Aural Architecture

    A general knowledge of physical acoustic properties is definitely an asset to anyone involved in sound related work. An interesting place to start could be acoustic concert halls and the science behind the aural - architectural relationship.

    Wallace Sabine designed Boston Symphony Hall in 1900 which was the first Music Hall built with acoustic engineering principles applied to it's architecture. His calculations on ideal reverberation time laid the foundations for architectural acoustics. Today, additional factors outside the realm of sound dispersion/physics are considered such as the subjective preferences of listeners and performers.
    Things like Initial Time Delay Gap and Clarity Index are taken into account and used to measure direct and reflected sound. A direct sound is a pure tone without any audial pollution. An orchestra depends heavily on direct sound for added clarity to the listeners however reflected sound can add richness to musical tones. Reflected sound can also create distracting "muddy" tones depending on varying physical and objective parameters. Every orchestral arrangement will have an ideal clarity index depending on the instruments used during the performance, vocal ranges, musical repertoire, etc. Different materials are used to absorb/reflect different sounds. Sabine determined that one surface will function differently towards various frequencies: a high note played on a violin, for instance, will be absorbed more than a low note played by a double bass. Porous absorbers in the concert hall will absorb high frequency sounds more so than resonant absorbers, which respond to low frequency sounds. Early sound reflection is important for performers to be able to hear what they are playing while there is an equally as important need for extended reverberation in order for the room to facilitate the musicians efforts to fill the space.
    All venues will vary in terms of dryness and reverberation. A listener in a shoebox shaped hall will experience immediate sound reflection due to sound bouncing parallel off the narrow walls. This creates strong acoustic intimacy, warmth and listener envelopment. A fan shaped venue will have longer reverberation time due to the distance created between the walls and ceiling. This can add depth to a performance but it may also create echoes which could become somewhat of an annoyance to performers on stage. Singers and solo musicians must perform more efficiently in dry rooms as their sound is unequivocally accurate. The most practical auditoriums are those which can be modified to suit the needs of the musical arrangement, accommodating for speech as well as vocal and instrumental performances. Interchangeable sound baffles, removable panels and seal-able chambers can be altered accordingly. Some larger fan-shaped venues will hang panels from the ceiling (called clouds) to address potential reverberation issues. (These become visually stimulating as well.) Materials as uncontrollable as the audience's clothing will ultimately affect the sound absorption of a music hall, so there are indeed many different elements to consider when dealing with architectural acoustics. I've hardly scratched the surface.

    Sabine has argued that before such critical analysis of acoustics and architecture, there was an inverse relationship between the construction of musical pieces and buildings. Instead of building to accommodate different musical styles, music was probably written to suit the popular architectural forms of the era. The accessible materials and architectural styles of a specific area may have influenced the musical development in those areas, unbeknownst to anyone at the time. "The cavernous, highly resonant stone buildings of the Romanesque period allowed vocal tones to linger, supporting the exploration of rich vocal harmonies, characteristic of choral music of that era... The development of ornate contrapuntal Baroque music with its complex interplay of melodies may be due to the horizontal clarity of the classical outdoor amphitheater, which evolved into the horseshoe shaped concert building" (Forsyth, Buildings for music, 1985.)

    Next thing to take note of is how amplifiers and loud speakers are used in arena rock concerts nowadays... How would a band adjust from playing a small venue to an arena built to house a hockey game? How would a band accustomed to playing large arena venues adjust to playing in one shaped like a saddle...


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