Bad audio on a new Asterisk machine

I have installed Asterisk 17.3 on a new machine of the same configuration as the previous one (4GB RAM, 1 core2Duo processor), but the sound (alaw codec) is not smooth, but randomly distorted (slightly stuttering). I the dialplan this is the Background and SayDigits applications.

How to adjust the quality of sound? I have tried both the new and traditional alaw algorithms.

(1)Did you check there’s no packet loss in your network?
(2)Is there any other process consuming most of the OS resources at the same time?

With the pjsip show channelstats command I did not see any packet loss on the leg of my call. The CPU load is 1-3 percent. I think the problem may lie in wrong configuration settings. Earlier I used to have such a problem more seriously, but I solved it with Wait command for 0,2 seconds. On the new machine the setting "transmit_silence_during_record " was set to no. I just turned it on, and audio became better, but the problem did not entirely disappear.

CPU load is not the only problem, if your load avg. is high, audio problems are common, even though CPU usage is only a few percent. Check the load with the uptime command, and make sure it’s no higher than the number of CPUs in the system. (That would be 2 in case of a dual core CPU)

RAM should be no problem, asterisk is not that memory hungry. (At least not in version 16 that I’m running)

It says load average: 0.01, 0.01, 0.00

Maybe it is due to pauses in audio (between words)? I have noticed that, if there is a pause at the beginning, my files stutter more often. If I remove them, they are played better. But occasionally they do not play well. This is annoying.

I would look at the media stream, with wireshark. Are there comfort noise frames, which Asterisk doesn’t handle? Is there excessive jitter?

I think this has something to do with comfort noise or silence. My audio files (IVR menus) have speech together with pauses. I have recently enabled Transmit silence during rec, it is better now. Any other settings, I may adjust? I will take a trace to check for comfort noise frames.

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