# OnEventStopped doesn't trigger after sounds completion + Banks performance **URL:** \ **Category:** Unreal Engine\ **Tags:** ue4\ **Created:** [August 9, 2023, 6:50am UTC](https://qa.fmod.com/t/oneventstopped-doesnt-trigger-after-sounds-completion-banks-performance/20515 "2023-08-09T06:50:01Z")\ **Posts on this page:** 2\ **Page:** 1
**Author:** ![Kautrr](https://avatars.discourse-cdn.com/v4/letter/k/b9e5f3/32.png) [@Kautrr](https://qa.fmod.com/u/Kautrr)\ **Post date:** [August 9, 2023, 6:50am UTC](https://qa.fmod.com/t/oneventstopped-doesnt-trigger-after-sounds-completion-banks-performance/20515/1 "2023-08-09T06:50:01Z")
Am I suppossed to do anything special for the OnEventStopped to trigger when the sound is done playing? I start my sound by Play Event Attached and after it’s done unfortunately this event is not triggered. Second question is about the banks, what is the best approach? Should I make a seperate bank for every sound to prioritize performance? If not because this will make a bit of a mess in a project, how many sounds should I use per bank? I understand that it probably depends but I would appreaciate some type of guidance. ---
**Author:** ![Leah\_FMOD](https://yyz2.discourse-cdn.com/flex036/user_avatar/qa.fmod.com/leah_fmod/32/3685_2.png) [@Leah\_FMOD](https://qa.fmod.com/u/Leah_FMOD)\ **Post date:** [August 10, 2023, 4:25am UTC](https://qa.fmod.com/t/oneventstopped-doesnt-trigger-after-sounds-completion-banks-performance/20515/2 "2023-08-10T04:25:25Z")
Hi, > [@Kautrr](#): > > Am I suppossed to do anything special for the OnEventStopped to trigger when the sound is done playing? I start my sound by Play Event Attached and after it’s done unfortunately this event is not triggered. The most likely cause of this would be that you haven’t ticked [“Enable Timeline Callbacks” on the FMODAudio Component](https://www.fmod.com/docs/2.02/unreal/user-guide.html#callbacks). It could also be that your Event has not reached its natural end, either because of a lingering audio signal (e.g. reverb, delay effects), because you have additional timeline logic in the future that has not executed, or because the event is set to be persistent. > [@Kautrr](#): > > Second question is about the banks, what is the best approach? Should I make a seperate bank for every sound to prioritize performance? If not because this will make a bit of a mess in a project, how many sounds should I use per bank? I understand that it probably depends but I would appreaciate some type of guidance. I would recommend against creating a bank for each event in your project - besides your choice of which events to assign to a bank, FMOD will handle a lot of the optimization around banks at runtime for you, and offers API functions if you want specific bank loading behavior. Banks are comprised of audio sample data, and event metadata, the latter of which is comparatively small as far as memory goes. Unless you specify otherwise, when loading a bank FMOD just loads the metadata, and will only load a given event’s sample data when you create an instance of the event. For more information, please see my reply here to another user asking a similar question: > [@Is it possible to load a Bank from an EventInstance or EventReference?](https://qa.fmod.com/t/is-it-possible-to-load-a-bank-from-an-eventinstance-or-eventreference/20389/4): > > If you weren’t aware, by default audio data isn’t actually loaded into memory when you load a bank - instead, the data is loaded on-demand when an event instance is created. You can choose to manually load audio data for an event or an entire bank ahead of time if you need to as well, which is useful for events with a large amount of audio data, and/or when you need to play events with sample-accurate timing. I would recommend reading our documentation on [Sample Data Loading](https://fmod.com/docs/2.02/api/studio-guide.html#sample-data-loading) for more information. > > The expected workflow with FMOD is to have a broad knowledge of what sounds you need played at any given time in-game, as this typically informs both how you sort/group individual events into banks in FMOD Studio, and which banks you load at a given time in-game. For example, you may know that for a given level you’ll only need a specific set of events; therefore, you create a bank for those events, and only load it for that level. > > If you have no idea which banks you’ll need loaded ahead of time, it may be worth planning them out to see what events will be needed where. Alternatively, you may choose to load many or all banks at once, and only load the sample data as needed. Ultimately, it depends on your project, of which you’re the best judge. If you have any further questions about how bank layout and loading work, feel free to ask.