Measurement-Based Automatic Parameterization of a Virtual Acoustic Room Model

Modernien auralisaatiotekniikoiden ansiosta kuulokkeilla voidaan tuottaa kuuntelukokemus, joka muistuttaa useimpien äänitteiden tuotannossa oletettua kaiutinkuuntelua. Huoneakustinen mallinnus on tärkeä osa toimivaa auralisaatiojärjestelmää. Huonemallinnuksen parametrien määrittäminen vaatii kuitenkin ammattitaitoa ja aikaa. Tässä työssä kehitetään järjestelmä parametrien automaattiseksi määrittämiseksi huoneakustisten mittausten perusteella. Parametrisaatio perustuu mikrofoniryhmällä mitattuihin huoneen impulssivasteisiin ja voidaan jakaa kahteen osaan: suoran äänen ja aikaisten heijastusten analyysiin sekä jälkikaiunnan analyysiin. Suorat äänet erotellaan impulssivasteista erilaisia signaalinkäsittelytekniikoita käyttäen ja niitä hyödynnetään heijastuksia etsivässä algoritmissa. Äänilähteet ja heijastuksia vastaavat kuvalähteet paikannetaan saapumisaikaeroon perustuvalla paikannusmenetelmällä ja taajuusriippuvat etenemistien vaikutukset arvioidaan kuvalähdemallissa käyttöä varten. Auralisaation jälkikaiunta on toteutettu takaisinkytkevällä viiveverkostomallilla. Sen parametrisointi vaatii taajuusriippuvan jälkikaiunta-ajan ja jälkikaiunnan taajuusvasteen määrittämistä. Normalisoitua kaikutiheyttä käytetään jälkikaiunnan alkamisajan löytämiseen mittauksista ja simuloidun jälkikaiunnan alkamisajan asettamiseen. Jälkikaiunta-aikojen määrittämisessä hyödynnetään energy decay relief -metodia. Kuuntelukokeiden perusteella automaattinen parametrisaatiojärjestelmä tuottaa parempia tuloksia kuin parametrien asettaminen manuaalisesti huoneen summittaisten geometriatietojen pohjalta. Järjestelmässä on ongelmia erityisesti jälkikaiunnan ekvalisoinnissa, mutta käytettyihin suhteellisen yksinkertaisiin tekniikoihin nähden järjestelmä toimii hyvin.Modern auralization techniques enable making the headphone listening experience similar to the experience of listening with loudspeakers, which is the reproduction method most content is made to be listened with. Room acoustic modeling is an essential part of a plausible auralization system. Specifying the parameters for room modeling requires expertise and time. In this thesis, a system is developed for automatic analysis of the parameters from room acoustic measurements. The parameterization is based on room impulse responses measured with a microphone array and can be divided into two parts: the analysis of the direct sound and early reflections, and the analysis of the late reverberation. The direct sounds are separated from the impulse responses using various signal processing techniques and used in the matching pursuit algorithm to find the reflections in the impulse responses. The sound sources and their reflection images are localized using time difference of arrival -based localization and frequency-dependent propagation path effects are estimated for use in an image source model. The late reverberation of the auralization is implemented using a feedback delay network. Its parameterization requires the analysis of the frequency-dependent reverberation time and frequency response of the late reverberation. Normalized echo density is used to determine the beginning of the late reverberation in the measurements and to set the starting point of the modeled late field. The reverberation times are analyzed using the energy decay relief. A formal listening test shows that the automatic parameterization system outperforms parameters set manually based on approximate geometrical data. Problems remain especially in the precision of the late reverberation equalization but the system works well considering the relative simplicity of the processing methods used

Size-temperature responses of organisms and metabolic response to climate change

<p>The poster was presented at the Gordon Research Conference "A Metabolic Basis of Ecology" in 2012. The work was in prep when presented and explores whether body size responses to increasing temperature can offset temperature effects on metabolic rate.</p

Data Paper. Data Paper

<h2>File List</h2><blockquote> <p>Data files are in ASCII format, tab delimited. No compression schemes were used. Data set consists of 5732 records, not including header row.</p> <p><a href="MOMv3.3.txt">MOMv3.3.txt</a></p> </blockquote><h2>Description</h2><blockquote> <p>The purpose of this data set was to compile body mass information for all mammals on Earth so that we could investigate the patterns of body mass seen across geographic and taxonomic space and evolutionary time.  We were interested in the heritability of body size across taxonomic groups (How conserved is body mass within a genus, family, and order?), in the overall pattern of body mass across continents (Do the moments and other descriptive statistics remain the same across geographic space?), and over evolutionary time (How quickly did body mass patterns iterate on the patterns seen today?  Were the Pleistocene extinctions size specific on each continent, and did these events coincide with the arrival of man?).  These data are also part of a larger project that seeks to integrate body mass patterns across very diverse taxa (NCEAS Working Group on Body size in ecology and paleoecology:  linking pattern and process across space, time and taxonomic scales).  We began with the updated version of Wilson and Reeder’s (1993) taxonomic list of all known Recent mammals of the world (<i>N</i> = 4629 species) to which we added status, distribution, and body mass estimates compiled from the primary and secondary literature. Whenever possible, we used an average of male and female body mass, which was in turn averaged over multiple localities to arrive at our species body mass values.  The sources are line referenced in the main data set, with the actual references appearing in a table within the metadata.  Mammals have individual records for each continent they occur on.  Please note that our data set is more than an amalgamation of smaller compilations.  Although we relied heavily a data set for Chiroptera by K. E. Jones (<i>N</i> = 905), the CRC handbook of Mammalian Body Mass (<i>N</i> = 688), and a data set compiled for South America by P. Marquet (<i>N</i> = 505), these total less than half the records in the current database.  The remainder are derived from more than 150 other sources (see reference table).  Furthermore, we include a comprehensive late Pleistocene species assemblage for Africa, North and South America, and Australia (an additional 230 species). “Late Pleistocene” is defined as approximately 11 ka for Africa, North and South America, and as 50 ka for Australia, because these times predate anthropogenic impacts on mammalian fauna. Estimates contained within this data set represent a generalized species value, averaged across gender and geographic space.  Consequently, these data are not appropriate for asking population-level questions where the integration of body mass with specific environmental conditions is important.  All extant orders of mammals are included, as well as several archaic groups (<i>N</i> = 4859 species).  Because some species are found on more than one continent (particularly Chiroptera), there are 5731 entries.  We have body masses for the following:  Artiodactyla (280 records), Bibymalagasia (2 records), Carnivora (393 records), Cetacea (75 records), Chiroptera (1071 records), Dasyuromorphia (67 records), Dermoptera (3 records), Didelphimorphia (68 records), Diprotodontia (127 records), Hydracoidea (5 records), Insectivora (234 records), Lagomorpha (53 records), Litopterna (2 records), Macroscelidea (14 records), Microbiotheria (1 record), Monotremata (7 records), Notoryctemorphia (1 record), Notoungulata (5 records), Paucituberculata (5 records), Peramelemorphia (24 records), Perissodactyla (47 records), Pholidota (8 records), Primates (276 records), Proboscidea (14 records), Rodentia (1425 records), Scandentia (15 records), Sirenia (6 records), Tubulidentata (1 record), and Xenarthra (75 records).  </p> <p>   <i>Key words</i>: <i>body mass; extinct mammals; late Quaternary; macroecology; taxonomy.</i></p> </blockquote

Supplementary Figures from Hierarchical complexity and the size limits of life

Supplementary Figures S1 - S

Sizes of the Largest Fossils in the Geological Record

This table contains taxonomic, size, and source information describing the largest known fossil plants, animals, protists, and prokaryotes in the fossil record. The prokaryote record covers only the Archaean and early Paleoproterozoic. The protist, animal, and vascular plant records cover all relevant geological periods from the Paleoproterozoic through the Neogene. See also http://bodysize.nescent.org