Ahh, okay....so you do only want to COPY the file FROM your Smartphone, to your computer.
This is quite simple. But I understand we are not all the same technical level.
So, the best way to do this is with a Cloud Drive.
Connect the smartphone to the WiFi, and get a cloud Drive, like Gdrive (Googles cloud drive offering) or OneDrie (Microsofts cloud drive offering) I recommend Gdrive. YOu should be able to download it from the App store on the smartphone.
Once you have the drive on your phone, move the Audio file to the Gdrive, and give it some time to upload.
Then go to the computer and again get Gdrive downloaded and installed.
Keep in mind that Gdrive uses your Google account. So make sure you are using the same account to login for Gdrive on both devices (Smartphone and computer)
Or, you can try usng a LARGE FILE TRANSFER EMAIL SERVICE.
YouSendIT is an application that works from your Android phone as well as on the web. You will receive 2GB of storage. You can upload any kind of file as long as it isn’t bigger than 50MB. There is a 50MB file size upload limit for YouSendIt. When you want to share a file, there are a couple of options. The first is using any of the options on your phone. You may have already shared a file via MMS or email, this option is the same.
When you need to share a bit more information than a file or picture, you can share a whole folder. What’s cool here is, you can choose whether they can just Read the files in the folder or Read and Write to the folder. Reading and Writing is great for groups. When you share a folder, you will email the recipient an invite to access the folder.