When discussing venues with artificial sound sources such as recording studios, churches, pubs, auditoriums, or home theatres, the topic of room acoustics often arises. However, it’s important to note that the treatment of acoustics is necessary for any venue with artificial walls and hard surfaces like tiles, concrete, or other materials. In scientific terms, if a place has reflective surfaces, acoustics correction is needed.
Every living creature is naturally attuned to a specific acoustic environment. Humans and other creatures adapt to their living surroundings, like cave-dwelling creatures being accustomed to the reverberant environment of a cave. These creatures may even use the phase shifts of arriving sounds with reflections to identify potential threats.
So, what is the purpose of acoustical correction in a room? It’s all about creating a comfortable atmosphere, akin to the coziness of your own home.
During the construction and interior designing process, various materials and furniture equipment are used. These materials possess different characteristics, such as being glossy, matte, rough, soft, or hard. These acoustic characteristics can significantly impact the overall acoustics of a room. By properly treating any venue, you can create an environment where people feel comfortable and relaxed, even during extended periods of stay. When you combine a sound system with a properly treated room, you’ll enjoy the ultimate listening experience. In fact, even a low-budget sound system in a treated room, such as a studio, auditorium, or home theatre, will outperform an untreated room equipped with expensive top-of-the-line equipment. Additionally, the comfort of good acoustics in your coffee shop or restaurant can naturally attract more customers, eliminating the need for expensive marketing campaigns.
Common acoustic problems
In the realm of acoustics, certain issues tend to arise frequently. These problems become more pronounced in spaces with numerous reflective surfaces in a confined area, such as small rooms, narrow passages, low ceilings, or tiled floors and walls. Conversely, over-absorption of sound, caused by an excessive presence of sound-absorbing materials like curtains, sofas, or absorption panels, can also lead to poor acoustics. As we have previously discussed in our articles, it is essential to control reflections and manage the reverberation time within a space.
Let’s delve into the most common acoustic problems and explore potential solutions:
- Flutter echo
Flutter echo often occurs in areas like passages and spaces with low ceilings. It is characterised by the repetitive bouncing of sound between two walls. A simple clap can help identify flutter echo by producing a distorted sound accompanied by a series of reflections. Unlike a typical echo that is heard after a brief delay, flutter echo lacks a clear echo but consists of a series of echoes along with the original sound. The best treatment for flutter echo is diffusion, which involves altering the direction of reflected sound away from the direction of the arriving sound, thereby mitigating the issue.
- Comb filtering
Arrival of the same sound with different sources at the same time will cause a phase shift between two signals.
When the same sound arrives from different sources simultaneously, a phase shift occurs between the signals. This phenomenon, known as comb filtering, results from the overlapping of a sound with its reflected signal. Comb filtering manifests as a series of cancellations and boosts across the frequency spectrum, adversely affecting the tonality of the sound. Properly controlled acoustics can eliminate comb filters within a space.
- Roomy sounding spaces
If your podcast studio or recording space produces a “roomy” sound, indicating that your recordings or podcasts reveal the small size of the room, it signifies a lack of absorption in the lower frequencies and low mids. Since lower frequencies have longer wavelengths, they tend to resonate and create a ringing effect within the room. Addressing this issue requires implementing adequate absorption in the lower frequency range to reduce the room’s reverberation.
- Room modes
Room modes pose unavoidable challenges, particularly when working with low or bass sounds in a space. They arise due to the dimensions of the room and result in a series of standing waves. Axial modes, tangential modes, and oblique modes are the three types of room modes that lead to cancellations and boosts at specific frequencies within the room. While room modes cannot be completely eliminated, identifying areas with excessive boosts or cancellations and avoiding those spots can help minimize their impact. Helmholtz resonators are commonly used to address room mode issues.
Soundproofing vs Sound Absorption
It is crucial to differentiate between soundproofing and sound absorption. Soundproofing aims to isolate a space from external noise and prevent sound leakage, while sound absorption pertains to the materials and their ability to absorb sound energy within a specific space. Although the objectives differ, the materials used to achieve both soundproofing and sound absorption can overlap. For instance, Rockwool is a widely popular material for both soundproofing and absorption purposes. It is important to consider parameters such as Sound Transmission Class (STC) and transmission loss for soundproofing, and absorption coefficient for sound absorption.
DIY techniques for improving room acoustics
For spaces primarily used for general conversations or higher-frequency sounds, arranging furniture, incorporating wall and ceiling decorations, can improve acoustics by approximately 80%. However, in spaces with empty walls, reflective surfaces, or glossy decorations, it is advisable to undertake proper measurements and consider additional measures such as acoustic foam panels. While most DIY techniques focus on addressing higher frequencies, lower frequency issues may require industrial solutions. Popular DIY concepts include using curtains, sofas, cushions, or even egg cartons, which can be fairly effective in tackling higher frequencies. For those with carpentry skills, attempting to replicate industrial solutions such as Helmholtz resonators, Quadratic Residue Diffusors (QRDs), or corner traps at home could be a possibility.
By understanding these common acoustic problems and exploring suitable DIY techniques, you can enhance the acoustics of your space for optimal sound quality and comfort.
