現段階で元に戻した状態であり、下記の通りです。
$ head /proc/asound/card0/codec#0
Codec: Analog Devices AD1883
Address: 0
AFG Function Id: 0x1 (unsol 0)
Vendor Id: 0x11d41883
Subsystem Id: 0x10f70000
Revision Id: 0x100400
No Modem Function Group found
Default PCM:
    rates [0x7ff]: 8000 11025 16000 22050 32000 44100 48000 88200 96000 176400 192000
    bits [0xe]: 16 20 24

ちなみに、先日何故か音が一度音がなったのですが、マシンをリブートしたら、またならなくなりました。
イヤホンを接続して音を聞いていたあと、イヤホンを外してみたら、音がなりました。
今ではまたならない状態です。

pez562 による投稿:

$ head /proc/asound/card0/codec#0

これですと最初の10行しか表示されませんので、cat(1)を使って取得した結果を教えてください。

突然、音が鳴り始めました。
リブートすると、またならなくなる可能性があるので、
今のうちにcodec#0の内容を取得しておきます。（以下）

$ cat /proc/asound/card0/codec#0
Codec: Analog Devices AD1883
Address: 0
AFG Function Id: 0x1 (unsol 0)
Vendor Id: 0x11d41883
Subsystem Id: 0x10f70000
Revision Id: 0x100400
No Modem Function Group found
Default PCM:
    rates [0x7ff]: 8000 11025 16000 22050 32000 44100 48000 88200 96000 176400 192000
    bits [0xe]: 16 20 24
    formats [0x1]: PCM
Default Amp-In caps: ofs=0x00, nsteps=0x00, stepsize=0x00, mute=1
Default Amp-Out caps: ofs=0x27, nsteps=0x27, stepsize=0x05, mute=0
State of AFG node 0x01:
  Power states:  D0 D3
  Power: setting=D0, actual=D0
GPIO: io=3, o=0, i=0, unsolicited=1, wake=0
  IO[0]: enable=0, dir=0, wake=0, sticky=0, data=1, unsol=0
  IO[1]: enable=0, dir=0, wake=0, sticky=0, data=0, unsol=0
  IO[2]: enable=0, dir=0, wake=0, sticky=0, data=0, unsol=0
Node 0x02 [Audio Output] wcaps 0x30211: Stereo Digital
  Converter: stream=0, channel=0
  Digital:
  Digital category: 0x0
  IEC Coding Type: 0x0
  PCM:
    rates [0x7e0]: 44100 48000 88200 96000 176400 192000
    bits [0xe]: 16 20 24
    formats [0x5]: PCM AC3
  Delay: 3 samples
Node 0x03 [Audio Output] wcaps 0x405: Stereo Amp-Out
  Control: name="Headphone Playback Volume", index=0, device=0
    ControlAmp: chs=3, dir=Out, idx=0, ofs=0
  Device: name="AD1883 Analog", type="Audio", device=0
  Device: name="AD1883 Alt Analog", type="Audio", device=2
  Amp-Out caps: ofs=0x27, nsteps=0x27, stepsize=0x05, mute=0
  Amp-Out vals:  [0x22 0x22]
  Converter: stream=0, channel=0
  Power states:  D0 D3
  Power: setting=D0, actual=D0
Node 0x04 [Audio Output] wcaps 0x405: Stereo Amp-Out
  Control: name="Speaker Playback Volume", index=0, device=0
    ControlAmp: chs=3, dir=Out, idx=0, ofs=0
  Amp-Out caps: ofs=0x27, nsteps=0x27, stepsize=0x05, mute=0
  Amp-Out vals:  [0x22 0x22]
  Converter: stream=0, channel=0
  Power states:  D0 D3
  Power: setting=D0, actual=D0
Node 0x05 [Vendor Defined Widget] wcaps 0xf00000: Mono
Node 0x06 [Vendor Defined Widget] wcaps 0xf00000: Mono
Node 0x07 [Audio Mixer] wcaps 0x200103: Stereo Amp-In
  Amp-In caps: ofs=0x00, nsteps=0x00, stepsize=0x00, mute=1
  Amp-In vals:  [0x00 0x00] [0x80 0x80]
  Connection: 2
     0x22 0x21
Node 0x08 [Audio Input] wcaps 0x100501: Stereo
  Device: name="AD1883 Analog", type="Audio", device=0
  Converter: stream=0, channel=0
  SDI-Select: 0
  Power states:  D0 D3
  Power: setting=D0, actual=D0
  Connection: 1
     0x0c
Node 0x09 [Audio Input] wcaps 0x100501: Stereo
  Converter: stream=0, channel=0
  SDI-Select: 0
  Power states:  D0 D3
  Power: setting=D0, actual=D0
  Connection: 1
     0x0d
Node 0x0a [Audio Mixer] wcaps 0x200103: Stereo Amp-In
  Amp-In caps: ofs=0x00, nsteps=0x00, stepsize=0x00, mute=1
  Amp-In vals:  [0x00 0x00] [0x80 0x80]
  Connection: 2
     0x04 0x21
Node 0x0b [Audio Mixer] wcaps 0x200103: Stereo Amp-In
  Amp-In caps: ofs=0x00, nsteps=0x00, stepsize=0x00, mute=1
  Amp-In vals:  [0x80 0x80] [0x80 0x80]
  Connection: 2
     0x0f 0x21
Node 0x0c [Audio Selector] wcaps 0x30010d: Stereo Amp-Out
  Control: name="Capture Volume", index=0, device=0
    ControlAmp: chs=3, dir=Out, idx=0, ofs=0
  Control: name="Capture Switch", index=0, device=0
    ControlAmp: chs=3, dir=Out, idx=0, ofs=0
  Amp-Out caps: ofs=0x27, nsteps=0x36, stepsize=0x05, mute=1
  Amp-Out vals:  [0x2d 0x2d]
  Connection: 6
     0x14* 0x15 0x16 0x20 0x25 0x17
Node 0x0d [Audio Selector] wcaps 0x30010d: Stereo Amp-Out
  Amp-Out caps: ofs=0x27, nsteps=0x36, stepsize=0x05, mute=1
  Amp-Out vals:  [0xa7 0xa7]
  Connection: 6
     0x14* 0x15 0x16 0x20 0x25 0x17
Node 0x0e [Audio Selector] wcaps 0x300101: Stereo
  Connection: 2
     0x03* 0x04
Node 0x0f [Audio Selector] wcaps 0x300101: Stereo
  Connection: 2
     0x03* 0x04
Node 0x10 [Beep Generator Widget] wcaps 0x70000c: Mono Amp-Out
  Control: name="Beep Playback Volume", index=0, device=0
    ControlAmp: chs=1, dir=Out, idx=0, ofs=0
  Control: name="Beep Playback Switch", index=0, device=0
    ControlAmp: chs=1, dir=Out, idx=0, ofs=0
  Amp-Out caps: ofs=0x0f, nsteps=0x0f, stepsize=0x0b, mute=1
  Amp-Out vals:  [0x8f]
Node 0x11 [Pin Complex] wcaps 0x40018d: Stereo Amp-Out
  Control: name="Headphone Playback Switch", index=0, device=0
    ControlAmp: chs=3, dir=Out, idx=0, ofs=0
  Control: name="Front Headphone Jack", index=0, device=0
  Amp-Out caps: ofs=0x00, nsteps=0x00, stepsize=0x00, mute=1
  Amp-Out vals:  [0x00 0x00]
  Pincap 0x0000001f: OUT HP Detect Trigger ImpSense
  Pin Default 0x032140f0: [Jack] HP Out at Ext Left
    Conn = 1/8, Color = Green
    DefAssociation = 0xf, Sequence = 0x0
  Pin-ctls: 0xc0: OUT HP
  Unsolicited: tag=01, enabled=1
  Connection: 1
     0x07
Node 0x12 [Pin Complex] wcaps 0x40058d: Stereo Amp-Out
  Control: name="Speaker Playback Switch", index=0, device=0
    ControlAmp: chs=3, dir=Out, idx=0, ofs=0
  Control: name="Speaker Phantom Jack", index=0, device=0
  Amp-Out caps: ofs=0x00, nsteps=0x00, stepsize=0x00, mute=1
  Amp-Out vals:  [0x00 0x00]
  Pincap 0x0001001f: OUT HP EAPD Detect Trigger ImpSense
  EAPD 0x2: EAPD
  Pin Default 0x21214010: [Jack] HP Out at Sep Rear
    Conn = 1/8, Color = Green
    DefAssociation = 0x1, Sequence = 0x0
  Pin-ctls: 0x40: OUT
  Unsolicited: tag=00, enabled=0
  Power states:  D0 D3
  Power: setting=D0, actual=D0
  Connection: 1
     0x0a
Node 0x13 [Pin Complex] wcaps 0x40050c: Mono Amp-Out
  Amp-Out caps: ofs=0x1f, nsteps=0x1f, stepsize=0x05, mute=1
  Amp-Out vals:  [0x9f]
  Pincap 0x00010010: OUT EAPD
  EAPD 0x0:
  Pin Default 0x901701f0: [Fixed] Speaker at Int N/A
    Conn = Analog, Color = Unknown
    DefAssociation = 0xf, Sequence = 0x0
    Misc = NO_PRESENCE
  Pin-ctls: 0x40: OUT
  Power states:  D0 D3
  Power: setting=D0, actual=D0
  Connection: 1
     0x1f
Node 0x14 [Pin Complex] wcaps 0x40008b: Stereo Amp-In
  Control: name="Mic Boost Volume", index=0, device=0
    ControlAmp: chs=3, dir=In, idx=0, ofs=0
  Control: name="Mic Jack", index=0, device=0
  Amp-In caps: ofs=0x00, nsteps=0x03, stepsize=0x27, mute=0
  Amp-In vals:  [0x03 0x03]
  Pincap 0x00003727: IN Detect Trigger ImpSense
    Vref caps: HIZ 50 GRD 80 100
  Pin Default 0x03a190f0: [Jack] Mic at Ext Left
    Conn = 1/8, Color = Pink
    DefAssociation = 0xf, Sequence = 0x0
  Pin-ctls: 0x24: IN VREF_80
  Unsolicited: tag=02, enabled=1
Node 0x15 [Pin Complex] wcaps 0x40008b: Stereo Amp-In
  Amp-In caps: ofs=0x00, nsteps=0x03, stepsize=0x27, mute=0
  Amp-In vals:  [0x00 0x00]
  Pincap 0x00003727: IN Detect Trigger ImpSense
    Vref caps: HIZ 50 GRD 80 100
  Pin Default 0xb7a70121: [Fixed] Mic at Oth Mobile-In
    Conn = Analog, Color = Unknown
    DefAssociation = 0x2, Sequence = 0x1
    Misc = NO_PRESENCE
  Pin-ctls: 0x02: VREF_GRD
  Unsolicited: tag=00, enabled=0
Node 0x16 [Pin Complex] wcaps 0x40058d: Stereo Amp-Out
  Amp-Out caps: ofs=0x00, nsteps=0x00, stepsize=0x00, mute=1
  Amp-Out vals:  [0x80 0x80]
  Pincap 0x00010037: IN OUT EAPD Detect Trigger ImpSense
  EAPD 0x0:
  Pin Default 0x9933012e: [Fixed] CD at Int ATAPI
    Conn = ATAPI, Color = Unknown
    DefAssociation = 0x2, Sequence = 0xe
    Misc = NO_PRESENCE
  Pin-ctls: 0x00:
  Unsolicited: tag=00, enabled=0
  Power states:  D0 D3
  Power: setting=D0, actual=D0
  Connection: 1
     0x0b
Node 0x17 [Pin Complex] wcaps 0x40020b: Stereo Digital Amp-In
  Amp-In caps: ofs=0x00, nsteps=0x03, stepsize=0x17, mute=0
  Amp-In vals:  [0x00 0x00]
  Pincap 0x00000020: IN
  Pin Default 0x97a601f0: [Fixed] Mic at Int Riser
    Conn = Digital, Color = Unknown
    DefAssociation = 0xf, Sequence = 0x0
    Misc = NO_PRESENCE
  Pin-ctls: 0x00:
Node 0x18 [Vendor Defined Widget] wcaps 0xf00100: Mono
  Connection: 1
     0x06
Node 0x19 [Power Widget] wcaps 0x500500: Mono
  Power states:  D0 D3
  Power: setting=D0, actual=D0
  Connection: 2
     0x20 0x21
Node 0x1a [Pin Complex] wcaps 0x400000: Mono
  Pincap 0x00000020: IN
  Pin Default 0x90f301f0: [Fixed] Other at Int N/A
    Conn = ATAPI, Color = Unknown
    DefAssociation = 0xf, Sequence = 0x0
    Misc = NO_PRESENCE
  Pin-ctls: 0x20: IN
Node 0x1b [Pin Complex] wcaps 0x40038d: Stereo Digital Amp-Out
  Amp-Out caps: ofs=0x27, nsteps=0x27, stepsize=0x05, mute=1
  Amp-Out vals:  [0xa7 0xa7]
  Pincap 0x00000014: OUT Detect
  Pin Default 0x014510f0: [Jack] SPDIF Out at Ext Rear
    Conn = Optical, Color = Black
    DefAssociation = 0xf, Sequence = 0x0
  Pin-ctls: 0x00:
  Unsolicited: tag=00, enabled=0
  Connection: 1
     0x02
Node 0x1c [Pin Complex] wcaps 0x40018d: Stereo Amp-Out
  Amp-Out caps: ofs=0x00, nsteps=0x00, stepsize=0x00, mute=1
  Amp-Out vals:  [0x80 0x80]
  Pincap 0x00003737: IN OUT Detect Trigger ImpSense
    Vref caps: HIZ 50 GRD 80 100
  Pin Default 0x21a19020: [Jack] Mic at Sep Rear
    Conn = 1/8, Color = Pink
    DefAssociation = 0x2, Sequence = 0x0
  Pin-ctls: 0x00: VREF_HIZ
  Unsolicited: tag=00, enabled=0
  Connection: 1
     0x24
Node 0x1d [Vendor Defined Widget] wcaps 0xf00100: Mono
  Connection: 25
     0x07* 0x0a 0x0b 0x0c 0x0d 0x0e 0x0f 0x11 0x12 0x13 0x14 0x15 0x16 0x19 0x1a 0x1c 0x1e 0x1f 0x20 0x21 0x22 0x23 0x24 0x25 0x26
Node 0x1e [Audio Mixer] wcaps 0x200103: Stereo Amp-In
  Amp-In caps: ofs=0x00, nsteps=0x00, stepsize=0x00, mute=1
  Amp-In vals:  [0x80 0x80] [0x80 0x80]
  Connection: 2
     0x0e 0x21
Node 0x1f [Audio Mixer] wcaps 0x200100: Mono
  Connection: 1
     0x1e
Node 0x20 [Audio Mixer] wcaps 0x20010b: Stereo Amp-In
  Control: name="Mic Playback Volume", index=0, device=0
    ControlAmp: chs=3, dir=In, idx=0, ofs=0
  Control: name="Mic Playback Switch", index=0, device=0
    ControlAmp: chs=3, dir=In, idx=0, ofs=0
  Amp-In caps: ofs=0x17, nsteps=0x1f, stepsize=0x05, mute=1
  Amp-In vals:  [0x80 0x80] [0x80 0x80] [0x80 0x80] [0x80 0x80] [0x80 0x80] [0x80 0x80] [0x80 0x80]
  Connection: 7
     0x14 0x15 0x16 0x1a 0x25 0x03 0x04
Node 0x21 [Audio Selector] wcaps 0x30010d: Stereo Amp-Out
  Amp-Out caps: ofs=0x1f, nsteps=0x1f, stepsize=0x05, mute=1
  Amp-Out vals:  [0x1f 0x1f]
  Connection: 1
     0x20
Node 0x22 [Audio Selector] wcaps 0x300101: Stereo
  Connection: 2
     0x03* 0x04
Node 0x23 [Audio Selector] wcaps 0x300101: Stereo
  Connection: 2
     0x03* 0x04
Node 0x24 [Audio Mixer] wcaps 0x200103: Stereo Amp-In
  Amp-In caps: ofs=0x00, nsteps=0x00, stepsize=0x00, mute=1
  Amp-In vals:  [0x80 0x80] [0x80 0x80]
  Connection: 2
     0x23 0x21
Node 0x25 [Audio Selector] wcaps 0x30010d: Stereo Amp-Out
  Amp-Out caps: ofs=0x00, nsteps=0x03, stepsize=0x27, mute=0
  Amp-Out vals:  [0x00 0x00]
  Connection: 1
     0x1c
Node 0x26 [Vendor Defined Widget] wcaps 0xf00100: Mono
  Connection: 3
     0x14* 0x15 0x1c
Node 0x27 [Vendor Defined Widget] wcaps 0xf00301: Stereo Digital
  Connection: 2
     0x08* 0x09
Node 0x28 [Vendor Defined Widget] wcaps 0xf0030d: Stereo Digital Amp-Out
  Amp-Out caps: ofs=0x00, nsteps=0x00, stepsize=0x00, mute=1
  Amp-Out vals:  [0x80 0x80]
  Connection: 2
     0x08* 0x09
Node 0x29 [Vendor Defined Widget] wcaps 0xf0030d: Stereo Digital Amp-Out
  Amp-Out caps: ofs=0x00, nsteps=0x00, stepsize=0x00, mute=1
  Amp-Out vals:  [0x80 0x80]
  Connection: 2
     0x08* 0x09
Node 0x2a [Vendor Defined Widget] wcaps 0xf00301: Stereo Digital
  Connection: 2
     0x01* 0x27

Mocchiさん

間に合いました。以下の通りです。

$ amixer -c 0 contents
numid=16,iface=CARD,name='Front Headphone Jack'
  ; type=BOOLEAN,access=r-------,values=1
  : values=off
numid=15,iface=CARD,name='Mic Jack'
  ; type=BOOLEAN,access=r-------,values=1
  : values=off
numid=17,iface=CARD,name='Speaker Phantom Jack'
  ; type=BOOLEAN,access=r-------,values=1
  : values=on
numid=14,iface=MIXER,name='Master Playback Switch'
  ; type=BOOLEAN,access=rw------,values=1
  : values=on
numid=13,iface=MIXER,name='Master Playback Volume'
  ; type=INTEGER,access=rw---R--,values=1,min=0,max=39,step=0
  : values=34
  | dBscale-min=-58.50dB,step=1.50dB,mute=0
numid=2,iface=MIXER,name='Headphone Playback Switch'
  ; type=BOOLEAN,access=rw------,values=2
  : values=on,on
numid=1,iface=MIXER,name='Headphone Playback Volume'
  ; type=INTEGER,access=rw---R--,values=2,min=0,max=39,step=0
  : values=39,39
  | dBscale-min=-58.50dB,step=1.50dB,mute=0
numid=23,iface=MIXER,name='PCM Playback Volume'
  ; type=INTEGER,access=rw---RW-,values=2,min=0,max=255,step=0
  : values=254,254
  | dBscale-min=-51.00dB,step=0.20dB,mute=0
numid=12,iface=MIXER,name='Mic Boost Volume'
  ; type=INTEGER,access=rw---R--,values=2,min=0,max=3,step=0
  : values=3,3
  | dBscale-min=0.00dB,step=10.00dB,mute=0
numid=8,iface=MIXER,name='Mic Playback Switch'
  ; type=BOOLEAN,access=rw------,values=2
  : values=off,off
numid=7,iface=MIXER,name='Mic Playback Volume'
  ; type=INTEGER,access=rw---R--,values=2,min=0,max=31,step=0
  : values=0,0
  | dBscale-min=-34.50dB,step=1.50dB,mute=0
numid=11,iface=MIXER,name='Capture Switch'
  ; type=BOOLEAN,access=rw------,values=2
  : values=on,on
numid=10,iface=MIXER,name='Capture Volume'
  ; type=INTEGER,access=rw---R--,values=2,min=0,max=54,step=0
  : values=45,45
  | dBscale-min=-58.50dB,step=1.50dB,mute=0
numid=6,iface=MIXER,name='Loopback Mixing'
  ; type=ENUMERATED,access=rw------,values=1,items=2
  ; Item #0 'Disabled'
  ; Item #1 'Enabled'
  : values=0
numid=9,iface=MIXER,name='Auto-Mute Mode'
  ; type=ENUMERATED,access=rw------,values=1,items=2
  ; Item #0 'Disabled'
  ; Item #1 'Enabled'
  : values=1
numid=19,iface=MIXER,name='Beep Playback Switch'
  ; type=BOOLEAN,access=rw------,values=1
  : values=off
numid=18,iface=MIXER,name='Beep Playback Volume'
  ; type=INTEGER,access=rw---R--,values=1,min=0,max=15,step=0
  : values=15
  | dBscale-min=-45.00dB,step=3.00dB,mute=0
numid=5,iface=MIXER,name='Independent HP'
  ; type=ENUMERATED,access=rw------,values=1,items=2
  ; Item #0 'Disabled'
  ; Item #1 'Enabled'
  : values=0
numid=4,iface=MIXER,name='Speaker Playback Switch'
  ; type=BOOLEAN,access=rw------,values=2
  : values=on,on
numid=3,iface=MIXER,name='Speaker Playback Volume'
  ; type=INTEGER,access=rw---R--,values=2,min=0,max=39,step=0
  : values=39,39
  | dBscale-min=-58.50dB,step=1.50dB,mute=0
numid=21,iface=PCM,name='Capture Channel Map'
  ; type=INTEGER,access=r----R--,values=2,min=0,max=36,step=0
  : values=0,0
  |     | chmap-fixed=FL,FR

numid=20,iface=PCM,name='Playback Channel Map'
  ; type=INTEGER,access=r----R--,values=2,min=0,max=36,step=0
  : values=0,0
  |     | chmap-fixed=FL,FR

numid=22,iface=PCM,name='Playback Channel Map',device=2
  ; type=INTEGER,access=r----R--,values=2,min=0,max=36,step=0
  : values=0,0
  |     | chmap-fixed=FL,FR

Mocchiさん

いろいろ考えてみたのですが、特に心当たりはありません。（おそらく）
マシンは、まだ、シャットダウンしていないのですが、リブートした場合、また、
元の状態に戻り、音がならなくなることは考えられますか。

pez562 による投稿:

リブートした場合、また、元の状態に戻り、音がならなくなることは考えられますか。

可能性はあると思います。

試しに以下の試行を行い、Pin Default の値が変わるようなことがあるかどうか確認してみると、ハードウェアの癖を把握する一助になるでしょう。。
1. 今のcodec#0ノードの出力をファイルに保存する
2. マシンを再起動する。
3. codec#0ノードの出力を比較する

試行回数は多ければ多いほどよいかと思います。

お久しぶりです。14.04 LTS 32ビットです。

何をした時に音が鳴るのか規則性をみつけました。
おそらく「サスペンド」です。

普通にシャットダウンし、コンピュータを起動した場合は、音はなりませんが、
「サスペンド」したあとに、再度起動しますと、音がなります。

シャットダウン後、最初から起動した場合でも音がなるとうれしいのですが、
どなたかアドバイスをください。