All settings are stored in the URL. This is updated every time you make a change.
The dBmap.net Noise Mapping Tool is used for modelling external sound propagation and calculating sound levels using sources of environmental and industrial noise and screening from buildings and barriers.
This is intended to be a tool for understanding and implementing the calculations of ISO-9613 and creating interactive models that are freely accessible.
Please read through this guide. You can print this page and you can access it again at any time from within the Global Settings sidebar.
All settings are stored in the URL. This is updated every time you make a change.
Save your model by bookmarking the page or share the link. Click here for more information
The browser back button will "undo" changes.
Any up-to-date web browser. Calculation times will depend on the processing power of your device.
This tool is free to use. Some features are only available when you are logged into a user account with a valid subscription.
The top-right button is where you can access the Global Settings sidebar panel. Here you will find all the options for your model including configuration settings based on the calculation parameters of ISO9613.
In there you will also find the button to open up this guide.
Calculations are automatically run whenever a change is made to the model. You can temporarily pause this process by clicking the top-left button.
To stop these calculations permanently, under Global Settings change Display to "Noise map off".
You can speed up calculations by enabling multi-thread calculations. This will utilise more cores of your CPU for faster processing.
Your model is stored in the browser location bar URL. Bookmark the web page and it will save your model exactly as it is.
Remember to create a new bookmark or update the old one whenever you make any further changes.
Each change you make creates a new entry in your browser history, which means you can undo your changes simply by hitting the back button or going back through the history.
As with saving, you can share the link and other users can view your model exactly as you have set it up at that moment. Their browser may be different and may recalculate at a different speed but the results will be the same.
Click the Short URL button in Global Settings. This will use our server database to store your configuration and automatically convert it to a short URL.
Subscribers can take Snapshots that saves the short URL to their account with a thumbnail of their model.
Users who are not logged-in or do not have a valid subscription will not be able to access the subscription-only features, however any line sources and ground heights that you have added to the model will still be included.
In the Global Settings sidebar there are various Export options:
Generate a PDF of the noise model based on the active mode and current view. Includes tables and charts of receiver levels, spectrums and breakdown of sources.
Download an image of the noise map. Subscribers export higher resolution images. To download the Cross Section, Ground Heights or 3D view, activate this mode first.
Create a comma-separated file to load into spreadsheet software. All objects are detailed in full and each receiver has a detailed list of sources including calculation breakdown.
A ray-receiver illustrates the sound paths considered. These include:
Calculate the difference in level between two configurations of your model. When activated the following options will appear:
Edit the model as usual.
Create a different setup for the objects and settings in the model.
View the difference in level when switching to the alternative scenario.
Object position and ground height topography is fixed and cannot be compared.
Ground height objects are only visible in Ground Height mode.
Ground height is triangulated using the height points and lines. The ground is sloped in locations where only two height points are available.
When "Draw ground height triangulation and screening" is selected in the Global Settings, the resulting ground height triangles are drawn onto the noise map and the edges that can cause screening are highlighted in white.
When placed on sloping ground, the model considers one end of a flat barrier or one corner of a building as the reference point for the height.
When in Ground Height mode each building and barrier has a basic wireframe of the 3D shape to illustrate the difference in height at each point.
Hover over the object and Click the centre point to shift the reference point to the next available location.
Cross Section mode allows you to slice through your model and see the vertical location of objects.
Points within the 1m capture area 1 and objects that intersect the section line 2 will be shown.
Click the line to reverse the direction 3
Control the cross section height by dragging the top edge of the pop-up window.
Dragging either side of the window will rescale the cross section noise map.
eye icon will show the projection of all objects and sound rays.
The noise map icon will toggle displaying the horizontal noise map height.
Click on the following to quickly set the cross section to fit:
View your model in 3D space in a pop-up window
The Compass indicates the direction of view. Click to reset the view orientation.
Rotate the view either with the set direction buttons or Click and drag the window using your mouse.
Navigate from the main area using the Pan tool or by repositioning the 3D view centre point. Alternatively, use the right button or arrow keys in the pop-up window.
Toggle displaying the horizontal and vertical noise maps.
Receptors (e.g. sound level meters) measure the "sound pressure level" (Lp), a decibel value of the sound by a source at a distance.
The source of sound itself is calculated with a "sound power level" (Lw). This is a decibel value that represents the total acoustic output radiated.
They both contain frequency and amplitude information, but the difference is that a sound power level does not include distance information.
If you have a distance included with your decibel level, the decibel figure may represent a sound pressure level. You can use this to calculate the sound power level using the following calculator.
If you have only a single decibel figure for your sound power and it is for a broadband source, put it in at 500Hz as instructed in ISO9613-2.
The scope of ISO9613-2 only covers the octave bands 63 Hz to 8 kHz. The 31.5 Hz and 16 kHz octave bands are not officially supported by ISO9613-2 but are made available in the model for use, utilising the parameters of the adjacent octave band where necessary.
Useful for modelling sound sources that are not consistent, the Leq or "equivalent continuous sound level" is a single value that represents the equivalent amount of energy in a given period for a fluctuating source as if it were a steady continuous noise level. For this reason the Leq is always accompanied with a reference to the length of time that it represents.
The Lmax is a maximum level (based on the standard time-weightings: fast, slow or impulse) and is useful for modelling the peak of a noise source, such as a vehicle pass-by.
For a point source, sound radiates in a sphere and the "sound power level" represents the total sound energy. A line source radiates as a cylinder along the section lengths and the sound power level is usually considered by the sound energy per metre of length. Therefore, the sound power values are different to a point source and are not directly interchangeable.
When the model calculates a line source, it breaks the line into segments with a point source at the centre with a level proportional to the length of this segment. Use a ray-receiver to inspect this behaviour.
Sound propagation is affected by variations in meteorological conditions. Below are suitable conditions taken from ISO9613-2.
For more information about the calculations and their limitations, refer to ISO9613 parts 1 and 2.
It is essential to consider that modelling is only ever an estimate and real-world measurements may differ greatly.
The following table of accuracy is taken from ISO9613-2 based on tests without screening or reflections
|Average height of source and receiver
|Distance between source and receiver
|0 - 100m
|100m - 1km
|0 - 5m
|5 - 30m
Computer modelling requires a simplification of real-world conditions into basic components. For each simplification there will be a degree of error added to the model. It is recommended that you highlight where these simplifications have taken place.
When enabled, lateral paths around vertical edges are found within a flat plane inclined along the direct source-to-receiver line.
The lateral path method can be configured to only consider "convex" paths that curve in a single direction and do not zig-zag.
ISO17534-3 recommends that lateral paths are limited to vertical edges within the range of the most distant horizontal edge multiplied by 8, with respect to distances from the direct source-to-receiver line. In complex models, applying this recommendation will improve calculation times considerably.
ISO9613-2 considers the effect of edges that are not screening, for example an observer looking over the top of a wall. This model only accounts for such a situation along the top edges. Vertical edges are only considered when you are in the shadow of the barrier.
It is recommended to use a ray-receiver to inspect vertical paths and decide yourself the importance of these diffracted levels. Read here for more information on using the ray-receiver
Sound waves will be reflected or absorbed by the ground depending upon the frequency of the sound wave and how porous the ground is (indicated by the "Ground factor" value G). The barrier attenuation formula also accounts for ground effects.
Insertion of a screening barrier will reduce the level of a source using the formulae of ISO9613-2. The guidance states that this reduction in any octave band is limited to 20dB in the case of a single screen or 25dB for multiple screens.
You may want to disable this limit to see what effect it has on the final levels.
Following the method in ISO9613-2, a barrier is only considered to be screening if the horizontal dimension perpendicular to the source-to-receiver line is greater than the wavelength.
You may want to disable this check to explore the unusual effect it causes. For example, as you move around a barrier its apparent width in your field of vision decreases. There will be a point where this width drops below the wavelength of the source and the barrier will no longer be considered to be screening.
In the formulae of ISO9613-2 (1996) ground effects are removed by the insertion of a barrier. However, ISO17534-3 (2015) recommends that only negative ground effects are removed - i.e. attenuation due to ground absorption.
When "Do not screen ground reflections" is selected, any increase in level due to ground effects will not be affected by barrier insertion, as is recommended.
Raised ground levels will behave as a barrier when breaking the line-of-sight between source and receiver. Read here for more information about inspecting ground level screening
Screens with a reflection coefficient above 0.2 are considered to be reflecting and the model will include these reflected sources in up to two screens when First and Second reflections are enabled in the settings. Barrier attenuation along the reflected path is also considered up to the height of the reflecting screen.
Only barrier and building sides make up the reflecting surfaces considered. Reflections from the roof of a building are not considered. Ground reflections are part of the ground effect calculation (ground factor).
ISO9613-2 provides the following estimates of the sound reflection coefficient:
This is the reduction in level applied to the original sound level based on the chosen reflection coefficient.
A "facade level" measurement is one taken at 1 metre perpendicular distance from a large reflecting surface. It is an industry practice for measurements that can be later adjusted to a free-field measurement, one that is outside of the range of influence of reflecting surfaces. The behaviour of reflections at less than 1m from the facade are not accounted for.
By enabling this all buildings and barriers will show a dashed line illustrating the 1m facade location. Reflections are only considered at distances beyond this line. Additionally, receiver points will be kept outside of this area when being positioned.
For a surface to be considered as reflecting, the size of the surface is compared to the wavelength of the sound using a formula that also considers the angle of incidence and sound path length. This formula can be found in the guidance.
You may want to disable this check to see the result when reflections are always considered for a vertical surface regardless of its size.
The model is free to use for both private and commercial use but without any warranty.
This is an approximate calculation tool to assist in understanding acoustics and noise mapping (sound level modelling).
It should not replace your own calculations and real life measurements.
The settings of the model are stored in the URL. This is loaded from our server when you or someone else first loads the model from the URL and each time the URL shortening service is used. As the settings are stored in the URL, anyone with access to the URL will have permanent access to these settings.
Google Analytics is used to track page visits.
We may sometimes use information about the general activity of the model to improve the service but we treat all modelling activity as confidential and will not pass this information on to third parties.
The User Subscription service stores your account settings and library (snapshots, color schemes, sound levels and images) in our database. This data is never made available to other parties or used for any purpose outside the use of this tool by the registered account. You control this data and can remove it from within your account at any time.
Browser cookies are used for accessing your User Account. We do not use them for anything else.
The calculations are done client side, this means that they are not stored anywhere online but are generated by your computer each time you access the page.
All the objects and settings are saved in the URL.
Images are referenced by their URL or filename.
It is important that you do not reference images that breach license, copyright or legal restrictions and that you understand that the model will no longer have access to the image if it is removed.
They are not automatically stored on our servers and are only temporarily cached on your computer when generating the model.
Local image files can be uploaded to your User Account to become accessible to others when you share the URL.
Use this tool to select and move objects.
Note: You can also use the arrow keys to move around the model
Note: You can also zoom using the scale-bar on the left of the screen or with your mouse wheel.
This is a source of noise that radiates from a single point and in all directions in a spherical shape.
A line source radiates sound in a cylindrical shape. The line source will be modelled parallel to the ground level.
This is an acoustic screen that can attenuate a sound path and reflect them, such as walls and solid fences.
It is not currently possible to model floating barriers or ceilings.
To draw buildings with more than four sides, use the Add Barrier tool.
These are the same as barriers except that internal walls are ignored and the area within is not calculated.
Sloping roofs can be added to any buildings with four parallel sides. All other buildings have roofs that are flat and perfectly horizontal.
Reflections are not considered from the roof surface.
The building height is relative to the ground height at the first point. More information can be found in the guide
This is a marker where the total decibel noise level is calculated at the specified height along with an optional frequency spectrum graph.
All sources of noise will have lines drawn directly to these receivers to indicate sound propagation paths or "rays".
When showing waves, the wavelength is drawn to scale.
When showing rays, the dashes represent different frequency bands.
These lines can be used for measuring distances or simply for illustration.
You can also convert between accessory lines and other objects.
When rotating, hold the Shift key to constrain to right angles
This defines the ground height at a point and is used for triangulating ground topography and creating slopes.
This defines the ground height along the line and is used for triangulating ground topography and creating slopes.