Turns out this problem was with another program called AudioJack. It interferes with QEMU and prevents sound from working. Uninstalling AudioJack made the AC97 sound card work again under Mac OS 10.6.
** Changed in: qemu Status: New => Fix Committed -- You received this bug notification because you are a member of qemu- devel-ml, which is subscribed to QEMU. https://bugs.launchpad.net/bugs/1246890 Title: AC97 sound card crashes QEMU Status in QEMU: Fix Committed Bug description: The AC97 sound card does not work. It stops QEMU on startup. The cause appears to be some kind of deadlock. Steps to reproduce: Just add -soundhw ac97 to QEMU's arguments. Example: qemu-system-ppc -soundhw ac97 The example above is all it takes to reproduce the problem. This problem has been observed on Mac OS X and Debian Linux. I question whether the ac97 support ever worked. It is a file that was taken from VirtualBox and added to QEMU. I do know that VirtualBox's support for the ac97 sound card works perfectly. The exact line of code that stops QEMU in its tracks is located in the file main-loop.c, in the function os_host_main_loop_wait(), the call made to qemu_mutex_lock_iothread(). The is where QEMU stops under Mac OS X. To manage notifications about this bug go to: https://bugs.launchpad.net/qemu/+bug/1246890/+subscriptions