So technically the terms Sound Card and Audio Interface could be used interchangeably. But for our discussion let's define Sound Cards as hardware internally mounted to your computer, while a studio Audio Interface is an external hardware unit connected via USB or FireWire.
Unearned revenue is money received by an individual or company for a service or product that has yet to be fulfilled. Unearned revenue can be thought of as a prepayment for goods or services that a person or company is expected to produce for the purchaser.
Examples of unearned revenue are: 1  A rent payment made in advance. 2  A services contract paid in advance. 3  A legal retainer paid in advance.