Pinna Shape Research Articles

Acoustic analysis of bat eigenears.

The shape diversity in bat pinnae can be explored using principal component analysis. For this purpose, a vector‐space description of the shapes is obtained by transforming the positions on the inner and outer pinna surfaces into cylindrical coordinates. This yields two functions of two independent variables: inner and outer surface radius as a function of angle and height. Pinnae from different species were aligned at the centers of gravity of these functions. The domain of the two functions can be discretized and the corresponding function values arranged to form a vector. In order to explore the acoustic properties of the resulting eigenvectors (“eigenears”), the center of the eigenear coordinate system was positioned at the average pinna, which is similar to an obliquely truncated cone and has a simple beampattern dominated by a single, upward‐pointing mainlobe. The first eigenear is similar in shape to the average ear, subtracting or adding it to the first eigenear results in a wider or narrower cone. In the vicinity of the average ear, this operation will likewise result in a wider or narrower mainlobe. The second eigenear has a symmetry‐breaking effect on both the pinna shape and its beampattern. Higher eigenears will also be explored.

The influence of pinna position on head‐related transfer function

The changes of spectrum of sound at listener ear are one of the major cues for sound source localization. Head Related Transfer‐Function (HRTF) describes the influence of torso, head and pinna on sound spectrum. It is possible to recognize HRTF using computational method, e.g. Boundary Elements Method (BEM). The numerical model used for calculation of HRTF is constructed by transfer geometrical shape of head and pinna into numerical domain. Important question during geometry reconstruction process is the accuracy of shape mapping. The pinna has significant influence on HRFT. In the paper, the influence of accuracy of pinna geometry transformation and pinna position on HRTF is presented. Particularly, the pinna flare angle, pinna rotation angle and position of ear entrance were taking into considerations. Measurements have been done on numerical model with the invariable pinna and head shapes, using BEM method.

Numerical Analysis of the Effects of Pinna Shape and Position on the Characteristics of Head‐Related Transfer Functions

There are distinctive notches and peaks in Head‐Related Transfer Functions (HRTFs). Some of them are considered as important cues in the perception of the elevation angle and thus the roles of these peaks and notches should be clarified. It is known that the characteristics of HRTFs are deeply related to listener's anthropometry. It is thus naturally expected that frequencies of the peaks and notches also change according to the individuality of listeners' anthropometry. Therefore, in this study, effects of ear shapes and positions on frequency positions of the peaks and notches are examined by numerical analyses. The analysis was performed with boundary element method (BEM). A three‐dimensional model of a dummy‐head was constructed with a three‐dimensional laser scanner and HRTFs of the model were numerically computed with a BEM solver. The model was modified on some features as follows: 1) pinna position, 2) pinna size, 3) angle of pinna toward listener's head, and 4) existence of wrinkles of pinna. HRTFs of the modified models were also computed. From the comparison among the results of calculation, several systematic changes were found. For example, the frequency position of notches around 8 kHz is shifted toward lower frequency as the size of pinna increases.

A numerical study of the role of the tragus in the big brown bat

A comprehensive characterization of the spatial sensitivity of an outer ear from a big brown bat (Eptesicus fuscus) has been obtained using numerical methods and visualization techniques. Pinna shape information was acquired through x-ray microtomography. It was used to set up a finite-element model of diffraction from which directivities were predicted by virtue of forward wave-field projections based on a Kirchhoff integral formulation. Digital shape manipulation was used to study the role of the tragus in detailed numerical experiments. The relative position between tragus and pinna aperture was found to control the strength of an extensive asymmetric sidelobe which points in a frequency-dependent direction. An upright tragus position resulted in the strongest sidelobe sensitivity. Using a bootstrap validation paradigm, the results were found to be robust against small perturbations of the finite-element mesh boundaries. Furthermore, it was established that a major aspect of the tragus effect (position dependence) can be studied in a simple shape model, an obliquely truncated horn augmented by a flap representing the tragus. In the simulated wave field around the outer-ear structure, strong correlates of the tragus rotation were identified, which provide a direct link to the underlying physical mechanism.

Modeling HRTF of a thin elastic layered spherical model of head

The understanding and simplified modeling of the Head Related Transfer Function (HRTF) is very important for applications in virtual audio reality. However HRTF depends on many factors such as the shape of head and pinnae, torso, refraction by the body, and others. In this work we investigated the influences of a thin-elastic layered structure of a head on the HRTF. The analytical solution is applied to a six-layer model of the head. The elastic properties of layers are taken into account in the modeling. The results are compared with the results of spherical rigid model and experiments. The numerical results showed the new peaks of HRTF caused by elastic scattering and re-reflecting from layers. However this effect is very small and can be neglected at high frequency.

Unrecorded fern species from Korean flora : Thelypteris interrupta (Thelypteridaceae) and Dryopteris subexaltata (Dryopteridaceae)

Unrecorded fern species of Korean flora, Thelypteris interrupta (Willd.) K. Iwats. (Thelypteridaceae) and Dryopteris subexaltata (H. Christ) C. Chr. (Dryopteridaceae), were collected from Jeju island off the south coast of Korean peninsula and reported here. T. interrupta is most similar to T. acuminata (Houtt.) C. V. Morton in morphology, however, the two species are readily distinguishable by the plant color including rhizome, stipe base and spore, and the presence of glandular hair as well as the distribution pattern of sorus on lower leaf surface. D. subexaltata is also well distinguishable from its relatives, D. sparsa (D. Don) Kuntze, D. sabaei (Franch. & Sav.) C. Chr., and D. yakusilvicola Sa. Kurata by the presence of proliferation, shape of pinnae, distribution pattern of sori on lower leaf surface, and shape of indusium.

A New Species of the Fern Genus Thelypteris (Thelypteridaceae) from Southeastern Brazil

Thelypteris semirii, known only from Minas Gerais, Brazil, is described and illustrated. The new species belongs to Thelypteris subg. Goniopteris, due to the indument of furcate and stellate trichomes on scales, petioles, rachises, and costae. It is most closely related to T scabra (C. Presl) Lellinger (from Argentina, Paraguay, and southeastern Brazil) because of pinna shape, disposition of indument, prominent sinuses, and unbranched trichomes on sporangial stalks. It differs by having trichomes golden or orange, stipitate, and glandular, on both surfaces of all pinnae and indusia. Stems are erect and buds are lacking in the axils of distal pinnae. Besides an early monograph by Christensen (1913) and the surveys of Brade (1972) and Sehnem (1979), nothing more on the taxonomy of the Brazilian species of the Thelypteris subg. Goniopteris (C. Presl) Duek has been published. This subgenus comprises 80 to 100 Neotropical species from Florida, the Antilles, and southern Mexico to northern Argentina and Paraguay (Smith, 1992). Thelypteris subg. Goniopteris is distinguished from other subgenera of Thelypteris by the presence of furcate or stellate trichomes on various plant parts, especially on the scales at the stem apex and in the adaxial groove of the rachis (Smith, 1983). Such trichomes are apparently lacking in a few species of subgenus Goniopteris (Smith, 1983, 1992), but are always present in Brazilian species. The major center of diversity for subgenus Goniopteris is Central America, where 41 species occur. Secondary centers are southeastern Brazil, Peru, and Ecuador. Brazil has approximately 29 species of subgenus Goniopteris, 21 of them occurring in the southeastern part of this country with at least 13 endemic to this region. In southeastern Brazil subgenus Goniopteris grows in mesic and moist shaded habitats, such as primary and secondary lowland and montane rainforests, from 0 to 1000 m, rarely reaching 1600 m. An exception is Thelypteris lugubris (Kunze ex Mettenius) R. Tryon & A. Tryon, which sometimes grows in open woods, along paths and weedy si s such as the understory of banana plantations. The present work provides the description of a new species and a key to the species of Thelypteris subg. Goniopteris of southeastern Brazil most closely related to this new species. Thelypteris semirii Salino & Melo, sp. nov. TYPE: Brazil. Minas Gerais: Marli(ria, Parque Estadual do Rio Doce, Campolina, Dec. 1996, Salino 2848 (holotype, BHCB; isotypes, UC, UEC). Figure 1A-E. Species nova subgeneris Goniopteridis, Thelypteridi scabra (C. Presl) Lellinger affinis, a qua pinnis trichomatibus glandulosis stipitatis abaxialiter vestitis et caule longo erecto differt. Stems erect, with caudex to 15 cm long, scales lanceolate, brownish, with furcate and stellate trichomes, sometimes also with marginal glandular trichomes. Leaves clustered, 64-103 cm long, monomorphic. Petioles yellowish, sulcate on adaxial side, 30-55 x 0.2-0.3 cm, glabrescent to sparsely pilose, with furcate and stellate trichomes up to 1.5 mm long, also with lanceolate scales. Laminae 34-59 cm long, herbaceous to chartaceous, not verrucose, 1-pinnate to pinnatifid, apex gradually reduced, confluent and pinnatifid. Buds and aerophores absent. Rachises densely pilose in adaxial grooves, abaxially sparsely pilose with furcate and stellate trichomes, sometimes also with unbranched trichomes, abaxially sometimes stellate and furcate trichomes absent. Pinnae 11 to 20 pairs per leaf, sessile, 9-12 x 1.3-2 cm, linear-lanceola e, elliptic or lanceolate, with apex acuminate and base truncate or oblique; incised ca. 1/2 their width, with lowermost pinnae strongly deflexed, hair-like scales on abaxial side of costae. Segments 3-6 mm w de, falcate, with margins entire and apex round* Author to whom correspondence should be addressed; salino@mono.icb.ufmg.br NovoN 10: 74-77. 2000. This content downloaded from 157.55.39.121 on Mon, 28 Nov 2016 04:04:15 UTC All use subject to http://about.jstor.org/terms

Immersive audio for desktop systems

Numerous applications are envisioned for integrated media workstations to create, edit, and accurately monitor digital video and audio. There are two major classes of limitations that impede the performance of current desktop loudspeaker-based sound systems. The first encompasses problems that arise due to the local acoustical environment, such as early reflections from the CRT and nearby flat surfaces, as well as the design characteristics and performance of the loudspeakers. The second class involves limitations that arise from variations in human listening characteristics and listener movement relative to the loudspeakers. In this paper several findings are presented that are based on acoustical, psychoacoustical, and signal processing methods for delivering accurate sound field representations. Furthermore, a novel vision-based method for accurate listener tracking is presented that eliminates the need for headgear or tethered magnetic devices. Current findings show that this algorithm can be implemented without imposing a significant computational overhead to the host processor. Research directions include adaptive real-time HRTF synthesis based on the tracking information, as well as vision-based pinna shape classification for improved performance.

Systematics of white‐toothed shrews (Crocidura) (Mammalia: Insectivora: Soricidae) of Taiwan: Karyological and morphological Studies

We define the species boundaries of white‐toothed shrews (genus Crocidura) in Taiwan using karyological and morphological characteristics. Ninety‐nine animals were obtained from all over Taiwan at capture rates usually less than 10%. Three species are recognized by distinct cytotypes: Crocidura attenuata tanakae 2n = 40, FN = 56; Crocidura suaveolens hosletti 2n = 40, FN = 50; Crocidura kurodai 2n = 40, FN = 54. A suite of six morphological characters diagnose the three species: shape of skull, position of incisive foramina, shape of fourth upper premolar, shape of pinna, tail vibrissae, and foot pads. A species key and notes on the life history of each species are provided. Finally, we discuss chromosomal evolution and biolgeography of Crocidura in East and South East Asia.

Auditory spatial resolution in the horizontal plane as a function of reference angle: Microstructure of the azimuth function

Auditory spatial resolution in the horizontal plane was measured in five normal-hearing subjects by determining the minimum audible angle (MAA) for brief 1.0-kHz tones. Using a left–right discrimination paradigm, MAAs were determined for 22 reference azimuths ranging from −62° to +63°. The gross pattern of the mean data was similar to that reported previously for more sparsely sampled azimuth functions: spatial resolution tended to be best when the reference sound was near midline, becoming worse as the reference moved toward the periphery. However, there were remarkable asymmetries and nonmonotonicities in individual subject’s MAA versus azimuth functions, and these nonmonotonic features were highly subject-dependent. Although such individual differences may be due partly to differences among subjects in head and pinna shape, it is possible that the highly individual and idiosyncratic MAA functions also reflect subject-dependent nonmonotonicities in the underlying interaural time difference (ITD) discrimination functions as reference ITD is varied in fine increments. [Work supported by NIH and by the U.S. Army.] a)Current address: ENT/Audiology (HSHJ-SET-A), Madigan Army Med. Ctr., Tacoma, WA 98431-5374.

Sphaerostephanos (Thelypteridaceae) in Asia, excluding Malesia

Sphaerostephanos J. Sm. (in Hook., Gen. Fil. t. 24, 1839) was based on a single species characterized by elongate sori, the structure of which was incorrectly observed, as subsequently noted by its author who later admitted that it is 'scarcely distinct from Nephrodium' (Hist. Fil.: 210, 1875) in which genus, as N. javanicum, it was placed by Hooker (Spec. Fil. 4: 67, 1862). Most subsequent authors, however, maintained it (or its substitute Mesochlaena R. Br.) as a genus solely distinct in its elongate sori; as so constituted it is a mixture of species not closely allied nor sharply distinct from species with circular sori. When I proposed a new system of genera in the family Thelypteridaceae in 1971 (Blumea 19: 39) I found that Sphaerostephanos was the oldest generic name for a large group of mainly Malesian species, most of them with sori not elongate, and re-defined it accordingly. The 17 species in the Pacific were described in 1977 (Allertonia 1, No. 3); the c. 160 species in Malesia will be dealt with in a forthcoming issue of Flora Malesiana Series II; the present paper is concerned with the 13 species of Asia excluding Malesia, six of which are also Malesian in distribution. Nearly all species are plants of forest with erect or short-creeping caudex, and most are of restricted distribution; an exception is the widelydistributed S. unitus which grows in open places and has a long-creeping caudex. A character of almost all species is the presence of small sessile spherical yellow glands which in S. arbuscula occur on both surfaces of pinnae and on indusia and sporangia (Plates 9 & 10). In Malesia a series of species can be traced showing gradual loss of these glands, and there is a considerable minority in which no glands occur, though in other ways they appear to belong to the genus. In mainland Asia S. hirtisorus belongs to this group and appears to be closely allied to the widely-distributed S. invisus (Forst. f.) Holttum of Eastern Malesia and the Pacific. The most distinctive field-character of the genus, which it shares with Pneumatopteris, is the presence of much-reduced basal pinnae, usually with a sharp transition from normal to reduced. The number, size and shape of these reduced pinnae, and the shape of lower normal pinnae, provide important diagnostic characters. Old herbarium specimens often lack the base of fronds, and early authors failed to recognize the distinctive characters of lower pinnae, often also ignoring the presence of glands. This led to

On the Importance of the Individual Shape of Pinnae for the Construction of a Recording Dummy Head

On the Importance of the Individual Shape of Pinnae for the Construction of a Recording Dummy Head