accent, distractions, fatigue, high speech rate, non standard phraseology, frequency changes, garbled messages, partial readbacks, etc
15
Mention some recommendations to improve ATC communication
keep instructions short, listen what a pilot reads back, speak slowly, break up the massages into short pauses, ask when your not sure about the information
20
Mention some causes of failure in verbal communication
uncommon language, failure to listen, technical factors, physiological reasons, failures to demonstrate understanding, etc