Is it possible to reduce voice delay transmission? Now it is about one second.
One second looks too much.
Run TestScene project from PhotonVoice package and look at RTT value shown in status line of PhotonVoice client. Value ~100 ms and below is ok and results in acceptable delays with default settings. Higher value means that ping to Photon server is too high. RTT is time required for packet to go to server and back. It equals about 2 ping times from your client to Photon server.
Also make sure that PhotonVoiceSettings "Play Delay Ms" parameter is not set accidentally to too high value (default is 200).