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Acoustic Materials and Coefficients of Absorbtion
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Studio Design Categories:  Modal Analysis Helmotz Resonators Quadratic Diffusor Acoustic Equations Reports Database Maintenance |
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Studio Design 2010 allows the user to enter in room dimensions of length, width, height
and the reverb response for the room. It calculates all the modal frequencies for axial, tangial, oblique modes
and graphs the results for easy to see modal spacing and mode buildups. While in graph mode, the user can tweak the room dimensions to optimize the modal spacing and build-ups. This is very useful for working within an existing room or planning a new room. When the user is satisfied with the room dimensions clicking the materials option button will show the acoustic materials sabine analysis screen. | ||
Selecting materials by Category
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Studio Design 2010 contains a database of more than 1100 acoustic materials and their respective coefficients of absorbtion. Even better, the user can maintain, edit, add, or delete acoustic materials from this database using the Acoustic Materials menu option. The objective is to add materials one at a time into the grid and enter the area in sq.ft. for that material. Pressing the calc button will update the absorbtion calculations for Sabines and Reverb Time. By watching the Reverb results under each frequency of 125hz, 250hz, 500hz, 1000hz, 2000hz, 4000hz you will see the effect of adding the material. Begin by adding walls, ceiling, and floor materials you will be using and enter the area for each entry. This gives you a baseline to start from. You can then add in other elements like bass traps, helmotz resonators, etc until your reverb totals are at the design reverb time. In this example, RT60 is 0.7 seconds. Selecting a category filters the "Select an Acoustic Material" list. For example, select Walls to see all walls or further filter the list by type. |
Selecting materials by type
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Select type to filter by frequency band of absorbtion such as low, low mid, mid, mid high, high, or wide. When selecting a material from the drop down list, look at the coefficients as well as the current sabine and reverb totals, to pick a material targeted for the current results. After selecting a type, the categories list will update to reflect records assigned to that type. Example: User selects Carpets and can search through all carpets to find one representing theirs, or filter by type to find carpets that have a specific band pattern. Refer to the reverb results. If the reverb time is higher at 2000hz and 4000hz then select a band type with emphasis in the high band. The material list will update and show materials that have coefficients of absorbtion with higher values in that range. |
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Use the acoustic materials sabine analysis to model your current studio, control, listening room or home theater. If its not in the materials database, then find it on the web and simply add it using the Acoustic Materials screen. |
Entering Area of material in Sq. Feet.
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After a material selection has been made, enter the area into the white text field in Sq. ft. and press the calc button. A handy calculator is a click away. Click the calculator icon and it appears. It only multiplies but it does provide floor and wall areas calculated with the dimensions that are currently entered. |
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Example: enter 1025 for area of carpet and calc. The results shows 125hz at 39 is very high in relation to 4000hz at 1.2. Add the walls into the grid. Select Walls as category and low as type. |
Optimizing acoustic materials to achieve desired reverb response
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Look over the different wall constructions and their COA's. Walls really do absorb low frequencies! A common construction is 2 X 6 walls with 5/8" drywall spaced 24" on center filled with 5.5 inches of insulation. |
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Notice how the reverb results change as 2 x 6 walls are added into the grid. Walls were added twice, first time for both length dimensions and again for both width dimensions. The ceiling needs to be entered along with its area. The reverb result can benefit by a low band ceiling. |
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The results show that more low-mid frequency absorbtion is needed to balance the reverb response. Now is a good time to address the Axial mode build-ups to see what low frequency absorbtion is required. Studio Design 2010 provides the ability to design perforated and slat-type helmotz and panel type absorbers and resonators by clicking the Absorber Design menu option. Click on the graph option button  to go back to the modal frequency distribution graphs and look at the axial and all modes graphs. They are shown below and have build-ups (noted in blue) at 43hz, 70hz, and 111hz. |
To address troublesome modes, design helmotz resonators tuned to these frequencies. Helmotz Resonators |
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After designing low frequency helmotz absorbers and adding them into the acoustic materials database, select them from the materials pulldown list and add them into the grid. Add as many materials as you want into the grid, there is no limit. The example above shows how materials can be added and area changed to acheive a balanced reverb response. Save the project and room at any time from the Save Project menu. |
Removing a Material Selection
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Delete a material by selecting the material name in the white left hand field then clicking the Delete icon
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