I have done quite a few audio budgets for games and personally prefer offering outsource sound designers a flat fee for X amount of days designing sounds. This is arranged often a few months in advance of them coming on the project. The reason is that my initial budget proposal has to be complete before the game requirements are clear. It also means I can change what the sound designer will be doing during the time they're working with us - and not have to worry about the cost. This is really important for us as we tend to do really rapid development where the game requirements change by the day. So paying a sound designer per sound or per minute isn't really feasable or practicle.

As an example I once employed a designer to initially work on HUD sounds and a some in game stuff, but after about 2 days everything changed and we decided that they ended up doing music for the game instead. Just because the requiements changed.

Btw I have no idea if this is normal practice it is just the way we do it here ;)

In my experience, it goes one of two ways:

• Flat-fee for entire project
• Daily rate

I've not worked for payment by completed minute before, so not sure if that's accepted business practice or not. Are you working in the US? Or for a company that is based overseas?

If it's a large number of deliverables, I would estimate the amount time required to complete the project and then submit that to the employer to be paid out as a flat-fee upon completion. If it's a small amount of stuff, then daily rate may be the way to go.

There is some tremendously detailed information about billing clients in Aaron Marks' "Game Audio". Although his info is centered around the games industry, I'm sure a lot of the information would apply to sound design contracting in general. Here's a link to the book on Amazon, I couldn't recommend it more.

http://www.amazon.co.uk/Complete-Guide-Game-Audio-Developers/dp/0240810740/ref=sr_1_1?ie=UTF8&s=books&qid=1283322882&sr=8-1