ACOUSTIC DESIGN
Jorge Castro, 32 years old, born in Fafe, Portugal, Studied Sound Engineering at Porto’s Polytechnic Institute (IPP) ; MSc/Pg in Audio Acoustics at Salford University, Manchester; co founder of Vicoustic, currently working as Project/Product Manager and in I&D for the company. Jorge also lectures at Evora University.
Jorge explains some of the fundemental principles behind acoustics and the problems encountered in treating a studio monitoring environment; and some of the solutions to these issues in order to create a high quality listening environment.
“Why do people buy acoustic products? For sure there has to be a reason for investing in sound control products, and that is simply the need to take the best out of our sound systems in our rooms. But in fact, the main question we should be asking is … why does sound need to be controlled anyway? This question will take us in the next minutes into a journey of sound characteristics and its behavior, especially those occurring inside an enclosed room, whether it is a Studio, a Home Cinema or even an Opera theatre.
Although people may not have conscious of the science facts behind sound, the truth is that most of us have already got into a place where we said or thought: “Such an awful sound in this place”, and we’re not talking about music styles… we’re talking about getting into a room and just knowing that there was something wrong with the sound of it, whether it is long echoes or simply confusing sound. This happens because sound is just like a light from a lamp in a room with a window. The path the light takes is not just the straight line between the lamp and the surface that’s in front of it (whether it is the floor or a wall), instead, light covers the whole free space of the room and even goes into other rooms through the window. So it is with sound. Whatever may be its source, sound will fulfill the whole room in all directions and even fly into other rooms through the floor, ceiling or walls, since sound waves can travel by any solid, liquid or gas material. Well, acoustics is simply the way sound is affected by the physical properties of the space where it is being produced, and this is why clients want good acoustics and therefore why acoustic products companies develop materials that will interfere with the physical properties of the space, so that in the end, we all come up with rooms with adequate distribution of sound, ensuring clarity of speech and “completeness” of music.
When considering the properties of a room, what we’re really trying to avoid are acoustic defects such as: Strong reflections, flutter echoes, reverberation and standing waves.
Keep up with us and we’ll show you, how each one of these things occur in your own room, preventing you to benefit from the full potential of your sound system. Fortunately there are solutions and we’re also going to show them to you!
Low frequency – Standing Waves
Resonating waves, usually occurring on low frequencies, represent the acoustic phenomena of sound waves that are exactly as long as the dimension of the room, or in half proportions of that (other standing waves happen in parallel of the original one). Resonating waves are louder and take longer to disappear and therefore generating more confusion especially when we consider that are at least 6 surfaces in a room.
I believe 90% of the room’s problems are related to lack of low frequency control. A typical home studio is usually small, and the smaller the room, the higher the low frequency limit (lowest frequency with resonant support). These spaces are prone to:
- Significant modal resonances
- Too much spacing between modal frequencies
Example
- 3m long room – bass limit of 56 Hz
- 6m long room – bass limit of 28 Hz
- Above 300 Hz the modal frequencies are so close together that problems associated with lower frequencies disappear.
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