JB seem to have an option to suppress notifications for each app, but for ICS that does not seem to be possible.
I was forced to make up a solution myself, so I started to locate the notification sound and was able to find them in /mnt/asec/com.ea.game.simpsons4_row-1/pkg.apk
All which has to be done now to sleep easy, is to remove the .mp3 files from the apk. To do that you need root access:
# mount |grep simpson
/dev/block/dm-22 /mnt/asec/com.ea.game.simpsons4_row-1 vfat ro.dirsync,nosuid,nodev,relatime,uid=1000,fmask=0222,dmask=0222,codepage=cp437,iocharset=iso8859-1,shortname=mixed,utf8,errors=remount-ro 0 0
Now do (while using the path and device information you obtained above):
umount /mnt/asec/com.ea.game.simpsons4_row-1 mount -t vfat -o rw /dev/block/dm-22 /mnt/asec/com.ea.game.simpsons4_row-1
If you cannot unmount and get a message like:
failed: Device or resource busy
The next step is to copy the file pkg.apk to a destination of you choice (e.g. /mnt/sdcard/).
Open the file as zip with Total Commander or any other program able to zip/unzip apks.
Now navigate inside the archive to the folder "res/raw" (Total Commander will show in the location bar "/mnt/sdcard/pkg.apk/res/raw")
You should now see a lot of mp3 files.
If you are as much a Homer fan than I am you should extract those files and hear them before you delete them all. My favorite: "Are you cheating on me with another game"
Ok back to the subject:
Select all mp3 files in this folder (pkg.apk/res/raw) and delete them.
Now you can copy the file pkg.apk back to the game folder, overwriting the original one.
You will still get the game notifications, but they are silent.
I expect that this procedure has to be repeated after an update of the game.