Sound and video can improve navigation, user engagement, and flow in your prototype. In addition to that, sound can provide users feedback on their interaction with your prototype. Video can engage users to learn more about the prototype or app.
Sound

Sound enhances usability by giving users feedback on actions they’ve taken. It indicates what a user’s status is within the app and helps users know what they can do next. For example, a notification sound on your smart phone for new text messages. Users can choose to reply or ignore it, but it indeed lets the users know what is going on in addition to the wakeup screen.
Sound increases the user experience because of humans’ emotional responses to sounds. Using sounds humanizes user interactions; as if the app is responding with sound to an action taken. But these sounds should add to or enchance the users’ understanding of where they are within the flow or confirm an action, like a clicking sound after a user taps a button. The different sound for a complete or unsuccessful action to notify the users like the file is failed to upload or download.
Even though, sound foster user experience, it can also be disturbing if the users can’t turn it off. For instance, users might not want any sounds during important meeting or classroom. It is important to give the users the option to turn it off, if they choose to do so.
Video

Video enhances user immersion and creates interest for users as they interact with your prototype. Netflix’s user experience is a great example of video enhancing a design. The opening of Netflix’s app is the feature shows or movie that tie to your previous watch history. It also encourages you to watch content that you might not have otherwise known about or expressed interest in.
Best practice in incorporating video in your design is to make sure that users can adjust volume, playback and pause/stop the video. In addition to that, users should be able to auto-mute the video or stop videos from automatically replaying, if they’re uninterested in the content. More importantly, users should be able turn on/off playing video via wifi or cellular data. Not all users have an unlimited data and playing videos would use a significant of the cellular data.
Lastly, sound and video need to support with accessiblity challenges, too. Any videos and sounds you use should include transcripts and captions, or alternate notifications, to be accessible to all users.
Creating a better user experience
Take some time to think about the different types of users who will interact with your product design. You need to take into consideration of possible advantages and disadvantages of using sound and video. Check out the resources below for more on using sound and video in your design:
- Best Practices For Video by UX Planet
Good Luck!