the acoustic characteristics of space
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The Acoustic Characteristics of SpaceTRANSCRIPT
The acoustic characteristics of space There are three main musical spaces that are used in music recording and live performance which I will be talking about in this article. These are a recording studio, a music venue and a theatre/auditorium. Each musical space needs to have specific treatment depending on what the space is being used for, the size of the space you are working with and you will need to take into account standing waves, absorption and reverb time. Music Studio Firstly, in a music studio the purpose is purely to record music. This means you will want it to be a sound proof room with effective acoustic treatment fitted. An ideal design of a studio space would be to have an outer wall and an inner wall with absorptive material (such as carpet) on top or in between. I would suggest using carpet all around in the studio both the floor and the walls) so that sound energy is absorbed. This will allow sound energy to be diffused and absorbed into the wall which stops it being reflected back into the room. When working with any glass panels, it would be best to make sure they are doubled up with one pane of glass at a slight angle which prevents standing waves as there will not be any parallel sides. It would also be good to have a very thick door to also add to the acoustic treatment as sound proofing. It would be useful to have a Helmholtz resonator which is a piece of wood with small holes in which also absorbs the sound energy. Aim to get quality chairs in a studio space so there is no squeaking from the chairs/stools which would interfere with recording.
Venue
Secondly, in a music venue the main purpose is purely for people to perform music which means that the surrounding environment and materials used for the space must be suitable for live performances to sound good. The walls should be made from concrete and plywood. This is because the materials used do not need to be as absorbent as a recording studio space. You need to consider the dimensions of the room, the overall volume of the room, the total surface area and the absorption coefficient (how much sound energy is absorbed by the room). The average absorption coefficient of the venue we measured was 0.38. In a venue that measures 14.76m in length, 9.18m in width and 3.33m in height it results in the overall volume of the space as 451.29m³. The resulting RT60 (which is the reverb time and the time it takes for an audio signal or sound energy to reach -‐60dB) is 0.6 seconds. The average absorption coefficient of the venue we measured was 0.38.
The screenshot above is called the amroc room mode calculator. This gives you a visual representation of all the modes within the room using the room dimensions to work out where the modes are in the room. The diagram also shows the frequencies of the room which is done by spectral analysis. Theatre Furthermore, another main musical space is a theatre. This is slightly different as they are not often purely used for musical performances so there is more difficulties when it comes to the acoustics of the space, acoustic treatment and sound absorption. You could easily transform a theatre so that it has the correct acoustic characteristics and treatment for sound and live performance. This can be done in the same way you would do this for a venue as mentioned in the previous paragraph except there are more aspects to think about such as the ceiling is usually higher, there is more on the ceiling (for lighting and effects) and the seats are stacked up in layers. All of these aspects have an effect on the acoustics of the room and the overall sound of any music performance. Other aspects to consider Any musical space, regardless of its purpose, needs to have the correct acoustic treatment. When working with a space, you need to work ou t the reverb time (RT60) and the absorption coefficient (how long it takes for the sound energy to be absorbed) so you know
the characteristics of the room. As I mentioned in the recording studio section of this article, a studio space has to have proper sound proofing so that there is no interference in recording. One problem, however, is that most studios have a live end and a dead end effect where the engineer/producer will have the absorptive features but the clients behind them at the back will have more of the ambience of the room. If there is too much ambience in the control room of a studio (liveliness), it will cause problems when it comes to trying to mix a track properly. Another aspect of acoustic treatment that could make a big difference is the position of speakers. You will want your speakers to be in the best position as possible so the intended audience can hear the sound properly. The monitor speakers in a studio should be placed at an angle with one speaker on the left and another on the right. Try to avoid placing your speakers up against a wall or a corner if the bass port of the speaker is at the back because if this is the case, the wall will absorb all of the bass of your track when it is being played causing problems when you mix a track. This applies even in a recording studio inside a control room because an engineer/producer will need to be able to hear the sound to find and fix mistakes, to mix properly and edit a track effectively. The same applies for a client as the client will want to hear what their song sounds like. If the speakers are not positioned correctly, then you will end up with a poor mix as you would not have been able to hear it properly in the studio. The same applies for PA speakers in live performance in the venue and the theatre. Acoustics and acoustic treatment is all about frequency. This means within a room you can use spectral analysis, as I mentioned under the room mode screenshot, to work out the frequencies within a room. You can also use a graphic equaliser to change some of the frequencies in a performance to help it sound better in a room where there may be standing waves or where there are many unwanted frequencies. All the aspects mentioned in this article must be taken into account when designing a musical space whether it is a studio, venue or theatre space because the whole purpose is to achieve fidelity in any environment depending on its purpose.