No sound in Flash with aa-enabled firefox

During the flash plugin initialization, flash tries to access "${HOME}/.asoundrc" if this file exists.
But access to this filed is blocked by AppArmor, which makes alsa initialization fail :

access("/etc/asound.conf", R_OK) = -1 ENOENT (No such file or directory)
access("/home/xxxxxxx/.asoundrc", R_OK) = 0
stat("/home/xxxxxxx/.asoundrc", {st_mode=S_IFREG|0664, st_size=86, ...}) = 0
open("/home/xxxxxxx/.asoundrc", O_RDONLY) = -1 EACCES (Permission denied)
write(2, "ALSA lib conf.c:3419:(config_fil"..., 40) = 40
write(2, "cannot access file /home/xxxxxxx"..., 42) = 42
write(2, "\n", 1) = 1
write(2, "ALSA lib conf.c:3339:(snd_config"..., 45) = 45
write(2, "function snd_config_hook_load re"..., 70) = 70
write(2, "\n", 1) = 1
write(2, "ALSA lib conf.c:3788:(snd_config"..., 43) = 43
write(2, "hooks failed, removing configura"..., 36) = 36
write(2, "\n", 1) = 1

Access to this file is authorized by "/etc/apparmor.d/abstractions/audio":

owner @{HOME}/.asoundrc r,

But denied by "/etc/apparmor.d/abstractions/private-files", which has priority:

deny @{HOME}/.*rc mrk,

"/etc/apparmor.d/firefox" calls "/etc/apparmor.d/abstractions/audio" directly.

"/etc/apparmor.d/firefox" calls "/etc/apparmor.d/abstractions/abstractions/ubuntu-browsers.d/firefox" which calls "/etc/apparmor.d/abstractions/abstractions/ubuntu-browsers.d/java" and "/etc/apparmor.d/abstractions/abstractions/ubuntu-browsers.d/user-files", both of which call "/etc/apparmor.d/abstractions/private-files".

Removing the "${HOME}/.asoundrc" reactivate sound in flash. But it's hard to guess.