Headphone Sound Output Gets Mixed with the Line-Out Output

Question

Problem Summary

When the line-out speaker is selected as the sound output, the sound is fine. Sound comes only from the speakers connected to the line-out port. However, when the headphone is selected as the output device, sound comes out both from the headphone and the speakers.

(EDIT 1) I tested in Windows 10 (using a live USB), and the problem does not occur there. So, this is definitely a software issue.

Details

My desktop computer has three sound output options:

• HDMI/Display port (not used)
• Headphone port at the front (headphone connected)
• Line-out port at the back (speakers connected)

When line-out is selected as the output device, the sound is heard only from the speakers connected to the line-out port. No problem there.

However, when headphone is selected as the output device, the sound is heard both from headphones and the speakers connected to the line out port.

This is really strange and beats the very purpose of the headphone, namely, privacy and not disturbing others.

Current Settings

My sound card as found is as follows.

sudo aplay -l

**** List of PLAYBACK Hardware Devices ****
card 0: PCH [HDA Intel PCH], device 0: ALC3234 Analog [ALC3234 Analog]

rest snipped

I even tried setting the sound volume of the line-out to zero in settings. This works for the line-out speakers. However, this does not seem to have any effect on the sound volume when the headphone is selected. The line-out speakers are equally loud, even with the sound volume set to zero.

I am not sure whether the output from alsamixer will be useful. But here it goes anyway.

EDIT 1

I booted the PC in Windows 10 using a live USB. And tested the sound outputs again. The problem does not occur there. So, this is definitely a software (some configuration file?) issue.

---

EDIT 2

Output from pacmd list-sinks (produced when the problem was happening)

1 sink(s) available.
  * index: 1
  name: <alsa_output.pci-0000_00_1f.3.analog-stereo>
  driver: <module-alsa-card.c>
  flags: HARDWARE HW_MUTE_CTRL HW_VOLUME_CTRL DECIBEL_VOLUME LATENCY DYNAMIC_LATENCY
  state: RUNNING
  suspend cause: (none)
  priority: 9039
  volume: front-left: 18352 /  28% / -33.17 dB,   front-right: 18352 /  28% / -33.17 dB
          balance 0.00
  base volume: 65536 / 100% / 0.00 dB
  volume steps: 65537
  muted: no
  current latency: 22.61 ms
  max request: 4 KiB
  max rewind: 4 KiB
  monitor source: 1
  sample spec: s16le 2ch 44100Hz
  channel map: front-left,front-right
               Stereo
  used by: 1
  linked by: 1
  configured latency: 23.22 ms; range is 0.50 .. 2000.00 ms
  card: 0 <alsa_card.pci-0000_00_1f.3>
  module: 23
  properties:
      alsa.resolution_bits = "16"
      device.api = "alsa"
      device.class = "sound"
      alsa.class = "generic"
      alsa.subclass = "generic-mix"
      alsa.name = "ALC3234 Analog"
      alsa.id = "ALC3234 Analog"
      alsa.subdevice = "0"
      alsa.subdevice_name = "subdevice #0"
      alsa.device = "0"
      alsa.card = "0"
      alsa.card_name = "HDA Intel PCH"
      alsa.long_card_name = "HDA Intel PCH at 0xf7040000 irq 129"
      alsa.driver_name = "snd_hda_intel"
      device.bus_path = "pci-0000:00:1f.3"
      sysfs.path = "/devices/pci0000:00/0000:00:1f.3/sound/card0"
      device.bus = "pci"
      device.vendor.id = "8086"
      device.vendor.name = "Intel Corporation"
      device.product.id = "a170"
      device.product.name = "100 Series/C230 Series Chipset Family HD Audio Controller"
      device.form_factor = "internal"
      device.string = "front:0"
      device.buffering.buffer_size = "352800"
      device.buffering.fragment_size = "176400"
      device.access_mode = "mmap+timer"
      device.profile.name = "analog-stereo"
      device.profile.description = "Analog Stereo"
      device.description = "Built-in Audio Analog Stereo"
      module-udev-detect.discovered = "1"
      device.icon_name = "audio-card-pci"
  ports:
      analog-output-lineout: Line Out (priority 9000, latency offset 0 usec, available: yes)
          properties:
  analog-output-speaker: Speakers (priority 10000, latency offset 0 usec, available: no)
      properties:
          device.icon_name = &quot;audio-speakers&quot;
  analog-output-headphones: Headphones (priority 9900, latency offset 0 usec, available: unknown)
      properties:
          device.icon_name = &quot;audio-headphones&quot;

active port: <analog-output-headphones>

---

EDIT 3

Output from pactl list sink-inputs (while playing through the speakers, non-problem scenario)

Sink Input #20
  Driver: protocol-native.c
  Owner Module: 10
  Client: 34
  Sink: 1
  Sample Specification: float32le 2ch 44100Hz
  Channel Map: front-left,front-right
  Format: pcm, format.sample_format = "\"float32le\""  format.rate = "44100"  format.channels = "2"  format.channel_map = "\"front-left,front-right\""
  Corked: no
  Mute: no
  Volume: front-left: 65536 / 100% / 0.00 dB,   front-right: 65536 / 100% / 0.00 dB
          balance 0.00
  Buffer Latency: 42811 usec
  Sink Latency: 23180 usec
  Resample method: copy
  Properties:
      application.icon_name = "google-chrome"
      media.name = "Playback"
      application.name = "Google Chrome"
      native-protocol.peer = "UNIX socket client"
      native-protocol.version = "34"
      application.process.id = "3091"
      application.process.user = "masroor"
      application.process.host = "masroor-OptiPlex-5040"
      application.process.binary = "chrome"
      application.language = "en_US.UTF-8"
      window.x11.display = ":0"
      application.process.machine_id = "749ee17244e440b5b766e258f177b412"
      module-stream-restore.id = "sink-input-by-application-name:Google Chrome"

---

Output from pactl list sink-inputs (while playing through the headphones, problem scenario, sound coming out both from the headphones and speakers, though supposed to be coming out only from the headphones)

Sink Input #20
  Driver: protocol-native.c
  Owner Module: 10
  Client: 34
  Sink: 1
  Sample Specification: float32le 2ch 44100Hz
  Channel Map: front-left,front-right
  Format: pcm, format.sample_format = "\"float32le\""  format.rate = "44100"  format.channels = "2"  format.channel_map = "\"front-left,front-right\""
  Corked: no
  Mute: no
  Volume: front-left: 65536 / 100% / 0.00 dB,   front-right: 65536 / 100% / 0.00 dB
          balance 0.00
  Buffer Latency: 45714 usec
  Sink Latency: 22927 usec
  Resample method: copy
  Properties:
      application.icon_name = "google-chrome"
      media.name = "Playback"
      application.name = "Google Chrome"
      native-protocol.peer = "UNIX socket client"
      native-protocol.version = "34"
      application.process.id = "3091"
      application.process.user = "masroor"
      application.process.host = "masroor-OptiPlex-5040"
      application.process.binary = "chrome"
      application.language = "en_US.UTF-8"
      window.x11.display = ":0"
      application.process.machine_id = "749ee17244e440b5b766e258f177b412"
      module-stream-restore.id = "sink-input-by-application-name:Google Chrome"

Answer 1

You could try enabling the feature of simultaneous output, check how it works, and then disabling it. Perhaps that fixes your problem.

Install paprefs, run it, and enable Simultaneous output. Then run pavucontrol and go to Output devices, and try tinkering with the options (you should see Simultaneous output...). Or go to Settings -> Sound -> Output -> Simultaneous output..., and also tinker with that.

In the meantime, you could check if you see anything strange in pavucontrol -> Configuration.

Sources:

1. Play sound through two or more outputs/devices