[Android Q&A, Help & Troubleshooting] Lusty Rugnuts:
I'm recording this here so I can revert the settings if I break something:

In /system/vendor/etc/audio_em.xml

The original settings:

<?xml version="1.0" encoding="utf-8"?>
<AudioParameter>
<DumpOptions>
<Category title="Output">
<Option type="SetAudioCommand" cmd="0x63" check="1" uncheck="0">Stream Output Dump</Option>
<Option type="SetAudioCommand" cmd="0x69" check="1" uncheck="0">A2DP Stream Output Dump</Option>
</Category>
<Category title="Input">
<Option type="SetAudioCommand" cmd="0x6B" check="1" uncheck="0">Stream Input Dump</Option>
</Category>
<Category title="USB">
<Option type="SetAudioCommand" cmd="0" check="1" uncheck="0">USB Output Dump</Option>
<Option type="SetAudioCommand" cmd="0" check="1" uncheck="0">USB Input Dump</Option>
</Category>
<Category title="AudioMixer">
<Option type="SetParameters" cmd="af.track.pcm" check="1" uncheck="0">AudioTrack Buffer Dump</Option>
<Option type="SetParameters" cmd="af.mixer.pcm" check="1" uncheck="0">AudioMixer Buffer Dump</Option>
<Option type="SetParameters" cmd="af.mixer.drc.pcm" check="1" uncheck="0">AudioMixer DRC Dump</Option>
<Option type="SetParameters" cmd="af.timestretch.in.pcm" check="1" uncheck="0">AudioMixer Timestretch Dump</Option>
<Option type="SetParameters" cmd="af.offload.write.raw" check="1" uncheck="0">AudioMixer Offload Dump</Option>
<Option type="SetParameters" cmd="af.mixer.dwnmx.pcm" check="1" uncheck="0">AudioMixer Surround Dump</Option>
<Option type="SetParameters" cmd="af.resampler.pcm" check="1" uncheck="0">AudioMixer SRC Dump</Option>
<Option type="SetParameters" cmd="af.mixer.end.pcm" check="1" uncheck="0">AudioMixer End Dump</Option>
<Option type="SetParameters" cmd="af.record.dump.pcm" check="1" uncheck="0">AudioMixer Record Dump</Option>
<Option type="SetParameters" cmd="af.mixer.limin.pcm" check="1" uncheck="0">AudioMixer Limiter Dump</Option>
</Category>
</DumpOptions>

<SetAudioCommand>
<Option>0x99, 1</Option>
<Option>0x98, 1</Option>
</SetAudioCommand>

<GetAudioCommand>
<Option>0x64</Option>
<Option>0x66</Option>
<Option>0x68</Option>
</GetAudioCommand>

<SetParameters>
<Option>TDM_Record=0</Option>
<Option>SET_MODE=0</Option>
<Option>HAHA=0</Option>
<Option>Set_SpeechCall_DL_Mute=0</Option>
<Option>SetFmVolume=0</Option>
<Option>ANC_CMD=0</Option>
<Option>af.dumplog=1</Option>
</SetParameters>

<GetParameters>
<Option>GetFmEnable</Option>
<Option>GetFmTxEnable</Option>
<Option>DUAL_MIC_GET_GAIN</Option>
</GetParameters>
</AudioParameter>

Time to test.

I tried the following (bolded) changes... they had no effect upon the logspam.

<?xml version="1.0" encoding="utf-8"?>
<AudioParameter>
<DumpOptions>
<Category title="Output">
<Option type="SetAudioCommand" cmd="0x63" check="1" uncheck="0">Stream Output Dump</Option>
<Option type="SetAudioCommand" cmd="0x69" check="1" uncheck="0">A2DP Stream Output Dump</Option>
</Category>
<Category title="Input">
<Option type="SetAudioCommand" cmd="0x6B" check="1" uncheck="0">Stream Input Dump</Option>
</Category>
<Category title="USB">
<Option type="SetAudioCommand" cmd="0" check="1" uncheck="0">USB Output Dump</Option>
<Option type="SetAudioCommand" cmd="0" check="1" uncheck="0">USB Input Dump</Option>
</Category>
<Category title="AudioMixer">
<Option type="SetParameters" cmd="af.track.pcm" check="1" uncheck="0">AudioTrack Buffer Dump</Option>
<Option type="SetParameters" cmd="af.mixer.pcm" check="1" uncheck="0">AudioMixer Buffer Dump</Option>
<Option type="SetParameters" cmd="af.mixer.drc.pcm" check="1" uncheck="0">AudioMixer DRC Dump</Option>
<Option type="SetParameters" cmd="af.timestretch.in.pcm" check="1" uncheck="0">AudioMixer Timestretch Dump</Option>
<Option type="SetParameters" cmd="af.offload.write.raw" check="1" uncheck="0">AudioMixer Offload Dump</Option>
<Option type="SetParameters" cmd="af.mixer.dwnmx.pcm" check="1" uncheck="0">AudioMixer Surround Dump</Option>
<Option type="SetParameters" cmd="af.resampler.pcm" check="1" uncheck="0">AudioMixer SRC Dump</Option>
<Option type="SetParameters" cmd="af.mixer.end.pcm" check="1" uncheck="0">AudioMixer End Dump</Option>
<Option type="SetParameters" cmd="af.record.dump.pcm" check="1" uncheck="0">AudioMixer Record Dump</Option>
<Option type="SetParameters" cmd="af.mixer.limin.pcm" check="1" uncheck="0">AudioMixer Limiter Dump</Option>
</Category>
</DumpOptions>

<SetAudioCommand>
<Option>0x99, 1</Option>
<Option>0x98, 1</Option>
</SetAudioCommand>

<GetAudioCommand>
<Option>0x64</Option>
<Option>0x66</Option>
<Option>0x68</Option>
</GetAudioCommand>

<SetParameters>
<Option>TDM_Record=0</Option>
<Option>SET_MODE=0</Option>
<Option>HAHA=0</Option>
<Option>Set_SpeechCall_DL_Mute=0</Option>
<Option>SetFmVolume=0</Option>
<Option>ANC_CMD=0</Option>
[B] <Option>af.track.pcm=0</Option>
<Option>af.mixer.pcm=0</Option>
<Option>af.mixer.drc.pcm=0</Option>
<Option>af.timestretch.in.pcm=0</Option>
<Option>af.offload.write.raw=0</Option>
<Option>af.mixer.dwnmx.pcm=0</Option>
<Option>af.resampler.pcm=0</Option>
<Option>af.mixer.end.pcm=0</Option>
<Option>af.record.dump.pcm=0</Option>
<Option>af.mixer.limin.pcm=0</Option>
<Option>af.dumplog=0</Option>[/B]
</SetParameters>

<GetParameters>
<Option>GetFmEnable</Option>
<Option>GetFmTxEnable</Option>
<Option>DUAL_MIC_GET_GAIN</Option>
</GetParameters>
</AudioParameter>