diff -Nru pulseaudio-13.99.1/debian/changelog pulseaudio-13.99.1/debian/changelog
--- pulseaudio-13.99.1/debian/changelog	2020-10-16 05:23:31.000000000 +0800
+++ pulseaudio-13.99.1/debian/changelog	2020-12-15 16:35:15.000000000 +0800
@@ -1,3 +1,13 @@
+pulseaudio (1:13.99.1-1ubuntu3.9) focal; urgency=medium
+
+  * d/p/0703-switch-on-unknown.patch
+    - Fix the headset-mic/headphone-mic selection on the machines without
+      internal mic, backported from:
+      https://gitlab.freedesktop.org/pulseaudio/pulseaudio/-/merge_requests/390
+      (LP: #1908167)
+
+ -- Hui Wang <hui.wang@canonical.com>  Tue, 15 Dec 2020 16:35:15 +0800
+
 pulseaudio (1:13.99.1-1ubuntu3.8) focal-security; urgency=medium
 
   * SECURITY UPDATE: don't rely on SCM_CREDENTIALS to detect snap confined
diff -Nru pulseaudio-13.99.1/debian/patches/0703-switch-on-unknown.patch pulseaudio-13.99.1/debian/patches/0703-switch-on-unknown.patch
--- pulseaudio-13.99.1/debian/patches/0703-switch-on-unknown.patch	1970-01-01 08:00:00.000000000 +0800
+++ pulseaudio-13.99.1/debian/patches/0703-switch-on-unknown.patch	2020-12-15 16:34:46.000000000 +0800
@@ -0,0 +1,24 @@
+Index: pulseaudio-13.99.1/src/modules/module-switch-on-port-available.c
+===================================================================
+--- pulseaudio-13.99.1.orig/src/modules/module-switch-on-port-available.c
++++ pulseaudio-13.99.1/src/modules/module-switch-on-port-available.c
+@@ -234,6 +234,11 @@ static void switch_to_port(pa_device_por
+     if (pp.is_port_active)
+         return; /* Already selected */
+ 
++    if (port->available == PA_AVAILABLE_UNKNOWN) {
++	if ((pp.sink && pp.sink->active_port && pp.sink->active_port->available != PA_AVAILABLE_UNKNOWN) ||
++	    (pp.source && pp.source->active_port && pp.source->active_port->available != PA_AVAILABLE_UNKNOWN))
++	    return;
++    }
+     pa_log_debug("Trying to switch to port %s", port->name);
+     if (!pp.is_preferred_profile_active) {
+         if (try_to_switch_profile(port) < 0) {
+@@ -304,6 +309,7 @@ static pa_hook_result_t port_available_h
+ 
+     switch (port->available) {
+     case PA_AVAILABLE_YES:
++    case PA_AVAILABLE_UNKNOWN:
+         switch_to_port(port);
+         break;
+     case PA_AVAILABLE_NO:
diff -Nru pulseaudio-13.99.1/debian/patches/series pulseaudio-13.99.1/debian/patches/series
--- pulseaudio-13.99.1/debian/patches/series	2020-10-16 05:23:13.000000000 +0800
+++ pulseaudio-13.99.1/debian/patches/series	2020-12-15 16:35:04.000000000 +0800
@@ -27,3 +27,5 @@
 0701-enable-snap-policy-module.patch
 0702-add-snappy-policy-module.patch
 
+0703-switch-on-unknown.patch
+