General Features
All sound calculations meet international ASTM E90, ISO 140, ASHARE-1987, Sound Research Laboratory,…etc Calculates the required silencer attenuation to meet noise criteria  Verifies any selected silencer to meet the noise criteria  Design acoustic wall or partition to meet certain SRI or certain noise criteria Change the wall or partition steel thickness, acoustic filling properties and perforation geometry and see the effect on the noise attenuation Takes into consideration free field and reverberant rooms situations. Design rectangular attenuators by allowing you to flexibly adjust all design parameters such as overall aperture size, number of splitters, splitter thickness, air gap between splitters, acoustic filling acoustic properties, perforation sheet configuration, air way length, air flow, flow velocity,…etc Takes into consideration inlet air temperature and temperature rise inside enclosures. It differentiates between inlet and discharge air sound attenuations by considering the regenerated noise.  It calculates pressure drop across all air inlet and discharge attenuation systems. Design acoustic louvers by allowing you to flexibly adjust the louver depth, louver blade shape, louver blade thickness, air gap between blades, louver depth, louver acoustic filling properties and perforation sheet. It allows also adjusting the free area percentage and air flow velocity. It will provide the insertion loss for the designed attenuator and sound transmission loss for the louvers. The software helps to calculate the best perforation that can achieve best acoustic results. The software can estimate diesel engine exhaust noise, surface noise and air flows if not known. The software calculates any noise in free filed or inside reverberant rooms either as a single noise figure or over the octave band. The software is equipped with a tool to calculate the wall or partition SRI The software is equipped with a tool to calculate average room absorption coefficient over octave band. The software is equipped with a tool to calculate pressure drops for different duct configurations and elbows. Click here to get more information and obtain a quote
Exhaust Noise Silencing and Calculations
This design sheet enables to do either do the exhaust noise calculations to find the optimum exhaust silencer attenuations (dB's) at all 8 frequencies or if you have a silencer with known dB's you can verify if it suites your diesel engine. Of course you have to define a criteria such as 90dB at 1 m or 85 dB at 3 m and so on. You have to have the engine exhaust noise SPL or SWL data from the engine manufacturer. If not known to you you can use the exhaust noise estimator which is part of Acostix 2010 to get the engine exhaust noise.   If the engine is inside a room or enclosure with reverberant characteristics then you need to enter the room dimensions. To be much more precise you need to enter the average sound absorption coefficient of the room internal walls. If not know to you you can use the absorption coefficient calculator to find them.   At the end the software will give you the results and summary of all calculations. You can always hide or show these calculation for the purpose of submittal to your customers.
Enclosure Wall Design and Calculations
This design sheet enables you to either design an acoustic wall. This means to find the sound reduction index (SRI) of the wall or to verify certain wall if its SRI is known against noise acceptance criteria. This wall could be enclosure wall or building room wall.   You need to have the engine service noise SPL and you have to enter the room or enclosure dimensional details. To design the wall you need to select the wall materials and thicknesses. You need to enter the acoustic filling materials sound absorption coefficients and its thickness. This is available from the manufacturer data sheet. Also you need to select the perforated sheet thickness and configuration. If not known to you you may use the tool available in Acostix 2009 for this purpose.   The results will be displayed as SRI data required to achieve the noise criteria or as noise level using the known SRI.
Inlet/Discharge Attenuators Design & Calculations
This is a powerful design sheet which does two things at the same time. It designs the rectangular attenuator by finding its dimensional parameters and acoustic characteristics to achieve the noise attenuation from one side and it also gives the dimensional parameters that achieve maximum allowable pressure drop across the attenuator air ducts.   The sheet can do 4 functions: design inlet attenuator, design discharge attenuator, verify inlet attenuator and verify discharge attenuator.   You need to enter the engine surface noise SPL data, air flow data, noise criteria, overall aperture height and width and then you select the number of air ways and the thickness of the splitters. Of course there are rules how to select them which you can learn in our noise attenuation design course. You can fine tune your selection to get the best results of acoustic and pressure drop performance. You can always select to show or hide the detailed calculations. The sheet allows you to select the acoustic materials filling details and enter the average room absorption coefficient which can be calculated by Acostix 2010.
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Acoustic Louvers Design and Calculations
Similarly this design sheet enables to design the acoustic louvers to achieve the required acoustical and air flow performance. You can select either to design inlet or design discharge louvers. You can select among 5 different louver shapes.   You have to enter the engine surface noise SPL. You need to enter the selected acoustic filling materials absorption coefficients and thickness. You need also to select the perforation configuration. You have to specify the noise criteria and distance. You can select if the room is reverberant or not, and accordingly enter the absorption coefficient data, which can also be calculated by Acostix 2010 tools.   Then you can choose your design parameters. Louvers blade thickness, Louver depth, louver blades spacing and free area percentage of the overall aperture.   The software will display the resultant noise and air pressure drop for the selected design. You can fine-tune your design parameters to optimize the results. Of course you can select to show or to hide the calculations before you print the report.
Cover Sheets Perforation Configurations and Calculations
This tools enable you to find the Transparency Index (TI) and the open area percent of the perforated sheet used to cover the acoustic materials used in air ducts. These two parameters affect the acoustic performance of the perforated sheet and therefore affect the overall acoustic performance of the air duct assembly.   Of course the higher the TI the better it Will be for the noise absorption of the acoustic filling but this may not be possible due to the perforation sheet mechanical characteristics and strength.   You enter the perforation geometry and the sheet will calculate the TI and P. These two parameters are inputs to the design of the walls, attenuators and louvers.   The resultant of this sheet are the TI, P and the access factor which will be multiplied by the absorption coefficient of the acoustic material. In other words this access factor downgrades the acoustic materials sound absorption capability.
Engine Exhaust Noise/Surface Noise and Air Flow Estimator
This tool enables the designer to estimate the engine exhaust noise SPL or SWL, engine surface noise SPL and the inlet and discharge airflow.   You just enter the engine KW and then select from the drop down lists different characteristics of the engine which must be known if the engine is physically available.   The software will display the engine exhaust and surface noise data over the 8 frequencies and the inlet and discharge air flow. This results can be used to design walls, attenuators and louvers if the data is not available from the manufacturer.
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Free Field Noise Calculations Tool
Sometimes you may need to calculate the noise in the free filed if the noise is knows at some location.   This sheet allows for noise calculations of SPL or SWL at different distances in the free field. You can either do the calculation for a single dB figure or over the 8 frequencies.   SPL vs SWL:   The difference between SPL and SWL: SPL is the sound pressure level =20 log P/Pref.  P is sound pressure in N/m2 and Pref = 20 x 10-6 N/m2, while SWL is sound power level = 10 log W/Wref, where W is sound intensity in Watts and Wref = 10-12 Watt. The sound is is coming out from the source as SWL and when it travels spherically its intensity will be distributed over sphere area which makes it pressure SPL
Inside Rooms (Reverberant) Noise Calculations Tool
You may also need to do calculations of noise inside the room if the noise source is placed at certain distance and you need to measure noise at certain point inside the room taking into consideration the reverberation time of the room.   This sheet does this. You can do this as a single figure or you can enter the noise data of the source in SPL or SWL over the octave band, and enter all other details of the room.   The resulting information will be the noise level at the point you selected. You can select to show or hide the calculations before printing the report.
Wall/Noise Barriers Design and SRI Calculations Tool
This sheet will calculate the overall SRI of an acoustic wall or barrier which can consist of doors and windows.   The sheet enables you to select the windows and doors dimensions, Windows glass and thickness configuration.   You need to enter the wall, door and windows dimensions. Then the sheet will calculate the overall SRI of the assembly. This SRI can then be used as a known SRI value to complete the wall design for enclosure or rooms as stated in wall design sheet above.
Average Room Absorption Coefficient Calculations Tool
This tool helps designers calculate the room average sound absorption coefficient over the octave band.   The sheet allows to enter the room dimensions, and from the drop down lists one may select the side wall, end walls, roof and floor material.   The results of this sheet will be the average absorption coefficients and the reverberation times.   These results are very valuable when calculating sound from inside rooms through walls, attenuators and louvers
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Pressure Drop Calculator Tool
This sheet helps gives the pressure drop across different duct systems which you may choose from the drop down list.   It helps when sometimes the inlet air or the discharge air needs to be ducted 45 degrees or 90 degrees for some distance.
Help Screen and Assistance
This help tool can answer many of your questions about the software design sheets and tools. You can select your question from teh drop down list and the answer will be displayed in front of you from the help database.   However if you have a question which has no answer in our database you feel free to contact us at: support@najahengineering.com
Cost of the Acostix 2009 Software
You can choose to purchase the complete software or you can select the design sheets according to your business needs. Please complete the Acostix 2010 inquiry form and submit. We will send you our best offer within two business days.   The software is sold with one complete day of free training and setup plus free upgrades of the software within 1 year from the date of purchase.   The software is a copy righted material. It will be licensed to the purchaser as a single user and it shall not be copied to a third party for any reason without a written permission of Najah Engineering Consultants LLC.
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