Unit 1: Acoustics For Musicians - Acoustic Treatment

Unit 1 Acoustics For Musicians

Acoustic Treatment & Room Design

Live Room - A good live room should provide a clear and concise sound but should also be homely and inspiring, so an artist feels comfortable and gives their best performance. Use of soft furnishings in a live room not only gives a homely feeling to the performer allowing them to relax and give a good performance, it can also provide absorbtion of frequencies and reflections of frequencies in different directions, which could help shape the sort of sound the producer wants to achieve from the recording. Artists and producers often have specific ideas of how they want their recordings to sound, so live rooms have to be diverse to allow for this. To create a diverse live room you can install special panels which reflect sound on one side creating natural reverb, and open out so broadband absorbing panels absorb the sound waves creating a very dead space. This is useful in recording as a band may want to capture the vibrancy of a group performance and therefore want the recordings to sound good without post production being applied to them, in which case they'd use the reflective panels to create this lively sound, whereas if the producer wanted to record nothing but the sound of an instument without any room characteristics being applied to it so they can alter the sound after recording then they can opt to turn the panels around so they're absorbing sound waves and preventing reflections of sound waves altering the sound that's recorded. Another characteristic of a live room is that it needs to be spacious so microphones can be placed around instruments and drum kits, but not so large that delay problems occur between individuals playing together, as often in a large reflective space the reverb can deceive performers into thinking they're playing in time when they're not. Sometimes live rooms are split into sections by moveable screens which give independent spaces to each performer and their instruments, but allow them to play as a group. This is useful as it helps to prevent spill between microphones, which can cause problems in the mixing process. For example, if the drum cymbals can be heard on the lead guitar recording, whatever effect is applied to the guitar will be added to the cymbals that have spilled onto that track, and this could mean that you end up giving the cymbals horrible properties that you only wanted to apply to the guitar.

Here's a picture of the live room at Rimshot studio in Kent. This quote from their website explains what they wanted their live room to be like:

"Although the acoustics of the room are all-important, at Rimshot we believe that how you feel is just as important to getting the best performance.We wanted to create a space that felt both informal yet really special; where musicians are able to relax but are also inspired to give their all and do their best work."

These beliefs are enforced by the use of rugs which are homely but make moving instruments like the organs easy, to create the layout a group wants, and warm lighting which creates and nice environment to work in. Their studio is constructed from an oak frame which they say gives this room its own unique character which cannot be easily replicated. This is a clever insentive to get groups to use their studio as they may find that they experience a great chemistry working in this environment and subsequently decide they want to do all their recordings in this unique space. It's also important that the shape of the roof and the timber cladding and frame are designed so that they create the optimum sound quality. They will be placed in patterns which scatter the sound waves as they hit them, acting like diffusers which means that sounds aren't reflected back to the source and creating a false illusion of a certain sound property.

Control Room - The control room is where a producer and sound engineer will mix and apply effects to each track of a multi track recording. In this process it's crucial that they're hearing a true reproduction of the recorded sounds, and that room properties or errors in room layout and equipment being used isn't decieving them into thinking something needs altering when it doesn't. There are some basic rules to creating the correct environment to mix in, and if they're all stuck to then you can create a mix that will sound correct anywhere on any reproduction system. Firstly, it is suggested that sitting facing lengthways is better when mixing, as it allows for better bass performance as the wavelength of low frequency sounds is longer and needs more space before hitting a surface. Also it helps if the room isn't a cube shape with parralell walls, as this promotes phase cancellation, which is where reflected sound waves meet other sound waves and the peaks and troughs of the two waves cancel each other out, giving the illusion of an absence of that sound, when infact the properties of the room have meant it just appears to be missing, but even if your control room is this shape there are ways of prevent this problem with skyline diffusers which are made of blocks of different heights and shapes hung on the walls and cielings which brake up the sound waves and reflect it off in multiple directions, meaning it isn't heading back to it's source and causing cancellation. It also helps to have broadband absorbers at mirror points around the room to abosrb signals and prevent reflections near your seated position that could make a certain frequency band sound too prominant in a mix. An absorber is a sheet of rockwall which can vary in thickness depending on what frequencies you want to absorb (if not all) with a space between it and the wall which is to save money as sounds cannot escape but you don't have to buy twice the amount of rockwall. These are most importantly placed at mirror points on the wall, which is the first place a sound from the monitor can reflect. They're also placed around the whole room to stop secondary reflections and so on. It's recommended not to have speakers too close to the corners of your room as this can excentuate the bass, and you may ending up taking too much bass out of your mix because of this, but if space is a problem many monitors provide a solution with a switch on the back to combat the overcompensation and give a more accurate sound. It's suggested that speakers are mounted on recoil stabilisers as well, which are stands with thick layers underneath them so the speaker doesn't vibrate and gives them more mass so they work more efficiently.  There are also suggestions of how to be positoned in relation to your equipment and the room itself when mixing. It's suggested that you sit so you are one point of an equalateral triangle with the two speakers, and not to sit right in the middle of the room but to sit 1/3 down the room so any phase cancellation that hasn't been adressed doesn't affect you too much.
 

Here's a picture of a typical recording studio's control room. This shows things I've mentioned being used like diffusers and absorbers as well as positioning of equipment and furniture.

Concert Hall - For this section I will focus on the arcitecture and construction of the bridgewater hall and its large performance hall as I feel it's a good example of a well equipped and planned concert hall. Firstly the entire building itself is constructed out of moulded concrete which gives it mass and density which is beneficial to the acoustics of the concert hall it contains. Also the floor of the concert hall is suspended from the foundations of the building so exterior vibrations which could compromise the acoustic balance of the hall cannot affect the sound going on in the concert hall. It has large suspended sheets of glass facing back toward the performers, which cleverly allow the musicians in the orchestra to hear more clearly what they're playing in among a large orchestra. This is greatly beneficial to their performance as they're less likely to make mistakes in the security that they can hear themselves and their contribution to then overall sound of their section and the entire orchestra. As the venue hosts more contempory acts as well as orchestras, it needs to have equipment more commonly assosciated with rock venues, like a large PA system, monitoring and mixing equipment. These are housed in what the venue calls an "acoustic void" above the concrete ceiling so they don't compromise the detailed acoustic properties that have been created in the space below. The overall purpose of the bridgewater hall is to provide the optimum sound quality for whatever sort of act are playing, as in that venue the sound is far more important to the typical audience than the usual concert focus of having everything very loud and dancing around. They want to create a great depth and dynamic range which compliments the sound of any acts, especially the orchestras that depend so much upon the mix of each section making the overall sound right.

Here's a picture of the bridgewater taken from the stage where and orchestra or performers would be positioned. It shows the clear glass pieces hung from the cieling to refelect what the individuals play back to them so they hear themselves in a large and often loud orchestra, helping them stay in time and give a good performance. It also shows wood cladding on walls at the top floor, and on the balcony's which give the venue a warm natural sound, and create a nice environment visually.

Room Data Analysis - Control Room

I wanted to determine how suitable my room would be to use as a control room giving what requirements are needed for a successful control room, and how much treatment my room would need to create such an environment. To do this I put the dimensions of my room and information about the surfaces into an Acoustics Analysis website which would give me information on the rooms acoustic properties, allowing me to make amendments to the room from the information. A link to the website I used is below:

http://www.atsacoustics.com/page--Free-Online-Room-Acoustics-Analysis--ora.html

Here are screenshots of the data I input into the website.

This data was processed and gave me a report suggesting how my room would perform with different frequencies of sound being played when treated with 4 fabric panels that act as sound diffusers. It also suggested an optimum reverb time for the use of my room which is a listening environment for mixing a track or a standard control room, and said where my room would be adequate and wouldn't along the frequency spectrum with these panels added. The results of this are the screenshot below:

This report told me that my room performed well in the low mids between 250Hz and 500Hz but didn't have an optimum reverb time for frequencies above 1000Hz. This means that as higher frequencies have less energy than lower ones, I'd have to set reflective panels at the first point of reflection from my monitors at the hight of the tweeter to reflect these signals giving them a greater resonance to match with my lower frequency sounds.