[pulseaudio-discuss] acceptable noise level for mic boost
linux at rempel-privat.de
Fri Nov 29 12:56:46 PST 2013
Am 29.11.2013 17:22, schrieb Tanu Kaskinen:
> On Fri, 2013-11-22 at 18:34 +0100, Oleksij Rempel wrote:
>> Am 22.11.2013 17:48, schrieb Tanu Kaskinen:
>>> On Thu, 2013-11-21 at 16:42 +0100, Oleksij Rempel wrote:
>>>> Hello all,
>>>> i posted this email to ALSA, but probably PA devs have some ideas too.
>>>> Hello Takashi,
>>>> what is acceptable noise level for mic boost?
>>>> My laptop has three levels of mic boost (+36dB). Level 3 is useless
>>>> since noise level will be about 0db. With level 1 i get -12dB noise, so
>>>> there is almost 12dB room for data... but it is not enough for normal
>>>> speech, which is about 20dB.
>>>> Are there any ALSA guide for HW designers, which will say some thing
>>>> like acceptable levels are 90-20dB?
>>>> There are some Skype and Microsoft prescriptions for certification.
>>>> For example M$ prescribe 18dB or more for speech to noise ration for
>>>> build in mics. It sound like good number to start.
>>>> In my case, i need to remove mic boost completely to guarantee minimum
>>>> 18dB SpNR. Suddenly i didn't found correct way to do it.
>>>> I will be thankful for some tip.
>>>> So my question to PA devs. Do pulse audio need to know about noise level
>>>> of microphone? Will it help to make correct decisions? Especial for VoIP
>>>> and automatic gain control.
>>> We don't currently have any idea of the noise level, so we don't have
>>> code for adjusting our decisions based on that information either. So,
>>> I'd say that pulseaudio doesn't *need* to know about the noise level. Of
>>> course, if someone someday complains that pulseaudio does bad decisions
>>> because it doesn't take the noise level into account, then we would need
>>> that information.
>> Thank you for your response.
>> I have more questions:
>> Skype continuously trying to adjust record level.
> I've never used Skype, but I think I've heard that it allows you to
> disable the automatic gain control. I'd expect that to help with your
Well, it is workaround but not fix. To make conference call we need
automatic gain control. Disabling it will work only for single person
call. The question is how to fix it?
I tested 7 different notebooks, and 4 of them had this issue. It is
nearly impossible for alsa to know about all of them.
I'll snip other part of discussion. Right now it is less important.
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