The Importance Of Room Acoustic Treatment

Most of the gear that is been produced these days are easy on the pocket and are of very high quality, that can create A grade music that sounds as if it was recorded in a professional studio or anything that is being played on radio. Many producers, artists are yet unhappy with the quality of their productions and wrongly blame their gear. Without a doubt experience matter but so does having the right acoustics in your room. This article explains the basics of acoustics in a way everyone can easily understand and follow. All of the information present here also applies to audiophile, home theaters or office / school spaces.

Pic Courtesy : Rayi Iyer Music Academy & Studios

Bass In Place: Bass Frequencies are without a doubt the most difficult to tame, especially in small rooms that lot of people use to produce, record or mix their music. The common problem that everyone faces is miss that sounds great in your room may not sound the same anywhere else and could sound muddy or too bassy. The culprit here are the bass waves that bounce off the wall behind you, creating reflections and making deep nulls in the response you hear. 

Since you hear less bass than it really is in the track, you add too much bass with EQ and compression to compensate it. You may have the finest of the speakers in your room but they would be of very little values if your room is bare and reflective. The solution of course is bass trapping. By placing bass traps in the corner of your room, you are able to hear the low frequency response becomes much flatter and tighter and also dips less around the room. A typical rectangle room has 12 corners: 4 where each wall meets another wall, 4 where each wall meets the ceiling, and 4 where each wall meets the floor.

You don't necessarily have to treat all the corners presented above. You will notice a change by just using bass traps to the 4 corners where one wall meets another and you can already hear the difference in your sound.

Pic Courtesy : Apurv Isaac Studios

Room Orientation & Speaker Placement:  In any standard rectangular room, its best to orient the mix position so the speakers are firing the longer way down the room. So its always best practice to not be closer to the facing wall, and have the mix position in between the room.

This improves the response at low frequencies as well as mid and high frequencies, as mentioned above bass frequencies can be very difficult to tame unlike the high & mid frequencies which can be easily tamed by placing acoustic panels around the listening or mix position.

Primary & Secondary Reflections: Another common mixing problems that we face is poor clarity and imaging by the primary and secondary reflections. Sound from the speakers travel directly to your ears but a few milliseconds later, reflections that are bounced of the side walls and ceiling arrive. This is known as comb filtering as in time smearing. 

Comb filtering is a specific type of frequency response error that creates a series of peaks and dips. To tame these frequencies you can treat your room with acoustic panels on your side walls, behind walls and ceiling. Once you have treated these points you will notice a sudden change and can easily hear EQ changes and very small changes in left-right panning.

Beauty Of Diffusion: Diffusion helps avoid standing waves, damaging flutter echoes and comb filtering cause by the primary and secondary reflections off the walls around, while keep the natural ambience and air of the room unlike absorption. 

The best type of diffuser is called a QRD Diffusers, which stands for Quadratic Residue Diffuser (QRD is a patent of RPG). You don't really have to understand the math behind a QRD Diffuser to appreciate the clarity and the sound it brings than any bare reflecting wall.

Unfortunately good diffusers cost more than good absorbers because of the precision and the high end material it requires to be built. If the room and your budget are both small, placing acoustic absorptive panels on reflective wall surfaces works well. But when cost is not an issue then diffusion is the key!

Pic Courtesy : Akshay Rajpurohit Studios

A NO! NO! To Room EQ: If you are trying to use an equalizer to fix the acoustic problems of your room, stop! right there, it does not work! Every location in a room has a different response and no single EQ curve can help you everywhere. 

Even if you are trying to correct the response only where you sit, it is impossible to counter nulls and room modes. If you have a 35db dip at 63Hz, adding boost with EQ will only increase low frequency distortion in the speakers.

At other places where 63Hz is too loud, the EQ makes the problem worse. EQ does reduce peaks by a fraction but it does not reduce the extended decay time that accompanies with most peaks.

Professional Acoustic Treatment = Professional Results: Don't even think of blankets, rugs, egg cartons, non-acosutic foam and carpet! All of the mentioned do not work, its just another Internet myth. Egg cartons are too think to absorb low frequencies which is needed for most rooms, maybe 50 cartons put together could absorb some high frequencies, maybe! On the other hand, non-acoustic foam that is used by the mattress industry or the packaging industry is not suitable because all of the foam mentioned above are closed cell foam, and for absorption you require open cell foam.

Rigid Styrofoam panels that are used for insulation are not much of use but some EPS Diffuser might work in 2000Hz to 5000Hz range. The best Acoustic Panels & Bass Traps are made of high-density fiber boards. Inch for inch, the rigid board absorbs more and to a lower frequency than any other material available.

Pic Courtesy : St. Therese International School

Recording Studios, Home Theaters, Auditoriums, Listening Spaces etc: Acoustics dont necessarily come into play only at professional studios or home theaters. Poor acoustic surrounding can damage ones intelligibility and reflect negatively on the productivity of employees. Most offices, schools, restaurants, call centers use acoustic panels or acoustic ceiling for taking care of the unnecessary sounds in the ambient and increase speech intelligibility. 

Unfortunately most employers think otherwise and try to save up on spending on the acoustics of their offices, board rooms or restaurants. Knowingly or Unknowingly they are suffering a much bigger loss than they actually try to save, but again who is to say?