This mod needs to be applied with the xdelta patcher, which can be found here:
https://www.romhacking.net/utilities/598/

Simply apply the patch "RHUndub.xdelta" on an unmodified USA rom and you're good to go!

If you want to use this patch with another Romhack (I.E Touchless): 
- Use a tool (such as DSBuff) to UNPACK both your romhack of choice AND your patched Undub roms
- Copy the sound archive file (located at "data/soundarc/RIQ.sdat") from your UNDUB unpack folder
- Place it in the same location in your ROMHACK unpack folder
- Use a tool (such as DSBuff, it can do both!) to REPACK your Romhack unpack folder
- Play your new Romhack file!

DSBuff:
https://www.romhacking.net/utilities/1214/

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NOTE:

There is only one, TINY thing about this romhack that is inaccurate to the JP version, and that is the JP exclusive "Down" voice clip that plays along with the ball spawning cue in Remix 9 and in Space Soccer's practice doesn't play, even with this patch. I'm not even sure that most know about this JP exclusive sound cue or care that it's not included, but I figured I'd be upfront. Hopefully that's not a deal breaker for ya :P

More info here:
https://tcrf.net/Rhythm_Heaven/Regional_Differences#Remix_9