This app calculates the combined sound pressure level at a specific location in a room, starting from mounted devices with given sound power levels and taking the sound absorptions and reflections of walls into account.

The absorption coefficient of a wall is a value between 0 (=total reflection) and 1 (=total absorption). The app offers three options to enter the absorption coefficients:
1. You select a typical room from a list and use its predefined absorption coefficient. Each room has a specific value for the ceiling, the walls and the floor.
2. You enter an absorption coefficient for each wall of the room, using the published values for the materials used on the walls.
3. You enter absorption coefficients for a standard set of sound frequency values: 63Hz, 125Hz, 250Hz, 500Hz, 1000Hz, 2000Hz, 4000Hz and 8000Hz. The sound absorption may differ for each of these frequencies, depending of the materials used on the walls. These absorption values are also published by the manufactures of materials.

The devices either supply or extract air. You mount them in rows and columns in any wall of the room and define their sound power level. You have two options to enter the sound power level of a device:
1. You enter a single sound power level value for the device. This value is expressed in dB(A). A dB(A) value is a weighted dB value, taking the sensitivity of the human ear into account.
2. You enter sound power values for a standard set of sound frequencies values: 63Hz, 125Hz, 250Hz, 500Hz, 1000Hz, 2000Hz, 4000Hz and 8000Hz. These values are expressed in dB or dB(A). The app converts dB values into dB(A) values.

The app then uses the position of a human head as the target to calculate the distances from each of the devices and the corresponding sound pressure level for each of them. Finally, it combines the results from the devices into a global result for the room. Depending on the data entered, the result is a single value or a set of values for the standard set of sound frequencies.

These results are displayed in overviews next to a 3D representation of a room with a human figure. It also visualizes the distance from a device to a human head. The final step is the creation of a pdf-report with the data entries and the calculation results.

Features
- Manage projects defining a room, walls with absorption coefficients and devices with a sound power level, mounted in a room ceiling, wall or floor.
- Create a scrollable onscreen report of the results or a corresponding pdf-file.
- Choose between metric or imperial unit dimensions, e.g. m and ft.
- Select one of the five languages (English, French, German, Spanish and Dutch) in the preferences screen.
- Tap the explain tab to get a short explanation of different steps.
- Supports light and dark themes.
- The app saves your latest settings and starts up with those settings.
- Adapts its user interface when you rotate your screen.
- Zoom in (two fingers gesture) and pan (one finger gesture) to enlarge and move a part of the screen.
- Uses the available virtual keyboard and makes sure the keyboard does not cover the data entry field. However, when using a GBoard keyboard, use its floating property to move the keyboard freely over the screen.