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

Results of Wilcoxon two-sample tests (t approximation) comparing median values of size distributions between regions for all fusulinoidean species and for species within individual families.

<p>Results of Wilcoxon two-sample tests (t approximation) comparing median values of size distributions between regions for all fusulinoidean species and for species within individual families.</p

Intraspecific size differences between regions, illustrated using the largest specimen for each species in each region.

<p>The graph illustrates the tendency for the largest equatorial specimen of a given species to be larger than the largest conspecific specimen from the transitional zones. (A) All species. (B) Ozawainellidae. (C) Staffellidae. (D) Schubertellidae. (E) Schwagerinidae. (F) Neoschwagerinidae. (G) Verbeekinidae. Boxes and whiskers as in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0038603#pone-0038603-g002" target="_blank">Figure 2</a>. * <i>p</i><0.05; ** <i>p</i><0.01; *** <i>p</i><0.001. Significance levels of all comparisons are presented in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0038603#pone-0038603-t002" target="_blank">Table 2</a>.</p

Convergent body size evolution of Crocodyliformes upon entering the aquatic realm (SICB 2018)

Twenty-four species of crocodile populate the globe today, but this richness represents a minute fraction of the diversity and disparity of Crocodyliformes since their origin early in the Triassic. Across this clade, three major diversification events into the aquatic realm occurred. Aquatic and terrestrial habitats impose differing selective pressures on body size. However, previous research on this topic in Crocodyliformes remains qualitative in nature. In this study, our goal was to quantify the influence of habitat (terrestrial versus aquatic) on the evolution of body size in Crocodyliformes. By compiling an extensive body size database of fossil and modern crocs and using phylogenetic comparative methods, we find a history of repeated body size increase and convergence coupled with increases in strength of selection and decreases in variance following shifts to an aquatic lifestyle, suggesting common selective pressures on life in water spanning multiple independent aquatic clades. Lung volume, which has long been proposed as the main constraint on diving time, is only a constraint at sizes greater than 10 kg, whereas the rate of cooling constrains diving time at sizes less than 10 kg. Therefore, we propose this may be the primary driver of larger body sizes in aquatic crocodyliformes

Results of t-tests comparing mean values of within-species size differences between regions to a null hypothesis of no size difference between regions.

<p>Results of t-tests comparing mean values of within-species size differences between regions to a null hypothesis of no size difference between regions.</p

Size distributions of species endemic to indicated regions, using the largest specimen for each species in each region.

<p>(A) All species. (B) Ozawainellidae. (C) Staffellidae. (D) Schubertellidae. (E) Schwagerinidae. (F) Neoschwagerinidae. (G) Verbeekinidae. Boxes and whiskers as in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0038603#pone-0038603-g002" target="_blank">Figure 2</a>. * <i>p</i><0.05; ** <i>p</i><0.01; *** <i>p</i><0.001. Significance levels of all comparisons are presented in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0038603#pone-0038603-t003" target="_blank">Table 3</a>.</p

Size distribution of Middle Permian fusulinoidean species, showing bimodal, left-skewed distribution resulting from differences in size and diversity among families.

<p>(A) All species. (B) Size distributions of families. Boxes present interquartile range, with median indicated by a black line. Whiskers indicate 5^th and 95^th percentiles. Species beyond the 5^th and 95^th percentiles are indicated individually.</p

Middle Permian paleogeographic map showing three realms and blocks containing fusulinoideans in the analysis (base map modified after [<b>68</b>]).

<p>Abbreviations/key: N, north transitional zone; E, equatorial zone; S, south transitional zone; 1, Akiyoshi Terrane; 2, Altaid Belt; 3, Armenia; 4, Baoshan Block; 5, Carnic Alps; 6, Central Iran; 7, Changning-Menglian Belt; 8, Crimea; 9, Darvaz; 10, exotic Karakaya complex in Turkey; 11, Greece; 12, Hida Gaien Belt; 13, Indochina Block; 14, Iraq; 15, Israel; 16, Karakorum; 17, Kitakami Terrane; 18, Kunlun-Qadam Block; 19, Lhasa Block; 20, exotic blocks in New Zealand; 21, north Afghanistan; 22, north Caucasus; 23, north Pamir; 24, northern margin of North China Block; 25, Oman; 26, Qamdo Block; 27, Qiangtang Block; 28, Qinling Belt; 29, Salt Range; 30, Sanandaj-Sirjan zone of Iran; 31, Sibumasu Block; 32, Sicily; 33, Slovenia; 34, south Afghanistan; 35, South China; 36, south Pamir; 37, South Primorye; 38, Tengchong Block; 39, Tethys Himalaya; 40, Transcaucasia; 41, Tunisia; 42, Turkey.</p

Results of Wilcoxon two-sample tests (t approximation) comparing median values of size distributions between regions for species endemic to a single region.

<p>Results of Wilcoxon two-sample tests (t approximation) comparing median values of size distributions between regions for species endemic to a single region.</p

Comparison of size distributions of species between the equatorial region and the north and south transitional zones.

<p>Overall, equatorial species are significantly larger than species from the transitional zones, but the direction and magnitude of size differences between regions varies among families. (A) All species. (B) Ozawainellidae. (C) Staffellidae. (D) Schubertellidae. (E) Schwagerinidae. (F) Neoschwagerinidae. (G) Verbeekinidae. Boxes and whiskers as in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0038603#pone-0038603-g002" target="_blank">Figure 2</a>. * <i>p</i><0.05; ** <i>p</i><0.01; *** <i>p</i><0.001. Significance levels of all comparisons are presented in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0038603#pone-0038603-t001" target="_blank">Table 1</a>.</p