B747 First Officer reported an intercom failure to alert crew to EICAS messages resulted in rejected takeoff. First Officer reported AC BUS 1 failure led to multiple failures.

Narrative

On takeoff roll; accelerating through ~110 kts multiple amber messages began to appear on upper EICAS. Sitting in center observer's seat; I attempted to say 'EICAS' to alert flying crew to EICAS as there hadn't yet been an aural alert. At this time I realized my intercom was not functioning; so I leaned forward and simply pointed at it. Around the same time either Pilot Flying (PF) or Pilot Monitoring (PM) (I do not recall) called for the reject and the reject was performed. I looked down to see my audio control panel was dark; as well as a number of other lower pedestal panels. Although the thrust reversers all failed to deploy; the aircraft was able to decelerate and exit the runway at which point we began to taxi back to the gate. Some of the faults cleared on the way back; and my audio panel came back to life; however multiple status messages remained. The predominant caution was determined to be AC BUS 1; for which the PM ran the non-normal checklist. We parked without any significant further incident.Cause - Immediately after the reject we surmised that something had faulted with AC BUS 1; causing multiple issues; which filled more than one page of the EICAS. Among the remaining status messages after blocking back in; was all 4 reversers and Electronic Engine Controls (EEC).Suggestions - Nothing major at this time. High speed reject was performed to standard and with good crew-coordination despite partial loss of intercom; with minimal disruption to ZZZZ operations and without brake overheating.