在 http://developer.android.com/guide/topics/ui/notifiers/notifications.html有这个注释:

注意:如果 defaults 字段包含 DEFAULT_SOUND，则默认声音会覆盖声字段定义的任何声音.

Note: If the defaults field includes DEFAULT_SOUND, then the default sound overrides any sound defined by the sound field.

所以，如果你只想自定义声音，你可以使用 -

So, if you want to customize only sound, you may use -

notification.sound = Uri.parse("android.resource://" + getPackageName() + "/" + R.raw.notifysnd);
notification.defaults = Notification.DEFAULT_LIGHTS | Notification.DEFAULT_VIBRATE;