Ola @lmoraes.oliveira,
Eu encontrei isso neste link:
https://www.cisco.com/c/en/us/support/docs/voice/voice-quality/30141-symptoms.html#anc24
Synthetic Voice
Symptom - The term synthetic means that the sound of the voice is artificial and with a quiver or fuzz. Predictive insertion causes this synthetic sound by replacing the sound lost when a packet is dropped with a best guess from a previous sample. Synthetic and choppy voice commonly occur together.
Cause - A common cause is single packet loss or delay beyond the bounds of the dejitter buffer playout period. DSP predictive insertion causes the synthetic quality of the voice. For example, when a call is provided insufficient bandwidth (such as G711 codec across 64Kbps).
Espero que você ache útil.
Saudações
