Oh, look studio foam, wrong answer. Acoustics is a vastly complicated topic and big box stores are more than happy to sell you cheap foam which will actually make things worse rather than guide you in the right direction. This is the owner of Spencer Studios, Spencer Miles bringing you audio engineering from the best recording studio in Lancaster, Pa. Todays topic is another discussion on acoustics.
Most of us work in small rooms. I run a small commercial studio and even then, my spaces are small due to the cost of overhead in commercial spaces. My space might be similar in square footage to that of many home producers’ bedrooms, although I am lucky enough to have great 10-foot ceilings. Let’s dive into some fundamental facts of acoustics here. Different frequencies of sound are quite seriously different sizes. If you have never studied acoustics before the idea of sound taking up physical space can be a bit mind boggling. Higher pitches have a shorter wavelength where lower pitches have a longer wavelength. If I were to make a pulse sound that makes all frequencies the human ear can hear at once for them to be equal, you must have room for each sound to make at least have a cycle. This may sound complicated, and I won’t get into phase and cycles today but what I will say is you need an estimated 32 feet of space for 20hz to fit in you room equally to 20 kilohertz.
By this point you are wondering, how can this be? I have heard my speakers produce low sound and my room is nowhere near 32 feet long. The key above is equally. When we put a frequency in a space that it can not fit all spread it gets punched up so that it can still exist. This bunching up or squishing creates pressure build up. Imagine you are coming back from a camping trip. You had a great nights rest in your sleeping bag which fits your six foot two inch one hundred eighty pound self and now its time to pack up. Your sleeping bag which is actually quite large is able to compress down and fit into a pretty small bag but you have to use a lot of pressure to get it in there. This is similar to how a bass note is squished in your room.
Now that we have that out of the way you are starting to realize that bass notes are squished in your room where other frequencies fit freely. The result is that your bass sounds louder than it actually is and when we mix this creates a problem because we can’t accurately interpret the music. The difficult thing is big frequencies require big acoustic treatment. The smaller the treatment in terms of normal porous absorbers the less it does to these bass frequencies. You might think oh I’ll just add a lot of thin absorption and the issue there is you’d just end of soaking up high frequencies making the problem worse. The only ways to truly treat these sub bass frequencies is with a hemholtz resonator or with a diaphragm absorber.
– Spencer, Spencer Studios 313 W Liberty St. Lancaster, PA 17603