​When placing speakers, you need to know how far a single speaker can deliver sound.

The sound pressure decreases the further away from the speaker.

​Of course, this range increases as you turn up the volume.

​Although it depends on the application, to ensure that the broadcast content is delivered to the listener, the minimum sound pressure should ideally be 10 dB above the surrounding noise. BGM can be lower in volume.

​Another thing to consider is the maximum sound pressure a person can tolerate hearing. It depends on the environment, but generally anything over 90 dB spl is probably a harsh environment.

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​In other words, the blue area in the left diagram, sandwiched between the minimum sound pressure and the maximum sound pressure limit, is the actual service area of ​​a single speaker.

​Note that if you turn up the volume on an amplifier or other device, the light blue range will expand, but the red range will also expand.

It is not a good idea to install speakers in a way that places people within the red area, but as long as the red area is above people, there is no problem.
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Some TOA family data have the ability to display this range as radial "sound rays."

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From here on, it will be explained how to operate it in Revit.

Place the speaker in the 3D view of the project and enter the angle in "Angle". Then check "Sound Pressure" to display the sound ray.

First, enter the maximum sound pressure value that is the limit in "Desired SPL (dBspl)" to check the range of the limit sound pressure. In this example, 90 dBspl is entered. Then check whether the sound ray touches the human ear. If it touches the ear, enter a negative value (dB) in "Attenuation." This is equivalent to turning down the volume on an amplifier.
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Then, enter the minimum required sound pressure in "Desired SPL (dB spl)". The position of the tip of the displayed sound ray will be the range that the sound pressure will reach.

Please note that the sound pressure is not the same along this sound ray. The desired sound pressure is only at the tip of the sound ray, and the closer you get to the speaker, the greater the sound pressure.

The data can be downloaded here.