adult
alert
amplifier
announce
attention
background
black
blackboard
bullhorn
call
chalkboard
classroom
communication
copy
device
equipment
hand
holding
horn
information
learning
loud
loudspeaker
male
man
megaphone
news
noise
person
portable
power
proclaim
promotion
public
retro
school
shout
space
speak
speaker
student
study
text
university
vintage
voice
warning
young