Foundational Knowledge of Noise Reduction

Achieving a properly balanced room with ideal acoustic levels is crucial for the productivity and comfort of workers globally.

To treat sound in a room, it's essential to have a grasp of the fundamental acoustics terminology. Just like anything else, a solid foundation is vital for better acoustic performance.

This guide covers the following topics:

1. Definition of sound, including frequency, decibels, and reverberation time

2. Building acoustics vs. room acoustics

3. Principles for excellent acoustics, including absorption, attenuation, and diffusion.

1. Sound Defined

Sound is comprised of pressure waves traveling through the air, characterized as energy generated by vibrations propagated through the air or other media. The vibrations are transformed into electrical signals by the inner ear, which are then transmitted to the brain for processing and perception as audible sound. These sound waves have two distinct qualities: frequency, which determines the pitch, and decibel, which determines the volume.

— Frequency: How sound waves move
Frequency is calculated as the number of repetitive vibrations per cycle per second and is measured in Hertz. The audible range of sound is between 20 to 20,000 Hz. A higher frequency corresponds to a higher pitch. However, when it comes to space planning, the suggested frequency range is between 100 Hz to 5000 Hz.

High-pitched sounds, such as ringtones and consonants, have a frequency of 2500 to 12000 Hz and a short wavelength.

Mid-range sounds, such as speech, have a frequency of 250 to 2500 Hz and a medium wavelength.

Low-pitched sounds, such as HVAC and vowels, have a frequency of 50 to 250 Hz and a long wavelength.

— Decibel: measuring sound intensity

Decibel is a logarithmic unit that expresses the ratio of sound intensity (loudness) and is used to gauge the level of background noise. The range of sounds humans can hear is from 0 to 140 decibels. The value of decibels has no direct or indirect connection to sound frequency.

For instance, the sound of a clock ticking and the noise of a vacuum cleaner may have the same frequency but different volume levels.

Why is this important? In modern open-plan offices, employees are exposed to excessive noise levels, which can range from 60 to 80 decibels, whereas the recommended background noise level in an office is approximately 45 dB.

Offices that exceed the suggested threshold of noise may impede:

1. Concentration

2. Collaboration

But there are methods to minimize stress by creating several workplace microenvironments that are designed with sound balance in mind, considering the activity and the people who will be using these areas.

— Reverberation time: when the sound fades to silence

Reverberation time refers to the duration for an initial sound source to diminish by 60 dB, expressed in seconds. Achieving exceptional speech intelligibility and clarity involves adjusting and balancing the reverberation time through absorptive materials tailored to specific acoustical challenges in a given space. Factors that always influence the reverberation time include:

1. The size of the room

2. The temperature of the room

3. The materials, objects, and people in the room that absorb sound

The recommended reverberation time varies according to the intended use of the space:

- Office: 0.75s

- Meeting room: 0.60s

- Cafeteria: 1.00s

- Gymnasium: 1.50s

- Auditorium: 1.50 to 2.00s

Why is it important to consider reverberation time? In an office, excessive reverberation can exacerbate existing distracting sounds, as the sound bounces off walls and tables, among other hard surfaces. For example, it can result in difficulties understanding conversations with colleagues or being distracted by people speaking on the other side of large spaces. The solution to dampen reverberation is through the use of sound-absorbing materials.

2. Room acoustics vs Building acoustics

Building acoustics and room acoustics may seem similar, but they require different approaches to resolving issues. Building acoustics concerns the transmission of sound from outside and within a building, such as from outdoor traffic or footsteps from an adjacent floor. This can be addressed by insulation of windows, walls, ceilings, and floors, or by reducing the transmission of sounds from the source. In contrast, room acoustics focuses on sound waves within a room, and the best solution is to use absorption materials to prevent sound waves from reflecting off surfaces and creating echoes.

3. Principles for superior acoustics

Our acoustic solutions are designed to enhance the sonic ambiance within a room, effectively reducing reverberation time. These solutions are based on one or more of the following key acoustic principles.

— Absorption

When sound waves encounter acoustically soft materials, they are absorbed. Sound, being a form of energy, must be transformed into heat through friction to prevent it from continuing to travel. The effectiveness and extent of this absorption are gauged by the absorption coefficient of the material in question. Absorption treatments can be integrated into permanent wall or ceiling features.

— Attenuation

This principle involves the reduction of sound transfer within a room. To minimize the transmission of sound between different spaces, vertical elements are employed to diminish sound energy. These elements can be suspended from the ceiling or stand freely and may manifest as vertical ceiling panels, room dividers, desk screens, or a range of other acoustic tools. The significance of attenuation or sound dampening in improving speech intelligibility and clarity is vital. A positive acoustic environment that absorbs disruptive noises fosters a quieter atmosphere, enhances concentration, and facilitates productive collaboration in a dynamic workspace.

— Diffusion

This principle ensures that sound energy is evenly distributed throughout a space. Wavelengths that are not absorbed by acoustic treatments are dispersed uniformly back into the room, leading to a more balanced auditory experience and preserving the liveliness and vibrancy of sound. Without diffusion, sound would reflect linearly, creating an unpleasant and lingering noise. Achieving diffusion can be accomplished through the use of materials with varying depths of absorption and 3D shapes.

In addition to these principles, our solutions also incorporate advanced audio equipment such as active monitors, powered monitor speakers, and active monitor speakers. These high-quality devices are essential for accurate sound reproduction in professional settings like studios and stages. For live performances, powered stage monitors and powered studio monitors are indispensable, providing clear and direct sound feedback to performers. Whether you're in need of active studio monitor speakers for critical listening or monitor audio active speakers for a home studio setup, we offer a comprehensive range of products to meet your acoustic needs.

By integrating these acoustic principles with state-of-the-art audio technology, we ensure that your space not only looks and feels great but also sounds exceptional, creating an optimal environment for work, creativity, and communication.