folds. ** = cut edge of the nasal septum. (B) Detail of (A). The arrow points to the flexible rostral portion of the nose, which can be variably constricted by differential action of the rostral nasal muscles. This will narrow particularly the space between the dorsal and the alar folds and, in concert with movements of the nostril wings, might influence nasal call characteristics. Mediosagittal section of the nasal region, right half, medial view. Scale bar = 10 mm in (A) and (B), respectively.</p

    Intra-pharyngeal ostium in the dhole.

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    <p>During quiet respiration (not panting) and nasal call production the laryngeal entrance protrudes through the intra-pharyngeal ostium into the nasal portion of the pharynx. The intra-pharyngeal ostium is the sole connection between the ventral oral portion and the dorsal nasal portion of the pharynx. Mediosagittal section of pharynx and larynx of an unpreserved specimen, right half, medial view. Scale = 50 mm.</p

    Hyoid apparatus (A) and laryngeal cartilages (B) of the dhole.

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    <p>(A) Excised hyoid apparatus and larynx; overlying muscles partly reconstructed on the basis of macroscopic dissection. The thyrohyoid 'articulation' is established by a cartilaginous connection. (B) Left half of hyoid apparatus and laryngeal cartilages. The interarytenoid cartilage is intercalated between left and right arytenoid cartilage. A sesamoid cartilage supports the transverse arytenoid muscles at their dorsomedian fusion along the transverse furrow between the corniculate and medial processes of the arytenoid cartilages. Colours in (A): green = M. cricopharyngeus; blue = M. thyropharyngeus; red = M. thyrohyoideus; orange = termination of M. sternothyroideus; yellow = termination of M. sternohyoideus. ** in (B): thyrohyoid connection. (A) and (B): Left lateral view. Scale bar = 10 mm, respectively.</p

    Sex and individual discrimination of the cheetah meows.

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    <p>Green bars indicate values of discriminant function analysis and yellow bars indicate random values, calculated with the randomization procedure. Comparisons between observed and random values with permutation tests are shown above the bars.</p

    Spectrogram illustrating the acoustic similarity between the high-frequency squeaks of a dhole (A) and the whistles of a human (B).

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    <p>(A) A natural series of a captive male dhole. (B) A natural series of an adult male zoo visitor, imitating the dhole calls (<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0146330#pone.0146330.s004" target="_blank">S4 Audio</a>). A 5 kHz high-pass filter was applied to remove background noise. Spectrogram settings as in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0146330#pone.0146330.g001" target="_blank">Fig 1</a>.</p
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