Transferring iPhone Voice Memos
Best way to do is, is using an cloudsharing app, like Instashare (There are a bunch of them, just search the App store and you'll find a lot of them).

Concidering you'll use Instashare, download the app and set it up. Open your voice memo app and click on the share button. Your familiar share screen will popup. If it isn't listed yet, click on the more button next to Messages &amp; Mail. Enable instashare or any app you want to use, close it by clicking done. Then click yours app its icon. Depending on the app, you have to choose where to place it, but after that it's stored for you. Just now download on you're pc and you're done.

For this method you'll need IOS 8, which is supported for the 4S. Otherwise it'll become really complicated to share it, then you'd better use mail or USB.