ACOUSTICS in SMALL SPACES

 

Singing in a bathroom sound 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.

HaydnPlaying

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.

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In 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 affect the sound of 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.

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2 thoughts on “ACOUSTICS in SMALL SPACES

  1. Pingback: SPACES >> Select LIST and LINKS to BLOGS | Interior Design Assist

  2. Pingback: BLOGS LINKS about PERCEPTION | Interior Design Assist

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