Custom Flash Cards Sound

Is it possible to add sound to custom flash card sets? 

I don't think so, there doesn't seem to be any button to add sound.

Seems to be the case. I've started using tinycards from duolingo.  The program is free and and you have the option of it voicing the card and although it is a computer generated voice, it is not too bad. I find it helps to hear it at the same time you look at it, otherwise I start hearing it in my mind differently than it actually sounds.

I use that too, it really helps.

Duolingo has now decided to discontinue tinycards. I'm prorting those cards over to the Rocket Flash cards but still wish I could find one that does the sounds. Anyone know of any place I can get that?

To answer my own question I found a free program called Anki. It is open source and has a sizable user community. For me there was a bit of a steep learning curve to get it to work the way I wanted it to but after watching a few videos and carefully reading portions of the manual I was able to get it to do what I wanted. For sound there are a couple of options. You can use the built-in language sound files in your computer. With this option you can get it to work like tinycards  although with my Windows 10 built in sounds they are a little mechanical sounding.  You can also use also link mp3 files to a card. It is more work to do it this way but the results are better. One advantage with doing it this way is you can have just the sound file play for the front of the card and then set it so you have to type in the word on the back of the card. 

If you use the free Audacity media program you can make clips from the Rocket dialog mp3 files to use as the sound file. Other good sources are FORVO which allows you to download mp3 files of native speakers. For a very nice sounding and accurate synthetic voice I find Natural Reader to be very good and it has the ability to speed up or slow down the voice without affecting the pitch which is nice. With Audacity you can pretty much make a sound clip out of anything you can play on your computer. So you can take dialog from movies for example to use with your flash cards. So I'm happy to have this now - I really think I learn much better when I work with sound and text together.

I've used Anki before and I agree it's a good app. For German, DeutschAkademie is also helpful, although I've not checked to see if it has a sound option.