C. Crane BC75XLT - Manual (Page 3)

3
Set the volume to a comfortable audio level coming from
the speaker before plugging in the monaural earphone or
headset. Otherwise, you might experience some discomfort
or possible hearing damage if the volume suddenly becomes
too loud because of the volume control or squelch control
setting. This might be particularly true of the type of
earphone that is placed in the ear canal.