Home Studio Acoustics: Part 2

     In the last post I discussed home studio acoustics and ways to improve the quality of your listening environment.  In this continuation I will talk about home studio sound isolation solutions to help keep sound from leaking into your neighbor’s place.  First, the basics of sound isolation.  Sound will ALWAYS find a way through openings.  Any opening, big or small, will let sound pass through.  Sound will also travel through the structure of the wall by vibrating the surface and passing those vibrations to the opposite side.  Three things happen when sound hits a surface.  Some of the energy is reflected, some is absorbed, and some is transferred.  We have already covered reflection and absorption, so onto transference.

    The most obvious place to start is at the door.  The quality of the door is going to make a huge difference in the isolation of the room.  Hollow core doors will let more sound through while solid core doors will absorb and reflect more.  So if you can, try to buy a nice solid door.  The next step is seal around the edges of the door.  You can buy standard seals from a hardware store and install it along the jamb of the door.  When the doors closes it will create a nice seal.  Next is to get a threshold seal for the bottom of the door.  Something along the lines of a standard bubble seal should suffice.  This will stop sound from escaping under the door.  

     

     Next is to find other places where sound can get into the wall or outside of the room.  Such locations include power outlets.  By taking off the faceplate you will notice a gap between the back box and the drywall.  Placing some sealant in this gap will stop sound from escaping.  So where else can sound get out?

     If you have a drop ceiling then chances are sound is escaping from there.  Special acoustic ceiling can be purchased that will not only increase the isolation, but the absorption as well.  If you can’t afford ceiling tiles then placing some insulation above the ceiling will work too.  Now just keep looking for places where sound can escape and do your best to seal up those exits.  Many people have asked me how to improve their walls.  If you have think walls that are bad at isolating sound, then it is best to rebuild the wall to be more resilient.  Using dual layer drywall or mass loaded vinyl is an excellent way to improve the performance of your walls.  Gaps in the fiberglass insulation can let sound through so using sprayed insulation will drastically improve your performance.  It will also save you money on the heating bill!  If you live in an apartment and can’t open your walls to fix them, then there isn’t much you can do.  The best solution is to try and place absorption and diffusion on the wall to catch as much sound to keep it from transferring through the wall.  Keep in mind that more absorption will alter the acoustics inside the room so use with caution.

    

     This concludes the two-part segment on home studio acoustics.  Stay tuned for future posts that will revisit some things in more detail.  Please do some research on your own and familiarize yourself with basic small room acoustics.  It will really help you during the treatment process.  Thanks for reading!

-Jon    

Home Studio Acoustics: Part 1

     We already know that home studios are not going away.  It is best to embrace this shift in the recording industry and figure out a way to make it work.  Many professionals criticize homes studios because they are often run by amateurs, and they don’t necessarily use the best equipment or have the best acoustics.  Recording and mixing music is all about the acoustics.  If the acoustics of the space are decent then low grade equipment can still be useful.  However, bad acoustics can make even the best equipment completely useless.  This two-part blog post will overview some effective ways to strengthen your room’s acoustics and give you a better mixing environment as a result.  In this first post we will go over some ways to treat the inside of your room.

     Let’s assume that for this post that you live in a space where knocking down the walls and building from scratch is not an option.  This is probably the most realistic scenario.  So what do you do?  Well, you have to treat the room in such a way that you eliminate reflections and room resonances.  However, sound isolation is also very important if you live in an apartment building and have neighbors.  Sound isolation techniques will be covered in the second post so let’s focus on reflections and resonances for now.  Small rooms are very tricky to deal with because they produce room modes within the audible frequency spectrum.  A room mode is the natural resonance frequency of a room dimension.  The equation is the speed of sound/wavelength.  The wavelength in this case is the dimension of the room.  So if our dimension is 19ft, then our resonance frequency is 1130/19=60Hz.  This means that we will have issues within the 60Hz area and some multiples.  

     These resonant frequencies will alter your perception of the mix and this can result in unbalanced mixes.  Reflections are another key component to small room acoustics.  Since the dimensions are shorter the reflected sound arrives at the listening position with strong amounts of energy. This too can alter the perception of the mix and cause phase issues.  So let’s talk about some effective ways to treat these issues.

     After figuring out the frequencies that are giving you trouble you can begin to pick out some acoustic treatments.  Companies like Primacoustics and Auralex provide some affordable consumer grade acoustic treatments that can get the job done.  Don’t just slap foam all over the walls though.  Place some absorption directly on the wall behind the speakers and at early reflection points to eliminate sound reflecting off the walls towards your ears.  Next, it is wise to pick out some diffusion to place on the wall behind the listening position.  This will help scatter the sound around the room so it does not create a standing wave.  A cost effective way to create diffusion is to use furniture elements like a book shelf filled with books.  The various depths and densities of each book create a great diffusion element with some absorption as well.  

     Everything I have discussed so far is great for mid to high frequencies, but we know that low frequencies are what’s giving us the most trouble.  Low frequencies like to hangout in corners so placing high density objects there can help absorb some low end.  The companies mentioned before also sell some corner bass traps to help with this problem, but it is not necessary to spend a lot of money.  You just have to understand basic acoustics and absorption properties.  Many people will say to place egg cartons on the wall for diffusion and absorption.  This is not a good technique.  Egg cartons do provide some absorption, but it is only in the high frequencies.  We know that small room suffer most from low frequency issues, so egg cartons aren’t the best solution.  

     This ends this installment of home studio acoustic basics.  Next post I will discuss sound isolation methods for your home space.  Future posts will revisit the acoustic treatment topic so stay tuned. 

-Jon