SOUND and NOISE MANAGEMENT

Post 270 – by Gautam Shah

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Sound and Noise, are two irritant aspects of a space design. Both are hard to define and tackle. Clients, Designers, and subject experts, are never fully satisfied by the strategy of a solution finding or results.

In everyday life we use both the terms with different but subjective associations, though sound has more positive affiliation then what noise implies. Noise is a sound, of a type, or rather of a context. Noises are of many types, and have unclear bearing compared to sound that has specificity of quality and origin. The past associations of the perceiver are major determinants, whether a sound is considered as noise or not. Noise and sound are also differentiated on scale of aesthetic awareness. Familiarity or clearer perception can translate an aspect of noise into a sensible experience -the sound.

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The term noise is derived from the Latin word nausea = sea sickness, whereas the word sound derives from soun (middle English), son (Anglo-French), sun (Latin) or sonus > sonare > sound.

Noise, even of regular composition if loud, in the short term disturbs people as it makes it difficult to hear wanted sounds, or breaks their concentration. In physics and science of acoustics, noise is an unwanted random rider to a signal, that generates hiss or static.

Noise is excessive, unpleasant, annoying and unwanted sound which results in annoyance, and in the longer term loss of hearing. Hearing impairment (presbycusis) occurs with age, but noise can hasten it. Noise causes changes in the body immune system, stress, hypertension, ischemic heart disease, tinnitus and vaso-constriction. Noise exposure also creates sleep disturbance increases workplace accidents, aggressiveness and antisocial behaviour.

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Sound, though desirable than Noise, can also be annoying, due to its loudness, perceptive clarity of detail, inability to localize its source, reverberations, unauthorized infiltration into protected spaces, and in substantial absence of it.

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In Space Design the Noise and Sound control mechanisms overlap. Noise mitigation strategies often impact, in suppressing the desirable sounds, removing the background noises, and necessary reverberations that are often required to remove feeling of loneliness and perception of space size, form and other sensorial definitions.

The areas where noise and sound control management become important design issue are: Road, railway and aircraft corridors, cabins of transport operators, industrial plants with impact operations such as forging, transport terminals, public gathering places, underground or covered parking lots, hospitals, sanctimonious locations and buildings. Some spaces like conference halls, auditorium, meeting rooms, concert halls, entertainment and social venues, dining areas, audio recording rooms also need similar attention.

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Noise and sound management techniques include: Insulation prevents transmission of noise or sound across spaces and barriers, by providing appropriate mass and surfaces. Absorption is a quality of mass to convert the sound energy into (micro level) heat within the material. Vibration damping is required to remove vibratory energy getting transmitted in thin body (sheets, tout wires) materials and thereby generate sounds. Examples are air craft and automobile bodies and very thin shell structures or roofs. It can be achieved by isolating vibratory body by including breaks or absorbent elements. Vibration causing sound waves in air, hydro-acoustic waves in water, and stresses in solid matter.

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Complete sound absorption has very important roles in specialty spaces, where a sound, only from a designated source is valued. It means the perceiver, person or device, gets sound without any spatial modifications (reverberations). This is required in a recording studio, sound calibration labs, and non detectable stealth vehicles like air-crafts or submarines.

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The traditional sound and noise handling techniques are based on materials sciences, shape or form configurations, and element siting. These traditional methods required extensive interventions in space, such as partitions, ceilings, floor treatments. These elements use absorbent or insulation materials and techniques that are highly vulnerable to fire and have high ecological concerns. The sound and noise control elements reduced the daylight into deeper spaces and reduced the outdoor viewing. For a unified space configuration, reduction of barricading and intervening elements is very important, which can occur by adopting sound masking technologies.

Sound masking is opposite of soundproofing, as it is an active addition of noise to a space, to counter certain sounds. It is like in an Interior Space where to reduce the glare from an opening, one can either place a curtain on the opening, or put on additional illumination in the room. Sound insulation works like the former and sound masking like the later method.

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Sound masking is addition of natural or artificial sound into a space to suppress the effects of unwanted sound. It is done with specially designed speakers installation to add ‘low level’ sounds over the existing sounds in the space. It reduces the chances of imperceptible sounds coming to a personal field, and affect the concentration or add to distraction. Additional sounds reduce or eliminate the pervading feeling of pre-existing sounds to make living areas more audio-comfortable.

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SOUND -as we listen

Postby Gautam Shah

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SOUND is sensorial perception received mainly through the Ears, but often through the Skin of the body. The ears are on either side of the body, and so are able to distinguish the sound from left or right fields. The ears are able to distinguish pitch and intensity of the sound and thereby roughly determine the source, its distance and the nature of medium through which the sound has arrived.

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In technical sense Sound is caused by the Mechanical disturbance in a solid, liquid or gaseous materials. These materials have varying degree of Elasticity to act as the sound transmitting medium. The vibrating objects could be the vocal cords of a person, string and sound board of a guitar or violin, tines of a tuning fork, or the diaphragm of a radio speaker. Music is formed of one fundamental frequency, and several other integral multiples of this basic frequency, called harmonics. A pure Tone of sound, composed of only one frequency is one that is produced by a striking fork.

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Sound producing or vocal organs are many such as: lungs, windpipe, throat, larynx, nose and mouth “The vocal organs –are primarily for breathing and eating. The lungs act as bellows. The vocal cords or folds of the larynx vibrate as double reeds. The cavities of the throat, nasal sinuses, and mouth act as resonating chambers, with the size of the mouth cavity varied by jaw movement.”

Human voice is more versatile than any other musical instrument. Sarangi (Indian musical instrument which has guts -instead of wires, and played with a bow, its markers are created by pushing the gut upward over the fingers) emulates sounds that are closer to human voice.

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Vibratory energy that is perceived by the human ear or the audible sound is termed as audio or sonic. Audible range of frequencies for a normal young person is 20 Hz to 20000 Hz (1 Hertz = 1 vibration/second). Very low frequency (infra sound lower then 20Hz) or very high frequency (ultra sound beyond 20000Hz) are not perceived by the human ear. Actual audio capacity of an individual person varies a lot. Intelligible human speech occurs in the range of 600 Hz and 4000 Hz.

Caissons_grave_DSC_5563ECThe ears of children respond to very high frequency sounds which by adulthood narrows to about 15-15000 Hz. The loss of hearing in adolescence, approximately 80 Hz every six months, becomes noticeable years later. An aged person may not hear high frequency sounds such as ticking of a watch or certain high frequency consonant sounds.

EdisonLaboratoryMusicRoom1905smHuman ear or mind has enormous capacity to discriminate and to extract the required information from the background noise and signals. The Noise -the unwanted range of Sound is below 200 Hz. However it cannot separate out sounds that are close either in frequency or in time. A human ear has greatest sensitivity between 100-4000 Hz.

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General room noise masks the traffic noise, making it less noticeable, or the traffic noise may mask the conversation taking place in the room. It often happens that in an attempt to reduce the external sound penetration through efficient insulation, enhances the internally occurring noises. Inversely by eliminating all the internal noises one may enhance the effect of sounds arriving from outside.

A modern good quality PA system should be capable of 100 Hz to 6000 Hz and preferably 10000 Hz. For music the PA system should be 80 Hz to 10000 Hz and up to 15000 Hz for high quality theatre type of installation. Some sound equipments include loudness control by attempting a degree of compensation by boosting bass and possibly treble at low listening levels.

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This means that if a sound is reproduced at a higher level than at which it was recorded, then the low frequencies will become relatively louder (speech will sound boomy). If it is reproduced at a lower level then it will sound `thin’ and lack bass (orchestra reproduced at a small room level).

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PERCEPTION of SOUND and SPACES

Post -by Gautam Shah

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Most experienced speakers, stage actors and musicians (vocal and instrument players) have an innate or learned capacity to improvise their output immediately on encountering a new space. They readjust -their output according to the audio response from the nature of space.

The Nature of Space is determined by several objective and Subjective factors.

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The objective factors are the size, scale, shape and form (hard vs soft surfaces) of the architectural space. Other objective factors include degree of echoes or reverberation in the space, quality of public address system, location and direction of the speaker or musician, etc. The occupancy or crowding in the space, and the nature of garments, furniture and furnishings also affects the perception of sound. The background noise seeping to the speaker or performer’s area and the audience, or to the listener (in small gatherings) could be very different. This means that a performer may not perceive the audience or listener’s environment. Only way to sense this is through the recognition of behavioural responses. Experienced speaker or performer raises the voice and change the tonal quality, and if there is a longer reverberation, the pauses are widened and delivery stretched in time.

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Speaker or performer sense the space and focus the address to that part of the audience, where Sound delivery is perceived to be inadequate. The performer use enlarged body language and dress movements to supplement the Sound.

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The Art of Noises (Italian: L’arte dei Rumori) is a Futurist manifesto written by Luigi Russolo in a 1913. Russolo argues that the human ear has become accustomed to the speed, energy, and noise of the urban industrial sound-scape. He proposes a number of conclusions about how electronics and other technology will allow futurist musicians to ‘substitute …. infinite variety of timbres in noises, reproduced with appropriate mechanisms.

Russolo states that noise first came into existence as a result of 19 C machines, before this, the world was a quiet, if not a silent place. The prominent noises were of storms, waterfalls, and tectonic activity. The noises were not loud, prolonged, or varied. Russolo claims that music has reached a point that no longer has the power to excite or inspire. It still sounds old and familiar, leaving the audience. Wide arrays of noises are taken for granted, yet (potentially) musical in nature.

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The variety of noises is infinite. If today, when we have perhaps a thousand different machines, we can distinguish a thousand different noises, tomorrow, as new machines multiply, we will be able to distinguish ten, twenty, or thirty thousand different noises. He wants musicians to pay attention to noises and their complexity.

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