Acoustic within "eigenmodes of a room"

Hi,

I need some help in comsol.

I am working in the default project "eigenmodes_of_room" and created an additional "normal velocity" boundary with 0.1 inward velocity. Then i added an "impedance" boundary, set the "impedance model" to Absorption Coefficient and set the Absorption Coefficient of the ceiling and walls to 1 to simulate a non-reflective boundary. In the end i added a study 2 frequency domain.

Here my questions, i guess rather understanding-the-program-better-questions:

1. Since the sound pressure level plot in the results shows me dB-values from ca. 50 to ca. 120; what is the exact velocity of the initial sound wave? Is it 120 dB at all frequencies?

2. How can I exchange the "normal velocity" boundary with a "plane wave radiation"/"spherical wave radiation" boundary? Im getting no results when Im doing this.

3. Is it possible to configure the initial sound wave (normal velocity boundary) to for example 50 Hz with 80dB, 200 Hz with 74dB, 500 Hz with 83 dB etc? So a specific loudness for every single frequency?

4. Since I can define the impedance of specific boundaries - How is it possible to assign a material on a boundary (wall in the model) which has specific material properties, e.g. the absorption coefficient at 1000Hz = x, etc?

Best,

Adrian