Page 32 - Spring 2019
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Figure 2. Measured impulse responses (ms) from the Rachel Carson Music and campus Center Recital Hall, Concord MA. Both ms were
measured with an omnidirectional (dodecahedral) loudspeaker, band-puss filtered in a 1-kHz octave band, and color coded by temporal
region. Lefi: IR, measured with an omnidirectional microphone, shows relative timing and level ofrefiections arriving from all directions.
Right: IR, measured with a multichannel directional microphone, shows relative level and spatial distribution ofrefiections. Photo by Kelsey
Huchgmf
UsingAuditary Stream Segregation to Decade instruments and from reflections in the room. Although the
a Musical Peijfurmanee brain may perceive the auditory streams separately, the source
One innovative approach is based on the principles of au- and room responses are dependent on each other acoustically.
ditory stream segregation, building on Bregman’s (1990) Developing a better understanding of this relationship, both
model of auditory scene analysis. According to this model, spatially and temporally, is critical to integrating the range of
the brain decomposes complex auditory scenes into separate acoustical percepts more holistically in the future.
streams to distinguish sound sources from each othe: and sem.ngAmusfiml Gmdsfmu New Cmmertflau
from the background noise. The cocktail party effect is a . .

_ _ _ Without one set of perceptual factors to guarantee acoustical
common example of auditory stream segregation, which de- .

_b h 1 _ 1 f _ excellence, who determines how a new concert hall should
SC“  o_w a Per_s°n can Se efutily (Luis on_ 3 single Con‘ sound? In recent interviews between the author of this arti-
vers_a l°n_m a nm_sy room ye S 1 _ 5“ common? Y pmcefs cle and acousticians around the world, three typical answers
auditory information from the noise (eg., the listener will d_ ‘h h ‘h . . b. .

tice if someone across the room sa s their name) See the merge I e 0“ (mm, 6 acousuclm) or a Com mam)“
11? _ _ _ _ _ Y _ _ ‘_ _ of both. Scott Pfeifl’er, Robert Wolf}, and Alban Bassuet dis-
discussion of similar issues in classrooms in Leibolds article . .

_ _ _ _ cussed the early design process for new concert halls in the
In ‘his Issue ofAamsms Todd}/' United States which often includes visiting existing spaces so
In a concert hall, the listener’s brain is presented with a com- that the orchestra musicians, conductor, acoustician, and ar-
plex musical scene that needs to be organized in some way chitect can listen to concerts together and discuss what they
to extract meaning; otherwise, it would be perceived as noise. hear. Pfeifl’er (personal communication, 2018) expressed the
Supported by research studies at the Institute for Research and value of creating a “shared language with clients to allow
Coordination in Acoustics and Music in Paris, Kahle (2013) them to steer the acoustic aesthetic.” Wolff (personal com-
and others have suggested that the brain decomposes the au- munication, 2018) mentioned that orchestra musicians often
ditory scene in a concert hall into distinct streams: the source have strong acoustical preferences developed from playing
and the room. If listeners can perceive the source separately with each other for many years and having frequent oppor-
from the room, then they can perceive clarity of the orches- tunities to listen to each other from an audience perspective.
tra while simultaneously experiencing reverberance from the Bassuet (personal communication, 2018) asserted that it is
room. Griesinger (1997) has suggested that this stream segre- more the acoustician’s responsibility to “transpose into the
gation is contingent on the listeners ability to localize the di- musicians head when designing the hall” and set the percep-
rect sound from individual instruments separately from other tual goals accordingly.

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