You are using HLDS VoiceTranscoder plugin, which corrects the voice problems of non steam (old clients) and steam (new clients) players. Fix was made by Chuvi, great thanks to him :) Fix plugins requires Orpheu module to run. Fix works for build 6027 or higher
I recommend to disable plugin debug by vtc_hltv_debug.
Bug where on HLTV you can hear players voice who are connected before HLTV. Great thanks to Safety1st for troubleshooting and tests. Fix was made by me.
Also i see some scripters doesn't checks HLTV while working with voice chat in theirs amxx plugins. So disable all plugins related to voice chat and recheck hltv voice record.