HEARING and interior spaces

Post 383 – by Gautam Shah

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Hearing reveals multiple facets of architectural spaces through a very comprehensive experience. The experience is not focussed like vision, but substantially includes many convergent audio ‘effects’. This effects have clueless or orientation-less feel. Visual knowledge is more metrical compared to hearing which is abstract.

A normal person relies more on directed visual clues than diverse audio feeds. This is because visual information can be perceived and processed faster, whereas the audio cognition needs sustained understanding of the space making elements.

abandon_alley_architecture_black_city_corridor_dark_derelict-1358067.jpg!dThe audio information in a space is made of: 1. Direct sounds, 2. Reverberated sounds from different distances, surfaces and directions and, 3. background noises that enter the space. The hearing becomes more complex, when sounds get mixed to depress or enhance certain frequencies.

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The space making elements, such as materials and their surfaces, the shape and the size, format the space hearing experience. This was realized from primitive times. Architectural spaces were exploited (rather than designed a fresh) for the hearing related inherent space facilities. This was possible with sporadic success. Acoustics for new spaces were always an unpredictable exercise.

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Continuous use of known spaces, sizes, and shapes give a predictable audio experience. Religious buildings, amphi theatres, meeting halls, were such oft repeated works. The visual and tactile knowledge of the space helped mould it for hearing. Opera and concert spaces were fine tuned for such combined sensorial experiences.

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Opera and concert halls over a period have fashioned the architecture of sound transmission exploiting the shape and size, beyond the surface qualities. Parabolic ceilings, inclined walls, convergent or conical forms were involved in interior articulation of the space. Even then within a space there were great many locally variegated experiences. A church, concert hall or assembly hall always had few pockets of poor hearing.

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In all large spaces the spatial experience was moulded by direct and reverberated sound synchronized with relevant visual clues. Greek and Roman theatres were designed to bring the audiences closer to the stage so that audio-visual experience would become one. These were reinforced with loud and emphatic dialogue delivery, use of extra ordinarily flocked dresses and highly articulated postures and gestures. These traditions also continued in dramas, operas and other musicals. The techniques were, however, not freely applicable in sombre religious ceremonies.

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For Peter Zumthor the Interiors are like large instruments, collecting sound, amplifying it, transmitting it elsewhere. That has to do with the shape peculiar to each room and with the surface of materials they contain, and the way those materials have been applied.’ Corridors or passages are considered eerie places, not just due to poorly lit and unexciting architecture but the sound quality.

glacier-and-hiker-725x482Hearing nothing is like hearing through sea shell that re-transmits all sounds baffled by a wall and its labyrinth form. The Pantheon or cave recall this ‘absence or absorption’ of sounds. Architectural acoustics was once about managing the outside noises and inside sounds. The former was solved by isolation from surroundings, and the later by spatial modulation.Trees barriers

Modern technology of hearing, deals with the presence and absence of sounds, in the work places. One may not desire to eavesdrop a colleague talking to another co-worker or a wife at home. In highly insulated work space the complete absorption of such noise is as much a problem as the inability to suppress such sounds. These are now managed by adding additional sounds (white noise) through special type of speakers. The speakers output sounds in set frequency range to cancel (sound making – white noise) out the irritant sound presences.

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ACOUSTICS in SMALL SPACES

Post -by Gautam Shah

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Singing in a bathroom sounds lively, but only to the person in the bathroom, because the reverberated sound seems to be richer, and fuller. A bathroom also offers a very private space for uninhibited behaviour.

Small rooms like a bathroom have small sizes, and smaller volumes. Such spaces include an inner sanctorum of temples, confession booths, personal prayer rooms, private offices kitchens, study rooms, store rooms and telephone kiosks. These rooms are used for personal meditation, prayers, recitation, singing, self-talk or person to person (one to one) voice communication (directly or through telephony).

There are two major qualitative characteristics of these spaces: Smaller size resulting in Smaller volume, and the Nature of furnishings. A bathroom like spaces are bereft of any soft surfaces, whereas study room like spaces are over furnished. But all small spaces allow multiple reflections from architectural boundaries and enrich the sound of one’s voice.

A study room made ‘cozy’ with heavy furnishings, draperies, thick walls become a sound absorbent environment. Here the richness of the bounced or reflected sound is lost. The highly isolated space cuts-off the low frequency ‘interference’ of outside noises like traffic, wind, rustles of the leaves, etc. The absence of background noises does not mask the internal low frequency noises of the room. As a result sounds our own body movement, rustling sounds of clothes or book pages, fan or air conditioner’s hiss etc. are over emphasized and become disturbing.

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The acoustical properties of small rooms differ considerably from that of large rooms, such as the auditoriums, concert halls, cathedrals, lecture halls, etc.

● In a large room, first-arrival times of the early reflected sound are typically on the order of # 50-80 ms after the direct sound.

● For small rooms, the first-arrival times of the early reflected sound are # few ms after the direct sound.

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For heavily furnished ‘Home rooms’ the sound absorption properties of the room often are significantly higher than in large rooms. Small rooms often provide the ‘acoustic intimacy’ but do not have ‘acoustic grandeur’ of very large spaces. Large rooms have distinctive reflections which help us comprehend our location, the direction and distance of objects etc. In large rooms there are likely to be few surfaces that are horizontally askew, vertically inclined and surface quality wise irregular so some blurring of the reflections is inevitable.

In a space original sound travels more or less straight to the listener whereas the reflected sound must travel towards a boundary and then get bounced back to the listener. Such delayed reflections heard along with the original source sound are the cause of echoes.

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Reflections often obscure the true source of a sound and reduce intelligibility. This effect is more pronounced in small rooms than larger ones because the walls are closer together and so the reflections are stronger. However, the strength of the reflections also depends on the density of the walls, with rigid walls reflecting more and to lower the frequencies. Indeed, the worst environment for a home studio is a basement because cement walls are more rigid than partition or thin body walls. Thick walls around small space rooms improve the acoustic isolation but thin partitions allow lower frequencies to pass through to get absorbed within the body or expended in vibrating the thin body mass.

669px-Jan_Vermeer_van_Delft_014In the natural world without walls or ceilings, the First Significant Reflection will always come from the ground. We subconsciously use the FSR to determine distance from an object. For example a person speaking to a listener from 2′ distance, the initial sound will arrive about 2ms while the FSR will be about 11ms. Thus effective FSR is 9ms (11-2=9ms) to the listener. If the speaker is 10′ away, the FSR will be about 5ms from the listener’s perspective.

Size and Shape of a room affects the quality of sound in a room. ‘In a room with parallel walls (almost all rooms), the sound gets a caught bouncing back and forth between the walls. Some sound waves are cancelled by their own reflections while others are reinforced’. However, in a room with slightly askew walls can drastically reduce the redundant reflections between walls. Ancient Greeks found that rooms with the ratios of 2.62: 1.62:1 sounded universally good.

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Regent Park audience Wikipedia Image by TomIAnderson

One of the famous sermons from Jesus was made at the bottom of a hill while the audience was on higher ground Here Jesus was addressing a very large audience from a Low position. Since this was in the morning, the audience was in the optimal position to hear and see him speak, The hill helped capture the speech and block out extraneous noise.  ( This is as per the Literary description, Paintings illustrate superior-higher position for the Christ).

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