Thelisteningroom
Mostpeoplehaverelativelylittlecontrolovertheirlisteningroomin
termsofsizeorshape,butastheenvironmentinwhichtheloudspeaker
isusedplayssucha bigpartinthequalityofsoundwehear,some
commentsonroomcharacteristicsmaybehelpfulbeforeweproceed
insection3.
Therearetwoaspectsoflisteningroomswhichwillmostwidely
influencesoundreproduction: Thebasicdimensionsoftheroomand
largeitemsoffurniturecontrollingthelowerfrequencies;anditemsof
softfurnishingtogetherwithwallandothercoveringsaffectingthe
middleandupperfrequencies.
Allroomshaveresonances,andsoindeeddoestheconcerthall,but
inthecaseofthelatterthesearesolowinfrequency,andbydesign,
sowellspacedthattheyaddambienceratherthancolouration:The
worstexampleina listeningroomorstudiowouldbetheunlikely
eventofalldimensionsbeingthesameandtheroomforminga cube.
Thebestcasebeinga relativelylargeroomwherealldimensionsare
different.Fortunatelytheworstexampleisrarely,ifever,encountered
butwherea choiceispossibleasbetweena squareorrectangular
roomthelatteristobepreferredastheroomresonances— knownas
eigentones— occuratspacedfrequenciesandarethereforeoflower
amplitude.
Themostpronouncedeigentonesoccuratlowfrequenciesbelow
approximately200Hz.Inadditiontotheseeigentonesthereisanother
importantinfluencetheroomhasovertheloweroctavesofreproduced
sound.Duetotherelativelysmalldimensionsoftheloudspeakercom-
paredwithwavelengthsofsoundintheloweroctaves,theradiation
patternordistributionofsoundatthesefrequenciesiseffectively
spherical.Whenoperatinga loudspeakerina room,thissphereof
soundiscontained,toa greaterorlesserdegree,dependingonposition
withina seriesofplainsurfacesformedbythewalls,floorandceiling.
Thisproducesa factorknownas'roomgain'anddoesinfactmake
thelowerfrequenciesconsiderablylouderthanif,forinstance,the
loudspeakerwereoperatedintheopenair.
Asa resultofresearchcarriedoutintothe"roomgain"andhowthis
affectsloudspeakerperformance,thestandoftheDM70hasbeen
specificallydesignedtogiveoptimumresultsovera rangeoflistening
conditions.
Beforeleavingthewayinwhichtheroomaffectsthelowfrequency
partofthesoundspectrum,a wordshouldbesaidontheconstruction
Thelisteningroom
