Polycom SIP 3.1 - Manual (Page 199)

Configuration Files
A - 45
Acoustic Echo Cancellation
These settings control the performance of the speakerphone acoustic echo
canceller.
.
voice.handset.txag.adjust.IP_650 18
voice.handset.sidetone.adjust.IP_330 3
voice.handset.sidetone.adjust.IP_430 3
voice.handset.sidetone.adjust.IP_650 0
voice.headset.rxag.adjust.IP_330 4
voice.headset.rxag.adjust.IP_430 1
voice.headset.rxag.adjust.IP_650 1
voice.headset.txag.adjust.IP_330 21
voice.headset.txag.adjust.IP_430 39
voice.headset.txag.adjust.IP_650 21
voice.headset.sidetone.adjust.IP_330 -3
voice.headset.sidetone.adjust.IP_430 -3
voice.headset.sidetone.adjust.IP_650 -3
Attribute Default
Polycom recommends that you do not change these values.
Attribute Default
voice.aec.hs.enable 1
voice.aec.hs.lowFreqCutOff 100
voice.aec.hs.highFreqCutOff 7000
voice.aec.hs.erlTab_0_300 -24
voice.aec.hs.erlTab_300_600 -24
voice.aec.hs.erlTab_600_1500 -24
voice.aec.hs.erlTab_1500_3500 -24
voice.aec.hs.erlTab_3500_7000 -24
voice.aec.hd.enable 0