Bear with me… I’m not a musician.  I am helping a local theatre with a production of Shrek. 

In short, they would like to have “fart” and “burp” sound effects to play in a song. 

Ergo… it needs to burp and fart on beat.  Can this be done with the Yamaha S90-xs?  Recommendations?

You can’t with the S90XS. Use a sampler instead, or a Motif series workstation starting from Motif classic up.
Alternatively you migt use an audio/MIDI sequencer such as Logic, Digital Performer or Sonar to play back audio chunks in time.

To help and answer your question there are tons of possibile solutions, but if you don’t have somewhat little technical background is like trying to empty the sea with a spoon.

Kinda what I figured.  Thanks!

Seems like overkill to purchase something else when you already own an S90 XS. While the advice given you is true, the S90 XS does not have a sampler but it does have the ability to playback AUDIO directly from a USB Stick or AUDIO stored on its internal 192MB internal memory.

I assume a musician will be manning the keyboard during the performance and can access the data as required (on cue).

You could create the data (we’ll leave that up to you as to whether you use authentic sound effects or you get creative)… but assume you have the sounds available in .WAV or AIFF format. (16-bit/44.1kHz)

That is all you need - you will create a “SONG” for each. One could be named for each bodily function. It will not so much be a song but an event on the S90 XS Sequencer Chain function.

The S90 XS can read .WAV files or AIFF files (that are 44.1kHz, 16-bit), directly from a source.

The S90 XS has a SONG CHAIN function that will allow you to store these “events” (albeit they are going to be one event each) on a list, you can even program the sound so that it plays when you press the PLAY button… it will then advance to the next cue and wait. When you need the next sound, press the PLAY button again for the next sound effect… it will advance to the next cue and wait… and so on.

While, true, this could be handled a bit more elegantly on a Motif XF (where you could place the samples in a DRUM KIT and simply press the key when desired) I just feel that purchasing a Motif XF (as much as that is a highly recommended synth when you need a sampler too) just to make these sound effects, is a bit overkill. Yes, it could certainly do the job… but since you already own an S90 XS, we felt we should offer an alternative to spending more money.

How to program your .WAV to a SEQ PLAY Chain:
• Press [MULTI/SEQ PLAY] button to view the “SEQ PLAY” chain screen
• Highlight a location (there are 100).
• Press [ENTER] as if you were going to ADD A FILE to a SeqPlay position for real time play
• You will be shown a list of connected drive devices: INTERNAL and whatever you have connected to the unit via USB. Notice the USB drive is numbered (means you can use a HUB of drives)
• Select the “Internal” ROM or the USB Stick that contains the .WAV and press the [>] cursor arrow to see a list of files/folders on this device
• Highlight the file you want to work with > press [ENTER]

This will add the .WAV to that slot on the list.
In the following slot use the DATA WHEEL to enter a “STOP” command. This will cause the SEQ CHAIN to advance to the very next slot and await your next command.
In the next slot - add the next cued Shrek-effect - we assume that you can follow the script as necessary for the performance and map out your bodily function Shrek-effects, as necessary.

You can customize this as you require. If your very FIRST slot recalls an S90 XS MULTI - the keyboard performer can have it choose as many as 16 Voices for immediate access (They will be accessible via the [1]-[16] buttons while the Chain function does its thing)… so they can play along musically and add the Sound Effects via the PLAY button.

This may or may not be ideal but at least worth exploring before spending money… let us know if we can help further.

Thanks Bad_Mister

Your point of view and your reply opened me a new perspective.

I can endorse this - I have played live show with audio effects on cue exactly as described.