Launch the Calm, then the icon appears in the status bar at the top right of the desktop. To display the infomation panel or settings panel by clicking on the icon. If you are connecting a device to the headphone jack, the setting of the volume of the device will be as same as the settings of the Calm. If the Mac startup sound is increased by connecting the device to the headphone jack, please disconnect the device of the headphone jack. Then install the Calm. You startup sound can be set.
[Note] If OS X 10.7, the feature of the Calm is enabled after second restart of the Mac.
Can be set up the startup sound volume and the standard sound volume.