How to enable a microphone for a USB headset?

From pactl-list

Card #0
    Name: alsa_card.pci-0000_00_1b.0
    Driver: module-alsa-card.c
    Owner Module: 23
    Properties:
        alsa.card = "0"
        alsa.card_name = "HDA Intel PCH"
        alsa.long_card_name = "HDA Intel PCH at 0xe1a60000 irq 32"
        alsa.driver_name = "snd_hda_intel"
        device.bus_path = "pci-0000:00:1b.0"
        sysfs.path = "/devices/pci0000:00/0000:00:1b.0/sound/card0"
        device.bus = "pci"
        device.vendor.id = "8086"
        device.vendor.name = "Intel Corporation"
        device.product.id = "1c20"
        device.product.name = "6 Series/C200 Series Chipset Family High Definition Audio Controller"
        device.form_factor = "internal"
        device.string = "0"
        device.description = "Built-in Audio"
        module-udev-detect.discovered = "1"
        device.icon_name = "audio-card-pci"
    Profiles:
        input:analog-stereo: Analog Stereo Input (sinks: 0, sources: 1, priority: 65, available: no)
        output:analog-stereo: Analog Stereo Output (sinks: 1, sources: 0, priority: 6500, available: yes)
        output:analog-stereo+input:analog-stereo: Analog Stereo Duplex (sinks: 1, sources: 1, priority: 6565, available: no)
        output:hdmi-stereo: Digital Stereo (HDMI) Output (sinks: 1, sources: 0, priority: 5900, available: no)
        output:hdmi-stereo+input:analog-stereo: Digital Stereo (HDMI) Output + Analog Stereo Input (sinks: 1, sources: 1, priority: 5965, available: no)
        output:hdmi-surround: Digital Surround 5.1 (HDMI) Output (sinks: 1, sources: 0, priority: 800, available: no)
        output:hdmi-surround+input:analog-stereo: Digital Surround 5.1 (HDMI) Output + Analog Stereo Input (sinks: 1, sources: 1, priority: 865, available: no)
        output:hdmi-surround71: Digital Surround 7.1 (HDMI) Output (sinks: 1, sources: 0, priority: 800, available: no)
        output:hdmi-surround71+input:analog-stereo: Digital Surround 7.1 (HDMI) Output + Analog Stereo Input (sinks: 1, sources: 1, priority: 865, available: no)
        off: Off (sinks: 0, sources: 0, priority: 0, available: yes)
    Active Profile: output:analog-stereo
    Ports:
        analog-input-front-mic: Front Microphone (type: Mic, priority: 8500, latency offset: 0 usec, not available)
            Properties:
                device.icon_name = "audio-input-microphone"
            Part of profile(s): input:analog-stereo, output:analog-stereo+input:analog-stereo, output:hdmi-stereo+input:analog-stereo, output:hdmi-surround+input:analog-stereo, output:hdmi-surround71+input:analog-stereo
        analog-input-rear-mic: Rear Microphone (type: Mic, priority: 8200, latency offset: 0 usec, not available)
            Properties:
                device.icon_name = "audio-input-microphone"
            Part of profile(s): input:analog-stereo, output:analog-stereo+input:analog-stereo, output:hdmi-stereo+input:analog-stereo, output:hdmi-surround+input:analog-stereo, output:hdmi-surround71+input:analog-stereo
        analog-output-lineout: Line Out (type: Line, priority: 9000, latency offset: 0 usec, not available)
            Part of profile(s): output:analog-stereo, output:analog-stereo+input:analog-stereo
        analog-output-speaker: Speakers (type: Speaker, priority: 10000, latency offset: 0 usec, availability unknown)
            Properties:
                device.icon_name = "audio-speakers"
            Part of profile(s): output:analog-stereo, output:analog-stereo+input:analog-stereo
        analog-output-headphones: Headphones (type: Headphones, priority: 9900, latency offset: 0 usec, not available)
            Properties:
                device.icon_name = "audio-headphones"
            Part of profile(s): output:analog-stereo, output:analog-stereo+input:analog-stereo
        hdmi-output-0: HDMI / DisplayPort (type: HDMI, priority: 5900, latency offset: 0 usec, not available)
            Properties:
                device.icon_name = "video-display"
            Part of profile(s): output:hdmi-stereo, output:hdmi-stereo+input:analog-stereo, output:hdmi-surround, output:hdmi-surround+input:analog-stereo, output:hdmi-surround71, output:hdmi-surround71+input:analog-stereo

However, after disabling the internal speaker through pactl unload-module 23 the microsoft teams app is giving a message that it was unable to detect a microphone.

The USB microphone from the headset is listed:

Having "removed" the internal speaker, sound was directed correctly to the headset -- but the mic isn't registering.

Prior to disabling the internal speaker, other voip apps were working fine. Now, along with microsoft teams, the textnow website doesn't seem to find a microphone.

The headset works fine on a different box, which is also running 21.04 but which lacks an internal speaker capable of playing music or other sounds through, I think, HDMI as the first box.

see also:

https://unix.stackexchange.com/a/263264/101935

blacklist snd-hda-intel

blacklist snd-hda-codec

thanks to damo22 on IRC.

I don't know why disabling the speaker by using pulseaudio would effect the microphone detection for the usb headset, but that would appear to the the situation.

I would still be curious as to how to do that either from alsa or from pulseaudio whilst leaving the drivers intact.