Download - Exploring Acoustics in the Hopkins Center
Exploring Acoustics Exploring Acoustics in the Hopkins Centerin the Hopkins Center
Scott NiehausScott Niehaus
BackgroundBackground
Sound that is emitted propagates in all Sound that is emitted propagates in all directions as a wave and strikes all surfaces in directions as a wave and strikes all surfaces in its pathits path
Sound can be absorbed, reflected, or Sound can be absorbed, reflected, or transmitted by a surfacetransmitted by a surface– Soft surfaces like carpets tend to absorb sound while Soft surfaces like carpets tend to absorb sound while
hard surfaces like walls reflect soundhard surfaces like walls reflect sound– Absorption coefficients range from 0-1, with 0 meaning Absorption coefficients range from 0-1, with 0 meaning
totally reflecting and 1 meaning totally absorbingtotally reflecting and 1 meaning totally absorbing Engineers target reverberation times of .8-1.0 Engineers target reverberation times of .8-1.0
seconds for band or orchestral rehearsal spaces seconds for band or orchestral rehearsal spaces and 1.0-1.3 seconds for choral rehearsal spacesand 1.0-1.3 seconds for choral rehearsal spaces
Upper BuckUpper Buck
Room Characteristics: shaped like an oval, lots of Room Characteristics: shaped like an oval, lots of hard walls and glass, 93.8 hard walls and glass, 93.8 mm33
Average reverberation time: 0.88 secondsAverage reverberation time: 0.88 seconds Sabine’s formula: TSabine’s formula: T60 60 = .161V/S= .161V/S Absorption coefficient of room: .09Absorption coefficient of room: .09 ART with carpets and comforter: 0.72 secondsART with carpets and comforter: 0.72 seconds
Upper Buck (cont.)Upper Buck (cont.)
Adding carpets and my comforter did not Adding carpets and my comforter did not greatly affect the spectrogram of a piano greatly affect the spectrogram of a piano chord, it only changed the reverb timechord, it only changed the reverb time
Lower BuckLower Buck
Room Characteristics: more rectangular, all walls, Room Characteristics: more rectangular, all walls, larger than UBlarger than UB
Average reverberation time: 0.44 secondsAverage reverberation time: 0.44 seconds ART with carpets and comforter: 0.42 secondsART with carpets and comforter: 0.42 seconds Absorption coefficient of room: unable to Absorption coefficient of room: unable to
measuremeasure
Individual Practice Individual Practice RoomRoom Room Characteristics: 15.6 mRoom Characteristics: 15.6 m33, small box, all , small box, all
walls, but not as smooth as upper buckwalls, but not as smooth as upper buck Average reverberation time: 0.25 secondsAverage reverberation time: 0.25 seconds Absorption coefficient of room: .265Absorption coefficient of room: .265 RT with comforter: 0.21 secondsRT with comforter: 0.21 seconds Absorption coefficient of room with Absorption coefficient of room with
comforter: .314comforter: .314
Absorption CoefficientsAbsorption Coefficients
From the data I gathered I was able to figure out From the data I gathered I was able to figure out the absorption coefficients of my comforter and the absorption coefficients of my comforter and the 3 rugs I used.the 3 rugs I used.
Absorption coefficient of my 3.5 mAbsorption coefficient of my 3.5 m22 comforter: comforter: 0.7960.796
Absorption coefficient of 3 rugs totaling 2.7 mAbsorption coefficient of 3 rugs totaling 2.7 m22 : : 0.300.30
Piano AnalysisPiano Analysis
Short C Major chord bursts of the same volume produce significantly different spectrograms in the 3 rooms
ConclusionsConclusions
Room shape, size, and types of Room shape, size, and types of surfaces present all affect surfaces present all affect reverberation times and sound qualityreverberation times and sound quality
When played on a piano, the shorter When played on a piano, the shorter RTs corresponded harsher timbresRTs corresponded harsher timbres
Individual rehearsal rooms do not need Individual rehearsal rooms do not need a long RT as there is nothing to blend a long RT as there is nothing to blend with when playing alonewith when playing alone
Higher sound quality of Upper Buck vs. Higher sound quality of Upper Buck vs. Lower Buck corresponds with Lower Buck corresponds with sentiments of my a cappella groupsentiments of my a cappella group
The EndThe End