Wireless relay apparatus, first terminal apparatus, second terminal apparatus, communication system that performs communication of sound signals

A communication system comprising:

• a first terminal apparatus that transmits a first sound signal with an identifier attached thereto;
• a wireless relay apparatus that transmits the first sound signal as a second sound signal along with the identifier, when the first sound signal with the identifier attached thereto is received from the first terminal apparatus;
• and
• a second terminal apparatus that receives the second sound signal with the identifier attached thereto from the wireless relay apparatus,
• wherein the wireless relay apparatus includes:
• a recording hardware or hardware plus software that records the first sound signal and the identifier received;
• a sound quality evaluation hardware or hardware plus software that evaluates a quality of the first sound signal received, that transmits the identifier to the first terminal apparatus as a retransmission request identifier, when an evaluation value is lower than a threshold value, and that replaces the first sound signal recorded in the recording hardware or hardware plus software with the first sound signal re-received, when the first sound signal with the retransmission request identifier attached thereto is re-received from the first terminal apparatus and when the evaluation value is equal to or higher than the threshold value:
• and
• a relay recording control hardware or hardware plus software that, when the identifier received last in time by the second terminal apparatus is received from the second terminal apparatus as a last identifier, transmits a list of identifiers recorded in the recording hardware or hardware plus software after the last identifier to the second terminal apparatus, and that, when the identifier included in the list is received from the second terminal apparatus as a transmission request identifier, extracts the first sound signal corresponding to the transmission request identifier from the recording hardware or hardware plus software and transmit the first sound signal extracted to the second terminal apparatus as the second sound signal.