SciCombinator

Discover the most talked about and latest scientific content & concepts.

Concept: Larynx

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Vocal folds are used as sound sources in various species, but it is unknown how vocal fold morphologies are optimized for different acoustic objectives. Here we identify two main variables affecting range of vocal fold vibration frequency, namely vocal fold elongation and tissue fiber stress. A simple vibrating string model is used to predict fundamental frequency ranges across species of different vocal fold sizes. While average fundamental frequency is predominantly determined by vocal fold length (larynx size), range of fundamental frequency is facilitated by (1) laryngeal muscles that control elongation and by (2) nonlinearity in tissue fiber tension. One adaptation that would increase fundamental frequency range is greater freedom in joint rotation or gliding of two cartilages (thyroid and cricoid), so that vocal fold length change is maximized. Alternatively, tissue layers can develop to bear a disproportionate fiber tension (i.e., a ligament with high density collagen fibers), increasing the fundamental frequency range and thereby vocal versatility. The range of fundamental frequency across species is thus not simply one-dimensional, but can be conceptualized as the dependent variable in a multi-dimensional morphospace. In humans, this could allow for variations that could be clinically important for voice therapy and vocal fold repair. Alternative solutions could also have importance in vocal training for singing and other highly-skilled vocalizations.

Concepts: Acoustics, Human voice, Larynx, Phonation, Vocal folds, Phonetics, Fundamental frequency, Histology of the Vocal Folds

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From complex songs to simple honks, birds produce sounds using a unique vocal organ called the syrinx. Located close to the heart at the tracheobronchial junction, vocal folds or membranes attached to modified mineralized rings vibrate to produce sound. Syringeal components were not thought to commonly enter the fossil record, and the few reported fossilized parts of the syrinx are geologically young (from the Pleistocene and Holocene (approximately 2.5 million years ago to the present)). The only known older syrinx is an Eocene specimen that was not described or illustrated. Data on the relationship between soft tissue structures and syringeal three-dimensional geometry are also exceptionally limited. Here we describe the first remains, to our knowledge, of a fossil syrinx from the Mesozoic Era, which are preserved in three dimensions in a specimen from the Late Cretaceous (approximately 66 to 69 million years ago) of Antarctica. With both cranial and postcranial remains, the new Vegavis iaai specimen is the most complete to be recovered from a part of the radiation of living birds (Aves). Enhanced-contrast X-ray computed tomography (CT) of syrinx structure in twelve extant non-passerine birds, as well as CT imaging of the Vegavis and Eocene syrinxes, informs both the reconstruction of ancestral states in birds and properties of the vocal organ in the extinct species. Fused rings in Vegavis form a well-mineralized pessulus, a derived neognath bird feature, proposed to anchor enlarged vocal folds or labia. Left-right bronchial asymmetry, as seen in Vegavis, is only known in extant birds with two sets of vocal fold sound sources. The new data show the fossilization potential of the avian vocal organ and beg the question why these remains have not been found in other dinosaurs. The lack of other Mesozoic tracheobronchial remains, and the poorly mineralized condition in archosaurian taxa without a syrinx, may indicate that a complex syrinx was a late arising feature in the evolution of birds, well after the origin of flight and respiratory innovations.

Concepts: Evolution, Bird, Larynx, Geology, Cretaceous, Fossil, Paleontology, Dinosaur

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Introduction: The recurrent laryngeal nerve can be injured during surgery. This study investigated recurrent laryngeal nerve reinnervation. Objective: To study the short-term effects of primary anastomosis of the recurrent laryngeal nerve, by laryngeal electromyography and histopathological analysis, in a rabbit model. Method: Twenty Zealand rabbits underwent either right recurrent laryngeal nerve (1) transection with excision of 1 cm or (2) transection and end-to-end primary anastomosis. Vocal fold movements, laryngeal electromyography results and histological changes were recorded. Results: Vocal fold analysis showed a paramedian vocal fold in both groups, with perceptible vibratory movements in group two. Electromyography revealed total denervation potentials in group one, but denervation and regeneration signs in group two. Histopathologically, hyperkeratosis and parakeratosis of the vocal fold mucosa were seen in group one, and signs of parakeratosis and hyperplasia in group two. Conclusion: Even under ideal conditions for primary recurrent laryngeal nerve anastomosis, a return to normal muscle function is unlikely. However, such anastomosis prevents muscle atrophy, and should be performed as soon as possible. The degree of nerve recovery is associated with the number, amplitude and myelination level of fibrils returning to the original motor end-plaque.

Concepts: Surgery, Muscle, Anatomical pathology, Histopathology, Muscle atrophy, Larynx, Recurrent laryngeal nerve, Superior laryngeal nerve

27

Dysphagia is a symptom of swallowing dysfunction that occurs between the mouth and the stomach. Although oropharyngeal dysphagia is a highly prevalent condition (occurring in up to 50% of elderly people and 50% of patients with neurological conditions) and is associated with aspiration, severe nutritional and respiratory complications and even death, most patients are not diagnosed and do not receive any treatment. By contrast, oesophageal dysphagia is less prevalent and less severe, but with better recognized symptoms caused by diseases affecting the enteric nervous system and/or oesophageal muscular layers. Recognition of the clinical relevance and complications of oesophageal and oropharyngeal dysphagia is growing among health-care professionals in many fields. In addition, the emergence of new methods to screen and assess swallow function at both the oropharynx and oesophagus, and marked advances in understanding the pathophysiology of these conditions, is paving the way for a new era of intensive research and active therapeutic strategies for affected patients. Indeed, a unified field of deglutology is developing, with new professional profiles to cover the needs of all patients with dysphagia in a nonfragmented way.

Concepts: Disease, Muscle, Stomach, Larynx, Esophagus, Dysphagia, Swallowing, Oropharyngeal dysphagia

27

The present study aims to evaluate the degree of anterior-posterior and medial supraglottic laryngeal compression in healthy singers of different voice classifications while singing different pitches, loudness, and phonatory tasks.

Concepts: Human voice, Larynx, Singing, Opera, Vocal range, Head voice, Chest voice, Whistle register

25

Background: Iranian vibrato (tahrir) is a common feature of traditional Iranian singing. A unique feature of tahrir is a modulated voice quality perceived as a rhythmic falsetto voice break associated with upward pitch inflections. Laryngeal discomfort and impaired voice quality can occur in singers when they perform Iranian tahrir using an improper technique. Aim: A case series research design was used to explore voice treatment outcomes using laryngeal manual therapy (LMT) for treating voice problems associated with tahrir singing. Method: Four professional Iranian singers of the traditional style (3 men and 1 woman) were studied. All subjects reported difficulty executing tahrir during performances. They were assessed by a speech-language pathologist (SLP) specializing in the administration of LMT for voice disorders. Multidimensional assessments were made of the participants' vocal function using acoustic and auditory-perceptual evaluation, self-reports of the singers, and LMT assessments by the SLP before and after treatment. The therapeutic program implemented LMT techniques to release laryngeal joints and reduce muscular tension. Results: Pretreatment examination of the larynx and anterior neck musculature using palpation showed that the difficulties in producing tahrir vibrato were associated with a decreased thyrohyoid space and tension in the submental complex and sternocleidomastoid. Posttreatment examination showed an increased thyrohyoid space and reduced tension in the submental complex and sternocleidomastoid, associated with the singers' perception of reduced effort producing tahrir vibrato during singing. Conclusion: Tahrir vibrato requires specific training to prevent excessive tension in laryngeal and neck muscles. In the absence of such training, or in the context of excessive singing associated with fatigue, LMT may facilitate more efficient vocal production in tahrir singers. © 2015 S. Karger AG, Basel.

Concepts: Muscle, Human voice, Larynx, Phonation, Vocal folds, Singing, Vocal range, Chest voice

25

The purpose of this work was to study the efficacy of early voice therapy in the management of patients with unilateral vocal fold paralysis.

Concepts: Human voice, Larynx, Phonation, Vocal folds, Phonetics, Singing, Vocal range, Histology of the Vocal Folds

20

Blue whale sound production has been thought to occur by Helmholtz resonance via air flowing from the lungs into the upper respiratory spaces. This implies that the frequency of blue whale vocalizations might be directly proportional to the size of their sound-producing organs. Here we present a sound production mechanism where the fundamental and overtone frequencies of blue whale B calls can be well modeled using a series of short-duration (<1 s) wavelets. We propose that the likely source of these wavelets are pneumatic pulses caused by opening and closing of respiratory valves during air recirculation between the lungs and laryngeal sac. This vocal production model is similar to those proposed for humpback whales, where valve open/closure and vocal fold oscillation is passively driven by airflow between the lungs and upper respiratory spaces, and implies call frequencies could be actively changed by the animal to center fundamental tones at different frequency bands during the call series.

Concepts: Acoustics, Larynx, Frequency, Sound, Radio, Whale, Humpback whale, Whale song

18

Rodent ultrasonic vocalizations (USVs) are a vital tool for linking gene mutations to behavior in mouse models of communication disorders, such as autism [1]. However, we currently lack an understanding of how physiological and physical mechanisms combine to generate acoustic features of the vocalizations, and thus cannot meaningfully relate those features to experimental treatments. Here we test and provide evidence against the two leading hypotheses explaining USV production: superficial vocal fold vibrations [2], and a hole-tone whistle [3]. Instead, we propose and provide theoretical and experimental evidence for an alternative and novel vocal production mechanism: a glottal jet impinging onto the laryngeal inner planar wall. Our data provide a framework for future research on the neuromuscular control of mouse vocal production and for interpreting mouse vocal behavior phenotypes.

Concepts: Scientific method, Gene, Larynx, Phonation, Theory, Rodent, Mouse, Mice

17

Dynamic MRI analysis of phonation has gathered interest in voice and speech physiology. However, there are limited data addressing the extent to which articulation is dependent on loudness.

Concepts: Human voice, Larynx, Phonation, Singing, Vocal range, Head voice, Chest voice, Whistle register