Panel & Room Properties

Panel Size

The size of the panel can affect the measured sound transmission loss. Small panels have a low radiation efficiency at low frequencies and so appear to have a higher TL than larger panels of the same material. INSUL predicts this effect using an expression developed by Sewell. In INSUL the adjustment is called as Sewell's correction. This correction is normally turned on and the panel size is set to 2.7 × 4.0 m.

Note that because window systems are almost universally tested at a smaller area (and thus have a larger TL at low frequencies), there is a separately defined area for glazing systems (when you have selected Glazing from the construction type options), by default, this is ~ 3 m² and as a reminder it is displayed on the Glazing input page.

You can set different panel sizes in the Settings window.

Sewell's Correction can be turned off from the Settings window.

Edge Damping

Along with Sewell's Correction, Edge damping can be turned on and off from the Settings window.

Room Properties

The receiving room volume and reverberation time can also be entered into the dialog box on this form.

The receiving room volume and reverberation time are required for calculation of rain noise when sound pressure level is the selected ouput.