Harvey, Michael J.

Kennedy, Michael L.

McDaniel, V. Rick

English

ScholarWorks@UARK

Journal of the Arkansas Academy of ScienceVolume 32 Article 311978Status of the Endangered Ozark Big-eared Bat(Plecotus townsendii ingens) in ArkansasMichael J. HarveyMemphis State UniversityMichael L. KennedyMemphis State UniversityV. Rick McDanielArkansas State UniversityFollow this and additional works at: http://scholarworks.uark.edu/jaasPart of the Population Biology CommonsThis article is available for use under the Creative Commons license: Attribution-NoDerivatives 4.0 International (CC BY-ND 4.0). Users are able toread, download, copy, print, distribute, search, link to the full texts of these articles, or use them for any other lawful purpose, without asking priorpermission from the publisher or the author.This General Note is brought to you for free and open access by ScholarWorks@UARK. It has been accepted for inclusion in Journal of the ArkansasAcademy of Science by an authorized editor of ScholarWorks@UARK. For more information, please contact scholar@uark.edu, ccmiddle@uark.edu.Recommended CitationHarvey, Michael J.; Kennedy, Michael L.; and McDaniel, V. Rick (1978) "Status of the Endangered Ozark Big-eared Bat (Plecotustownsendii ingens) in Arkansas," Journal of the Arkansas Academy of Science: Vol. 32 , Article 31.Available at: http://scholarworks.uark.edu/jaas/vol32/iss1/31Arkansas Academy of Science Proceedings, Vol. XXXII,1978 89Arkansas Academy of ScienceLITERATURE CITEDALLURED. R. A. 1976. Effect of intensive N and K fertilization ongrowth and persistence ofCoastal Bermudagrass and on the soilchemical environment. M. S. Thesis. University of Arkansas.Favetteville, Ark.BUCHANAN.G. A..C. S. HOVELAND.and M.C. HARRIS. 1975.Response of weeds to soil pH. Weed Science. 23(6):473-477.GEIGY WEED TABLES. 1968. CIBA-GEIGY Chemical Co.. Basle.Switzerland.MEIJDEN. E. VANDER. 1974. The distribution ofSenecio iacohas-al L.and Tyria jacnhaeae L. inrelation to soil properties. ActaBotanica Neerlandica. 23(5-6):681-690.ALLURED. R. A.,E. C. GORDON. L.F.THOMPSON, and R. E.FRANS. 1974. Residual effects of N-K fertilization of CoastalBermudagrass on spring populations of weed species. Arkansa..Academy ofScience Proceedings. 28:9-1 1.NAGEL. D.H. 1977. Yield and elemental content of forage, and soilprofile chemistry, as affected by NH.NO,, KC1, and CaCO, ad-ditions to an established Coastal Bermudagrass sod. M.S. Thesis.University ofArkansas. Favetteville. Ark.BKARD. J. B. 1973. Turfgrass: Science and CULTURE. PrenticeHall. Inc.. Anglewood Cliffs,NJ. pp. 32.S. 339. 381. 408. 414.H. C. FULCHF.R and L.F. THOMPSON. Department of Agronomy. Vniversitv ofArkansas. Favetteville. Arkansas 72701.STATUS OF THE ENDANGERED OZARK BIG-EARED BAT (Plecotus townsendii ingens) IN ARKANSASThree bat taxa endemic to Arkansas are now considered to be endangered (in danger of extinction throughout all or a significant portion oftheir range). The Indiana bat. Myotissodalis. and the gray bat, M. grisescens. are currently on the United States list of endangered species. TheOzark big-eared bat. Plecotus townsendii ingens. (along withthe Virginia big-eared bat, P. I. virginianus) willbe added pending finallegislation.The Ozark big-eared bat has been reported in small numbers from onlya few caves innorthwestern and north central Arkansas, southwest-ern Missouri, and eastern Oklahoma (U. S. Department of the Interior, Fish and Wildlife Service 1973; Handley 1959; Harvey 1975, 1976, 1978;McDaniel and Gardner 1977; Sealander 1951. 1956: Sealanderand Young 1955). The Department of the Interior. Fish and Wildlife Service (1973)estimated the total number surviving tobe less than 100 and stated that never more than four individuals had ever been found at one time. That in-formation is incorrect. Sealander (1951) reported collecting 11 individuals froma Washington County, Arkansas, cave in1951. Itwas notuntil24years later that a number greater than 11 was reported. Harvey (1975. 1976) reported finding 60P. t. ingens in a western Arkansas cave inFebru-ary, 1975.Due to the small number known, relativity little information is available concerning this particular subspecies. However, much isknownabout the species in other parts ofits range, most of which may also apply to P. t. ingens. Humphrey and Kunz(1976) published a detailed accountconcerning the ecology of the southern Great Plains population ofP. townsendii. considered to be an intergrade ofP. t. pallescens of the southernRocky Mountains and P. t. ingens. In addition, several authors have reported on the biology of the more abundant western subspecies (Handley1959; Barbourand Davis 1969; Graham 1966;Dalquest 1974: Pearson et al. 1952; Twente 1955).Inthe eastern part of their range P. townsendii inhabit caves during both summer and winter, although occasional individuals have been ob-served in buildings during the summer. Inthe western part of their range they are often found in buildings. P. townsendii hibernate in caves ormines where the temperature is 12° C or less, but generally above freezing. They are usually found clustered in groups ofa few to a hundred ormore individuals. The species is veryintolerant of human disturbance and willsometimes vacate a cave ifdisturbed (Humphrey 1969; Humphreyand Kunz 1976; Twente 1955; Barbour and Davis 1969).During the past 5years numerous caves innorthwestern and north central Arkansas were searched in an attempt to locate colonies ofOzarkbig-eared (as well as other) bats. Name, location, and a brief description of each cave, as well as a record of bat taxa and numbers present, wererecorded. Collection of specimens was minimal and usually bats were handled onlyifnecessary for identification purposes. Ecological data suchas temperature and humidityof bat microhabitats were recorded. During warmer seasons limited mist netting was conducted in a variety of habi-tat types.The colony of 60P. t. ingens reported by Harvey (1975, 1976) froma western Arkansas cave inFebruary, 1975, was not present in the cavewhen checked during the followingwinter. However, inearly March, 1978, we discovered a cluster of35 hibernating P. t. ingens inanother cave intsame general area. Both caves are in Washington County. InNovember, 1974, we found eight /'. t. ingens clustered above a guano pile in aionCounty cave. Twoskeletons of this bat were found in the guano. An additional Ozark big-eared bat was found ina Marion County mine inruary. 1974.IAlthough numerous other caves and mines innorthwestern and north central Arkansas were searched, no additional P. I. ingens were dis-red. Summer mist netting also failed toresult in the capture of Ozark big-eared bats. However, netting was not done in areas near caves ands from whichP. t. ingens have been reported.tOur records indicate that P. t. ingens prefer relatively cold areas of caves for hibernation. Temperatures where Ozark big-eared bats werend ranged from4° C to 9° C: humidity was 85-95%. We know nothing concerning summer habitat of this taxon. Quite likelynursery coloniesit somewhere in Ozark caves, but thus far none have been found.KThe discovery in the last few years ofgroups ofP. t. ingens numbering from eight to 60 individuals indicates that these bats may be presentreater numbers than previously thought. However, the total surviving population may number no more than a few hundred individuals. Theirct status is still relatively unknown. Known colonies will be monitored and attempts willbe made to locate additional colonies as well as toidentify critical habitat requirements for this taxon. Because no cave regularly inhabited by P. t. ingens has been discovered, no critical habitathas as yet been proposed.Numerous individuals have been involvedin our attempts to ascertain the status of the endangered Ozark big-eared bat in Arkansas. Person-»of the Arkansas Game and Fish Commission. Arkansas Department of Parks and Tourism, U. S. Forest Service, and National Park Servicee supplied information and otherwise aided inmany ways. A number of graduate students and faculty members were involved in field work,sincerely appreciate the efforts of all those who contributed their time and expertise.LITERATURE CITEDBARBOUR. R. W.. and W. H.DAVIS. 1969. Bats ofAmerica. Univ. DALQUEST. W. W. 1947. Notes on the natural historv of the batPress ofKentucky. Lexington. 286 p. Corynorhinus rafinesquii inCalifornia. J. Mammal. 28:17-30.89Journal of the Arkansas Academy of Science, Vol. 32 [1978], Art. 31Published by Arkansas Academy of Science, 19781General NotesGRAHAM,R.E. 1966. Observations on the roosting habits of thebig-eared bat. Plecotus townsendii. in California limestonecaves. Cave Notes 8:17-22.HANDLEY. C. O.. JR. 1959. A revision of American bats of thegenera Euderma and Plecoius. Proc. U. S. Nat. Mus. 110:95-246.HARVEY. M. J. 1975. Endangered Chiroptera of the southeasternUnited States. Proc. 29th Annu. Conf. S. E. Assoc. Game andFish Comm. 29:429-433.HARVEY. M. J. 1976. Status of endangered bats in the easternUnited States. Proc. 1976 Nat. Speleol. Soc. Annu. Convention1976:21-24.HARVEY. M. J. 1978. Ozark big-eared bat. InH. O.Hillestad. ed.Endangered and threatened vertebrates of the southeast. TallTimbers Res. Sta. Bull. Inpress.HUMPHREY. S. R. 1969. Disturbances and bats. Oklahoma Under-ground 2:42-44.HUMPHREY. S. R.. and T. H.KUNZ. 1976. Ecology of a Pleisto-cene relict, the western big-eared bat (Plecoius townsendii), inthe southern Great Plains. J. Mammal. 57:470-494.McDANIEL. V.R.. and J. E. GARDNER. 1977. Cave fauna of Ar- Ikansas: vertebrate taxa. Arkansas Acad. Sci.Proc. 31:68-71.PEARSON. O.P.. M.R. KOFORD. and A.K.PEARSON. 1952. Re- Iproduction of the lump-nosed bat (Corynorhinus rafinesquii) in \California J. Mammal. 33:273-320.SEALANDER. J. A.. JR. 1951. Lump-nosed bat in Arkansas. ].Mammal. 32:465.SEALANDER, J. A.. JR.. and H.YOUNG. 1955. Preliminary obser-vations on the cave bats ofArkansas. Arkansas Acad. Sci. Proc7:21-31.SEALANDER. J. A.. JR. 1956. A provisional check-list and key tothe mammals of Arkansas (with annotations). Amer. Midi.Natur. 56:257-296.TWENTE. J. W. 1955. Aspects of a population study of cavern-dwellingbats. J. Mammal. 36:379-390.U. S. DEPARTMENT OF THE INTERIOR. FISH ANDWILDLIFESERVICE. 1973. Threatened wildlife of the United States. U. S.Dep. Interior. Resource Pub. 114. 280 p. -MICHAELJ. HARVEY. MICHAELL. KENNEDY,and V.RICK McDANIEL.Ecological Research Center. Department of Biologv. MemphisStale University. Memphis. Tennessee 3HI52. and Division ofBiologicalScience. Arkansas Slate University. State Universiiv. Arkansas 72467.THE DESIGN AND CONSTRUCTION OF AN INEXPENSIVE ANECHOIC CHAMBERWhen any degree of precision is needed in obtaining data on the radiation properties ofan acoustical device such as a loudspeaker or musi-cal instrument, measurements are usually taken under free space conditions without the presence of complicating stationary save patterns.Indoor free space measurements require an anechoic room, a room withcompletely sound absorbing walls. However, a specially designed cham-ber can be used as a good approximation ofan anechoic room. •Aportable chamber, as detailed inFigures 1 and 2. can be utilized as an anechoic chamber. Innever having any opposite wall face parallel toanother, stationary wave patterns willbe prevented from establishing themselves. This, combined with the greatly increased surface area due to Vapproximately thirty-fivehundred polyurethane wedges, willgive the central area of the chamber an anechoic effect. Transmitted noise from out-side the chamber is prevented by insulating the chamber withrock wool fiberglass and acoustical ceiling tile.The walls of the chamber consist of four layers. The outer external layer consisting of three-quarter inch plywood, and. although its primarypurpose is that of the skeleton of the chamber, italso serves as the first barrier against external noise. The second layer consist of two inches ofrock wool fiberglass insulation, acting as an acoustical absorber of any noise which is able to penetrate the external layer. The third layer, three-quarter inch acoustical ceiling tile, provides three functions: acting as a final barrier to incident noise from the outside, providing a base fromwhich the polyurethane foam can be attached, and absorbing sound generated from the inside of the chamber. The inner layer is a polyurethanefoam forming a mosaic of alternating vertical and horizontal wedges projected normally from each surface. Each foam wedge is four squareinches at its base and projects four inches toward the central area of the chamber.The chamber is constructed in two equal parts, allowingfor greater mobility,and joined witha latched tongue and groove joint.Steel mesh -.serves to support equipment placed in the chamber. Quarter-inch holes packed with insulation are placed on either end of the chamber givingaccess formicrophone leads orany other test equipment leads.While this chamber will not replace a complete fullsize anechoic room, it willallow for acceptable measurements of acoustical radiation.However, certain limitations are inherent in the dimensions of the chamber. Frequencies lower than 1000 Hz are ofsufficient wavelength to causeconcern. Any application of the chamber should be restricted to making measurements of radiation above the 1000 Hz limit.Measurements ofhigh frequency resonance response characteristics of string instruments, frequency response of loudspeakers, or frequency characteristics ofmicrophones are but a few of the applications of the chamber.This chamber was constructed using funds from a grant made possible by the Bendix Corporation through the Society ofPhysics Students.?Figure l(a). End view of chamber showing cut out view of the insideand the locations of: (It- latches. (2) - polyurethane foam wedges.(3)- 3/> inch acoustical ceiling tile. (4)- 2 inches rock woolinsulation.(5)- V4 inch plywood.Figure lib).Side view of chamber showing placement ofa lest objectsupported by wire mesh.90 Arkansas Academy of Science Proceedings, Vol.XXXII,1978J90Journal of the Arkansas Academy of Science, Vol. 32 [1978], Art. 31http://scholarworks.uark.edu/jaas/vol32/iss1/31

Status of the Endangered Ozark Big-eared Bat (Plecotus townsendii ingens) in Arkansas

UARK (University of Arkansas )

Journal of the Arkansas Academy of Science Volume 32 Article 31 1978 Status of the Endangered Ozark Big-eared Bat (Plecotus townsendii ingens) in Arkansas Michael J. Harvey Memphis State University Michael L. Kennedy Memphis State University V. Rick McDaniel Arkansas State University Follow this and additional works at: https://scholarworks.uark.edu/jaas  Part of the Population Biology Commons Recommended Citation Harvey, Michael J.; Kennedy, Michael L.; and McDaniel, V. Rick (1978) "Status of the Endangered Ozark Big-eared Bat (Plecotus townsendii ingens) in Arkansas," Journal of the Arkansas Academy of Science: Vol. 32 , Article 31. Available at: https://scholarworks.uark.edu/jaas/vol32/iss1/31 This article is available for use under the Creative Commons license: Attribution-NoDerivatives 4.0 International (CC BY-ND 4.0). Users are able to read, download, copy, print, distribute, search, link to the full texts of these articles, or use them for any other lawful purpose, without asking prior permission from the publisher or the author. This General Note is brought to you for free and open access by ScholarWorks@UARK. It has been accepted for inclusion in Journal of the Arkansas Academy of Science by an authorized editor of ScholarWorks@UARK. For more information, please contact scholar@uark.edu. Arkansas Academy of Science Proceedings, Vol. XXXII,1978 89Arkansas Academy of ScienceLITERATURE CITEDALLURED. R. A. 1976. Effect of intensive N and K fertilization ongrowth and persistence ofCoastal Bermudagrass and on the soilchemical environment. M. S. Thesis. University of Arkansas.Favetteville, Ark.BUCHANAN.G. A..C. S. HOVELAND.and M.C. HARRIS. 1975.Response of weeds to soil pH. Weed Science. 23(6):473-477.GEIGY WEED TABLES. 1968. CIBA-GEIGY Chemical Co.. Basle.Switzerland.MEIJDEN. E. VANDER. 1974. The distribution ofSenecio iacohas-al L.and Tyria jacnhaeae L. inrelation to soil properties. ActaBotanica Neerlandica. 23(5-6):681-690.ALLURED. R. A.,E. C. GORDON. L.F.THOMPSON, and R. E.FRANS. 1974. Residual effects of N-K fertilization of CoastalBermudagrass on spring populations of weed species. Arkansa..Academy ofScience Proceedings. 28:9-1 1. NAGEL. D.H. 1977. Yield and elemental content of forage, and soilprofile chemistry, as affected by NH.NO,, KC1, and CaCO, ad-ditions to an established Coastal Bermudagrass sod. M.S. Thesis.University ofArkansas. Favetteville. Ark.BKARD. J. B. 1973. Turfgrass: Science and CULTURE. PrenticeHall. Inc.. Anglewood Cliffs,NJ. pp. 32.S. 339. 381. 408. 414.H. C. FULCHF.R and L.F. THOMPSON. Department of Agronomy. Vniversitv ofArkansas. Favetteville. Arkansas 72701.STATUS OF THE ENDANGERED OZARK BIG-EARED BAT (Plecotus townsendii ingens) IN ARKANSASThree bat taxa endemic to Arkansas are now considered to be endangered (in danger of extinction throughout all or a significant portion oftheir range). The Indiana bat. Myotissodalis. and the gray bat, M. grisescens. are currently on the United States list of endangered species. TheOzark big-eared bat. Plecotus townsendii ingens. (along withthe Virginia big-eared bat, P. I. virginianus) willbe added pending finallegislation.The Ozark big-eared bat has been reported in small numbers from onlya few caves innorthwestern and north central Arkansas, southwest-ern Missouri, and eastern Oklahoma (U. S. Department of the Interior, Fish and Wildlife Service 1973; Handley 1959; Harvey 1975, 1976, 1978;McDaniel and Gardner 1977; Sealander 1951. 1956: Sealanderand Young 1955). The Department of the Interior. Fish and Wildlife Service (1973)estimated the total number surviving tobe less than 100 and stated that never more than four individuals had ever been found at one time. That in-formation is incorrect. Sealander (1951) reported collecting 11 individuals froma Washington County, Arkansas, cave in1951. Itwas notuntil24years later that a number greater than 11 was reported. Harvey (1975. 1976) reported finding 60P. t. ingens in a western Arkansas cave inFebru-ary, 1975.Due to the small number known, relativity little information is available concerning this particular subspecies. However, much isknownabout the species in other parts ofits range, most of which may also apply to P. t. ingens. Humphrey and Kunz(1976) published a detailed accountconcerning the ecology of the southern Great Plains population ofP. townsendii. considered to be an intergrade ofP. t. pallescens of the southernRocky Mountains and P. t. ingens. In addition, several authors have reported on the biology of the more abundant western subspecies (Handley1959; Barbourand Davis 1969; Graham 1966;Dalquest 1974: Pearson et al. 1952; Twente 1955).Inthe eastern part of their range P. townsendii inhabit caves during both summer and winter, although occasional individuals have been ob-served in buildings during the summer. Inthe western part of their range they are often found in buildings. P. townsendii hibernate in caves ormines where the temperature is 12° C or less, but generally above freezing. They are usually found clustered in groups ofa few to a hundred ormore individuals. The species is veryintolerant of human disturbance and willsometimes vacate a cave ifdisturbed (Humphrey 1969; Humphreyand Kunz 1976; Twente 1955; Barbour and Davis 1969).During the past 5years numerous caves innorthwestern and north central Arkansas were searched in an attempt to locate colonies ofOzarkbig-eared (as well as other) bats. Name, location, and a brief description of each cave, as well as a record of bat taxa and numbers present, wererecorded. Collection of specimens was minimal and usually bats were handled onlyifnecessary for identification purposes. Ecological data suchas temperature and humidityof bat microhabitats were recorded. During warmer seasons limited mist netting was conducted in a variety of habi-tat types.The colony of 60P. t. ingens reported by Harvey (1975, 1976) froma western Arkansas cave inFebruary, 1975, was not present in the cavewhen checked during the followingwinter. However, inearly March, 1978, we discovered a cluster of35 hibernating P. t. ingens inanother cave intsame general area. Both caves are in Washington County. InNovember, 1974, we found eight /'. t. ingens clustered above a guano pile in aionCounty cave. Twoskeletons of this bat were found in the guano. An additional Ozark big-eared bat was found ina Marion County mine inruary. 1974.IAlthough numerous other caves and mines innorthwestern and north central Arkansas weresearched, no additional P. I. ingens were dis-red. Summer mist netting also failed toresult in the capture of Ozark big-eared bats. However, netting was not done in areas near caves ands from whichP. t. ingens have been reported.tOur records indicate that P. t. ingens prefer relatively cold areas of caves forhibernation. Temperatures where Ozark big-eared bats werend ranged from4° C to 9° C: humidity was 85-95%. We know nothing concerning summer habitat of this taxon. Quite likelynursery coloniesit somewhere in Ozark caves, but thus far none have been found.KThe discovery in the last few years ofgroups ofP. t. ingens numbering from eight to 60 individuals indicates that these bats may be presentreater numbers than previously thought. However, the total surviving population may number no more than a few hundred individuals. Theirct status is still relatively unknown. Known colonies will be monitored and attempts willbe made to locate additional colonies as well as toidentify critical habitat requirements for this taxon. Because no cave regularly inhabited by P. t. ingens has been discovered, no critical habitathas as yet been proposed.Numerous individuals have been involvedin our attempts to ascertain the status of the endangered Ozark big-eared bat in Arkansas. Person-»of the Arkansas Game and Fish Commission. Arkansas Department of Parks and Tourism, U. S. ForestService, and National Park Servicee supplied information and otherwise aided inmany ways. A number of graduate students and faculty members were involved in field work,sincerely appreciate the efforts of all those who contributed their time and expertise.LITERATURE CITEDBARBOUR. R. W.. and W. H.DAVIS. 1969. Bats ofAmerica. Univ. DALQUEST. W. W. 1947. Notes on the natural historv of the batPress ofKentucky. Lexington. 286 p. Corynorhinus rafinesquii inCalifornia. J. Mammal. 28:17-30.89Journal of the Arkansas Academy of Science, Vol. 32 [1978], Art. 31Published by Arkansas Academy of Science, 19781General NotesGRAHAM,R.E. 1966. Observations on the roosting habits of thebig-eared bat. Plecotus townsendii. in California limestonecaves. Cave Notes 8:17-22.HANDLEY. C. O.. JR. 1959. A revision of American bats of thegenera Euderma and Plecoius. Proc. U. S. Nat. Mus. 110:95-246.HARVEY. M. J. 1975. Endangered Chiroptera of the southeasternUnited States. Proc. 29th Annu. Conf. S. E. Assoc. Game andFish Comm. 29:429-433.HARVEY. M. J. 1976. Status of endangered bats in the easternUnited States. Proc. 1976 Nat. Speleol. Soc. Annu. Convention1976:21-24.HARVEY. M. J. 1978. Ozark big-eared bat. InH. O.Hillestad. ed.Endangered and threatened vertebrates of the southeast. TallTimbers Res. Sta. Bull. Inpress.HUMPHREY. S. R. 1969. Disturbances and bats. Oklahoma Under-ground 2:42-44.HUMPHREY. S. R.. and T. H.KUNZ. 1976. Ecology of a Pleisto-cene relict, the western big-eared bat (Plecoius townsendii), inthe southern Great Plains. J. Mammal. 57:470-494.McDANIEL. V.R.. and J. E. GARDNER. 1977. Cave fauna of Ar- Ikansas: vertebrate taxa. Arkansas Acad. Sci.Proc. 31:68-71.PEARSON. O.P.. M.R. KOFORD. and A.K.PEARSON. 1952. Re- Iproduction of the lump-nosed bat (Corynorhinus rafinesquii) in \California J. Mammal. 33:273-320.SEALANDER. J. A.. JR. 1951. Lump-nosed bat in Arkansas. ].Mammal. 32:465.SEALANDER, J. A.. JR.. and H.YOUNG. 1955. Preliminary obser-vations on the cave bats ofArkansas. Arkansas Acad. Sci. Proc7:21-31.SEALANDER. J. A.. JR. 1956. A provisional check-list and key tothe mammals of Arkansas (with annotations). Amer. Midi.Natur. 56:257-296.TWENTE. J. W. 1955. Aspects of a population study of cavern-dwellingbats. J. Mammal. 36:379-390.U. S. DEPARTMENT OF THE INTERIOR. FISH ANDWILDLIFESERVICE. 1973. Threatened wildlife of the United States. U. S.Dep. Interior. Resource Pub. 114. 280 p.-MICHAELJ. HARVEY. MICHAELL. KENNEDY,and V.RICK McDANIEL.Ecological Research Center. Department of Biologv. MemphisStale University. Memphis. Tennessee 3HI52. and Division ofBiologicalScience. Arkansas Slate University. State Universiiv. Arkansas 72467.THE DESIGN AND CONSTRUCTION OF AN INEXPENSIVE ANECHOIC CHAMBERWhen any degree of precision is needed in obtaining data on the radiation properties ofan acoustical device such as a loudspeaker or musi-cal instrument, measurements are usually taken under free space conditions without the presence of complicating stationary save patterns.Indoor free space measurements require an anechoic room, a room withcompletely sound absorbing walls. However, a specially designed cham-ber can be used as a good approximation ofan anechoic room. •Aportable chamber, as detailed inFigures 1 and 2. can be utilized as an anechoic chamber. Innever having any opposite wall face parallel toanother, stationary wave patterns willbe prevented from establishing themselves. This, combined with the greatly increased surface area due to Vapproximately thirty-fivehundred polyurethane wedges, willgive the central area of the chamber an anechoic effect. Transmitted noise from out-side the chamber is prevented by insulating the chamber withrock wool fiberglass and acoustical ceiling tile.The walls of the chamber consist of four layers. The outer external layer consisting of three-quarter inch plywood, and. although its primarypurpose is that of the skeleton of the chamber, italso serves as the first barrier against external noise. The second layer consist of two inches ofrock wool fiberglass insulation, acting as an acoustical absorber of any noise which is able to penetrate the external layer. The third layer, three-quarter inch acoustical ceiling tile, provides three functions: acting as a final barrier to incident noise from the outside, providing a base fromwhich the polyurethane foam can be attached, and absorbing sound generated from the inside of the chamber. The inner layer is a polyurethanefoam forming a mosaic of alternating vertical and horizontal wedges projected normally from each surface. Each foam wedge is four squareinches at its base and projects four inches toward the central area of the chamber.The chamber is constructed in two equal parts, allowingfor greater mobility,and joined witha latched tongue and groove joint.Steel mesh -.serves to support equipment placed in the chamber. Quarter-inch holes packed with insulation are placed on either end of the chamber givingaccess formicrophone leads orany other test equipment leads.While this chamber will not replace a complete fullsize anechoic room, it willallow for acceptable measurements of acoustical radiation.However, certain limitations are inherent in the dimensions of the chamber. Frequencies lower than 1000 Hz are ofsufficient wavelength to causeconcern. Any application of the chamber should be restricted to making measurements of radiation above the 1000 Hz limit.Measurements ofhigh frequency resonance response characteristics of string instruments, frequency response of loudspeakers, or frequency characteristics ofmicrophones are but a few of the applications of the chamber.This chamber was constructed using funds from a grant made possible by the Bendix Corporation through the Society ofPhysics Students.?Figure l(a). End view of chamber showing cut out view of the insideand the locations of: (It- latches. (2)-polyurethane foam wedges.(3)-3/> inch acoustical ceiling tile. (4)-2 inches rock woolinsulation.(5)- V4 inch plywood. Figurelib).Side view of chamber showing placement ofa lest objectsupported by wire mesh.90 Arkansas Academy of Science Proceedings, Vol.XXXII,1978J90Journal of the Arkansas Academy of Science, Vol. 32 [1978], Art. 31https://scholarworks.uark.edu/jaas/vol32/iss1/31

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Status of the Endangered Ozark Big-eared Bat (Plecotus townsendii ingens) in Arkansas

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