英文關鍵字
address
alert
amp
amplification
amplifier
announce
announcement
arena
audio
blue
broadcast
bunch
calling
communication
concert
cone
danger
electric
electronic
event
inform
information
loud
loudspeaker
mast
megaphone
music
new
old
outdoor
pole
post
power
public
rusty
shout
siren
sky
sound
speak
speaker
sports
system
talk
tree
voice
volume
warn
warning
wire
wiring