[asterisk-users] scratchy sound

[Flavio Goncalves]

Hi Vieri,

The sound I hear does not seem caused by packet loss, jitter or latency,
this problems usually produces a robotic or synthetic voice. It seems
produced by some kind of bad contact (most probable). It is strange that you
are seeing it using hard phones, I could bet on the headphones. Check also
for electric interference, it is very common for line filters to break
(broken capacitor usually) causing this kind of interference. Try also a
different codec such as G.711 (improbable).

Flavio E. Goncalves
www.asteriskguide.com

2010/4/9 Vieri <rentorbuy at yahoo.com>

> Hi,
>
> I'm experiencing a few (but meaningful) cases of audio distortion (or bad
> quality). I can't say yet how often this happens.
>
> Please listen to the following sound file:
>
> http://213.96.91.201/temp/distorted_audio_1.wav
>
> This was recorded by Asterisk while the local SIP caller was dialing out a
> SIP trunk (so the problem is on my side, definitely, and it doesn't seem to
> be related to the bandwidth between my peer and the SIP provider). You can
> hear a scratchy sound during the whole fragment.
>
> I can't determine the possible cause of this kind of distortion. Maybe an
> expert ear can give me a clue. It shouldn't be the Asterisk server's CPU
> usage. Could it be a network issue between the Asterisk system and the SIP
> client? (it happens with SIP hardphones as well as softphones so I guess
> it's improbable it's the client software/firmware) Both softphones and
> hardphones use GSM and usually work fine (this kind of issue is not too
> frequent). The LAN isn't dedicated to voice but has QoS prioritizing VoIP.
>
> Could the cause of the distortion be network-related? And only on "my"
> side? Should I consider other causes?
>
> Thanks,
>
> Vieri
>
>
>
>
>
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