To get sound working on CM7 and Absolution ROMS install the bootsnd.sh thru terminal emulator. Also reflashing ROM makes bootani sound not work so every time you flash a new ROM you have to do the bootsnd.sh loading every time. Make sure to see if your phone is storing the bootanimation in system>media folder as well as sound. I have HTC Inspire and my phone stores bootani in system>media. Other ROMS store in system>bin (Most likely Sense ROMs-MAKE SURE BY SEARCHING) MAKE SURE TO MACK UP ROM.
What I liketo do is enter system>media and copy original bootanimation to sd card then save to laptop to keep it saved somewhere.
Thanks to the guys over at Desire HD and EVO Thread
Bootsnd.sh [Just unzip file and place in root of SD Card]
http://www.fileserve.com/file/6jERVaY/bootsnd.zip
1. place [bootsnd.sh] on your sdcard.
2. On your phone, open terminal emulator, and type in the following:
su [hit enter]
cd /sdcard [hit enter]
ls [to see list of all files, you should see bootsnd.sh][hit enter]
sh bootsnd.sh [hit enter]
You won't see a confirmation, or message, it just runs, and returns you to a # sign.
(Back out from terminal emulator then reboot phone to get bootsnd to work)
Then copy sound file to phone>sysyem>media folder.
3. Whatever sound file you use must be .mp3 format and you must rename it [android_audio] it is also recommended for sound not to be longer than 15 sec. What I like to do is when I use a bootanimation I time it to see how long it is and then I edit the audio file to the length of the bootanimation so that they end at the same time. Thou phone will cut off sound on its own at a certain point.
Place the android_audio.mp3 in the system/media folder of phone where bootanimation is.
Reboot, and enjoy your boot sound.
My Bootanimation based on this video
http://www.youtube.com/watch?v=cAyE7IPAm-I&feature=related
My Bootanimation just unzip files on desktop then move to phone and install with es file explorer. No need to rename files.
http://www.fileserve.com/file/WWPrdJw/Transformer Boot and Sound.zip