Acoustic seals in architecture

Acoustics play a very important role in building design and construction. Two important areas in particular are laboratories and semiconductor manufacturing facilities. Many of these laboratories and facilities house sensitive and expensive equipment, such as high-power electron microscopes. Electron microscopes are used in the semiconductor industry for circuit editing and analysis. In the field of life sciences, these high-power microscopes are used in research, disease diagnosis, pathology and drug/vaccine development.

Interference from acoustics can cause abnormalities in the high-resolution TEM image, scanning distortions and loss of energy resolution[1]. Today’s electron microscopes perform extended duration imaging for 3D reconstructions, producing fantastic images and data that was previously impossible on older systems. But, creating these images takes many hours or even days. Unwanted interference could be costly in both time and resources. Therefore, sensitive equipment requires careful architectural design of the surrounding area to prevent interference[2].

Sound & Acoustics

Sound is described as vibrations in the air that move in waves. Acoustics in architecture mean improving sound in environments.

Environmental factors

Environmental factors can greatly influence sensitive equipment. For example, vibrations, ambient soundwaves, barometric pressure changes, pipe temperature changes, grounding issues, and electromagnetic fields all contribute to the performance of sensitive equipment.[3]

The STC rating

Sound Transmission Class (STC) is the measurement of the ability of a wall or floor assembly to isolate airborne sound and prevent it from passing from one Class (STC) side to the other.

A higher STC-rated wall generally blocks more noise from transmitting through a partition.[4]

Calculating the STC

To calculate the STC, it is important to understand the main components of this measurement:

• Frequency – the measurement of the tone or musical note of the sound
• Decibel – a measurement of sound intensity; volume
• Transmission loss (TL) – the measurement of the decibel difference on either side of the structure

STEP 1. Measure the “transmission loss” on either side of the structure being measured. This measures the volume (dB) difference on each side respectively.

STEP 2. Transmission loss values are tested individually against eighteen of the most common frequencies spanning a range between 125 Hz and 4000Hz. These measurements are used to map out points on a graph that then form a curve. This curve can then be compared against standard STC reference.[4]

Sound leakage

A wall’s STC rating is also dependent on penetrations through the wall. All holes and gaps should be filled and electrical enclosures hermetically sealed for sound isolation to be effective. Inadequately sealed partitions and unsealed pipes offer paths for sound and significant leakage.[5]

Noise reduction solutions

To reduce the noise from entering and exiting a room – and thereby increasing a wall’s STC rating – one must do any or all of the following:

1. Increase the structural mass of the walls, floor and ceiling
2. Effectively seal the openings for electrical cables, water, and gas
3. Effectively seal the gaps surrounding doors and windows[3]

In summary, acoustics are a vitally important factor to consider in the field of architecture. This is enhanced in laboratories and other advanced facilities. As equipment becomes more powerful and sensitivity levels increase, the need to improve acoustics also increases.