Sometimes, we want to adjust the acoustics of a room to make it sound either more reverberant (wet) or less reverberant (dry). This involves manipulating the amount and type of sound reflections within the space to achieve the desired audio quality. Absorbers and diffusers are great tools for these purposes.  ## Absorbers It is often desirable to make a room more dry because excessive reflections can color the sound in an unwanted way and cause microphones to capture excessively wet audio, which is harder to work with in post-production. It is easy to add reverb but generally more difficult to remove it. By reducing reflections, you can achieve a clearer and more accurate sound recording, free from the distortions and muddiness that excessive reverb can introduce. Absorbers work by using materials that effectively capture and dissipate sound energy. Common materials for this purpose include acoustic foam, rockwool, and fiberglass insulation. Acoustic foam, with its porous structure, absorbs sound waves and reduces reflections, making it effective for high and mid-frequency sounds. Rockwool and fiberglass insulation are denser materials that can absorb a broader range of frequencies, including lower frequencies that are often more challenging to manage. These materials are commonly used in bass traps, which are specifically designed to absorb low-frequency sounds that tend to accumulate in the corners of a room. ![[image-2.png]] Absorptive Coefficients: https://theandrewsgroup.com.au/sound-absorption/ ### Placing Absorbers By strategically placing these absorptive materials in a room, you can significantly reduce unwanted noise and reverberation, creating a clearer and more controlled acoustic environment. This setup is crucial for recording studios, home theaters, and other spaces where sound quality is paramount. If you recall, first reflections are the sounds that occur after sound bounces once. Remember that sound spreads in all directions, so when a sound bounces off a surface, it is actually bouncing in many directions, creating even more reverberation. By isolating the spots where the first reflections occur (the first reflection points), you can essentially nip any further reflections in the bud. Watch the following video to see how to accomplish this. ] ## Diffusers Diffusers achieve the opposite effect of absorbers. Instead of absorbing sound waves to reduce reflections, diffusers scatter sound waves in multiple directions. This scattering helps to break up standing waves and reduce the perception of "boxiness" in a room, which can be caused by parallel surfaces reflecting sound back and forth.  By breaking up and spreading out the sound waves, diffusers create a more even distribution of sound energy within the space. This results in a livelier, more natural acoustic environment without adding excessive reverberation. Diffusers are particularly useful in spaces where you want to maintain a sense of openness and spaciousness while preventing the build-up of problematic reflections. They are often used in combination with absorbers to achieve a balanced acoustic treatment. ![[image-3.png]] Diffusers can look quite beautiful! Here is an example of a skyline diffuser. The patterning is very specific, and there are precise calculators used to determine the placement and height of the different segments. [QRDude](https://www.subwoofer-builder.com/qrdude.htm) is one such tool. ![[image-4.png]] ## Anechoic Chamber An anechoic chamber is a space designed to have nearly no reflections. It is so well treated that all reflections are nipped in the bud, creating an environment of profound silence. It is actually eerie to be in one because it is so quiet that you can hear the beat of your heart and other subtle sounds of your body that are usually masked by ambient noise. This unique environment is often used for testing audio equipment, conducting acoustic experiments, and measuring sound with extreme precision. Watch the following video of a balloon popping in an anechoic chamber. It will give you a sense of how much reflections actually factor into our perception of sound. ] ## Resources There are several excellent online resources for information on how to treat a room for optimal acoustics. SoundOnSound magazine has some outstanding articles, such as [this guide on monitoring acoustic treatment](https://www.soundonsound.com/techniques/studio-sos-guide-monitoring-acoustic-treatment) and [this beginner's guide to acoustic treatment](http://this%20beginner’s%20guide%20to%20acoustic%20treatment). Additionally, Gearspace.com is a valuable source for acoustic treatment information, where the community is willing to help. A good thread to start with is the [Acoustics Treatment Reference Guide.](http://Acoustics%20Treatment%20Reference%20Guide)