The announcer's voice sounds "hollow" when we use the TI-101 Telephone Interface.
Under normal conditions you will notice leakage of the host audio into the caller audio. This is the nature of analog hybrids. When properly adjusted, the caller’s audio level should be 3 to 6dB higher than the host audio leakage. Since this leakage is out of phase with the source audio a change in tonal quality is normal.