a unit of I Logy Services And Solutions

SOUNDPROOFING AND SOUND ABSORPTION

APPLICATIONS

Our products and solutions cover a wide range of applications for acoustic insulation and acoustic correction in buildings as well as Industry.

INDUSTRIAL SECTOR

Acoustic insulation of vibrations of steel or aluminium metal plates, for containing engines, compressors, air conditioning units...

Soundproofing of gutter pipes...

Damping vibrations in cars, buses, tractors and trains.

Acoustic insulation of doors, shutter box, etc.

Sound absorption for industrial cowling, compressors, generators, electric motors, heating systems, automotive/rail/aircraft soundproofing, treating machine housings and enclosure walls etc.

CONSTRUCTION SECTOR, NEW WORKS AND REFURBISHMENT

Acoustic insulation in vertical walls made of gypsum plasterboard or fibre plasterboards, as well as ceramic brick, concrete blocks etc.

Acoustic insulation of ceilings.

Acoustic insulation against impact noise and vibrations in parquet, wooden, and floating floors as well as under mortar screed floors.

Acoustic insulation of airborne noise in metal and timbered roofs. Acoustic insulation of rain-fall noise on metal and timbered roofs.

Acoustic insulation of waste-water pipes, drainpipes and vents.

Reduction of reverberation time in a machinery room, home cinema room, open space, restaurant, library, sound-absorbing speakers etc.

Our diverse clientele includes commercial enterprises, educational institutions, government agencies, architects, interior designers, and residential clients seeking superior acoustic solutions.

At Assam Acoustics Co., we transform spaces through the science of sound, ensuring that every environment is acoustically optimized for the comfort and enjoyment of its occupants. Partner with us for a harmonious acoustic experience like never before.

Noise Challenges we face

Noise and noise pollution surround us on a daily basis (in homes, schools, hospitals, restaurants, at work, etc.). Added to this is the strong urbanization and the multiplication of means transportation in cities.

For this, we seek to improve the quality of life in buildings through better acoustic comfort. Overall, poor sound insulation in buildings impacts from 10% to 20% the value of the property exposed to neighborhood noise.

UNDERSTANDING AND MEASURING Sound & Noise

SOUND

Sound is a vibration that travels through the air and causes a hearing sensation. 2 main parameters characterize it: frequency & sound level (or scale).

FREQUENCY is measured in hertz (Hz); the young and healthy human ear can perceive frequencies between 20 Hz & 20,000 Hz, with a different sensitivity depending on the frequencies.

The scale of perception of the human ear being very vast, we use in practice a logarithmic scale to characterize SOUND AMPLITUDE. The SOUND LEVEL expressed in decibel (dB) characterizes the intensity of a sound and in particular its frequency.

NOISE

NOISE is the set of sounds produced by more or less irregular vibrations, which are often perceived as a nuisance. The smallest variation likely to be perceived by the human ear is of the order of 2 to 3 dB (A)

Sound constitutes a primary source of disturbance, permeating buildings via interior spaces, materials, openings, and structural elements. The consideration of acoustic comfort emerges as a crucial factor in the building design process. Buildings contend with a multitude of noises originating both externally and internally. To enhance acoustics, it becomes imperative to adhere to the following key principles.

SOUNDPROOFING:

Sound or acoustic insulation is the chief method for controlling sound propagation in buildings. In particular, sound function is to reduce noise transmission between two premises or, in general, between one enclosed area and another.

TYPES OF NOISE TRANSMISSION IN STRUCTURES: The noise between two enclosed areas in a building is transmitted by three different routes.

1. Transmission through Surface Vibrations:

In this scenario, incident waves induce vibrations in the construction element, subsequently transferring their deformation to the surrounding air. This phenomenon, often termed the "drum effect" or "diaphragm effect," results in the transmission of noise known as airborne noise.

2. Flanking Transmission:

Beyond causing the dividing wall to vibrate, sound pressure influences all adjacent surfaces, transforming them into additional sources of noise in neighbouring areas. This gives rise to the crucial understanding that acoustic insulation calculations, considering only the dividing element, will consistently underestimate the actual insulation due to this flanking effect.

3. Impact on Structural Elements:

Direct impacts with construction elements, such as footsteps or vibrations from operational machinery like lifts and washing machines, generate rapid vibrations that propagate efficiently throughout the entire structure with minimal energy loss. This category of noise is commonly referred to as impact noise.

SOUND ABSORPTION:

Even in a perfectly acoustically soundproofed environment, reverberation behaviours can persist due to surface characteristics, volume, and the presence of highly reflective materials. The phenomenon of reverberation occurs when numerous sound waves reflect, leading to an elevated noise level and a reduction in the intelligibility of spoken words. Absorbent materials, distinguished by their porous structures, efficiently dissipate sound energy as heat.

FORMS OF NOISE REVERBERATION:

1. Direct Sound: Sound travels in a straight line from the source to the receptor without any reflections or deflections.

2. Indirect Reflected Sound: Sound waves bounce off surfaces such as the floor, walls, and/or ceiling, contributing to the reverberation effect in the environment.

REVERBRATION TIME:

When sound emanates from a singular source into open air, it experiences a 6 dB reduction in intensity with each doubling of distance. However, within enclosed spaces, especially those with limited acoustic absorption, sound can persist for an extended duration due to reflections off the walls.

The parameter employed to quantify and characterize the response of different spaces to this phenomenon is the reverberation time (Tr). It is defined as the duration required for a sound pulse or an abruptly terminated continuous sound to diminish by 60 db. Reverberation time exhibits frequency-dependent variations, being lengthier at lower frequencies compared to medium and high frequencies.

To achieve optimal acoustic comfort in interior spaces, anti-reverberation treatment or acoustic correction becomes imperative. This typically involves the application of sound-absorbing materials, whose shape, porosity, and thickness determine their efficacy in reducing sound reflection across various frequency bands.

The crux of acoustic correction lies in controlling the reverberation time. Depending on the intended use of the space, whether it be a restaurant, conference room, classroom, or theatre, a specific reverberation time is required. Consequently, the acoustical treatment is tailored accordingly.

The energy balance in this context can be expressed as follows: The absorbent material minimally reflects energy and transforms a portion of the transmitted energy into a different form.

AIRBORNE NOISE INSULATION IN CONSTRUCTION:

The prevalent mode of noise transmission through the air is airborne noise, manifesting in both outdoor and indoor environments. Examples of outdoor airborne noise include traffic from roads, railways, and air travel, as well as pedestrian activities on the streets. Within enclosed spaces, sources of indoor airborne noise are diverse, encompassing conversations, music, radio, television, and more. Effective airborne noise insulation can be achieved through the application of various construction systems.

SINGLE WALLS:

In the context of a single wall, acoustic insulation relies primarily on its surface mass (measured in kg/m2). This leads to the formulation of the mass law, a fundamental theoretical principle governing the calculation of the insulation index, denoted as R.

According to the mass law, the wall vibrates under the impact of sound waves, transmitting noise to adjacent premises. It posits that lighter and more rigid walls exhibit diminished insulation. Additionally, the law stipulates a 6 dB increase in insulation when the mass is doubled at a fixed

frequency, albeit within the frequency range of 500 to 1000 Hz and up to 45 db. It is crucial to note that the mass law remains theoretical, omitting consideration of other influential parameters like resonance frequency and critical frequency (fc).

Resonance frequency denotes the frequency at which a wall naturally vibrates upon sound wave impact, causing a perpendicular surface displacement known as the "drum effect." This frequency is contingent on factors such as mass, environmental conditions, and the wall's structural attachment. Typically, resonance frequency falls within the realm of very low frequencies.

DOUBLE WALLS:

Enhancing acoustic insulation involves the use of double walls, particularly applicable to lightweight structures. The challenge lies in boosting insulation for heavier walls. The solution involves constructing two single walls spaced a specific distance apart, creating a mass-spring-mass system that offers superior insulation compared to an equivalently massed single wall.

PLASTERBOARD WALLS (LIGHTWEIGHT PARTITIONS):

Commonly used in hotels, offices, hospitals, and housing, plasterboard walls offer the advantage of achieving high insulation values with minimal mass compared to traditional masonry walls. Due to their lightweight nature, they exhibit low insulation to low frequencies. Constructed using self-supporting steel structures with horizontal U-channels and vertical C-profiles, these walls can have one or two independent structures based on the required insulation level. The critical frequency (f) is notably high (2700 to 3000 Hz), remaining independent of the number of plates used.

AIRBORNE NOISE INSULATION IN CONSTRUCTION:

SINGLE WALLS:

DOUBLE WALLS:

PLASTERBOARD WALLS (LIGHTWEIGHT PARTITIONS):

IMPACT NOISE INSULATION IN CONSTRUCTION

inside a room, the sources of nuisance can also be caused by an impact transmitting vibration directly and indirectly to the supporting structure (footsteps, ball, furniture, etc...) coming from the upper floor. To reduce the sound energy transmission of impact, the best solution is to intervene at the floor level that is the source of the noise.

EQUIPMENT NOISE IN CONSTRUCTION

Inside a room, sources of noise can also come from continuous or occasional use of equipment: heating (hydraulic network), elevator shafts, air conditioning ducts, air renewal (aeraulic network), waste-water pipes, etc.

IMPACT NOISE INSULATION

Inside a room, noise propagates throughout the volume and the waves are gradually reflected on the walls until decreasing. For the correct acoustic correction of a room, you must control the reverberation time and the coefficient of sound absorption of the materials constituting the partitions (walls and ceilings). Correcting the acoustics of a room means reducing the reverberation time and improving speech intelligibility. The weather of reverberation varies according to the nature of the constructive elements in the room (tiles, glass, flooring...). Treating the acoustics of a noisy room also means applying solutions with a high absorbency (high coefficient absorption).

MAIN PURPOSES OF ACOUSTIC CORRECTION USING SOUND ABSORPTION ARE:

1. Increasing internal acoustic comfort, reducing background noise.

2. Appointing a venue for it to meet specific requirements.

3. Ensuring that, from the project stage, a building meets the fundamental acoustic conditions for its purpose, such as a theatre, cinema or auditorium.