Question: My book is in first person but I was wondering if I could use words like Bam, Bang, or Boom like if the sentence was something like "I was running then bang the gun went off" or "It was quiet then boom we heard an explosion." So is it ok to use words like that or should I not use those kinds of words?Answer:
In first person, you write like the main character thinks. That's how you convey his/her unique personality to the reader.
Of course, your main character needs to be a great storyteller, but he/she must also be true to themselves. So it is fine to use a vocabulary that fits the character and to describe things the way the character would perceive them.
A unique voice is one of the key things agents and editors look for in a manuscript.
For example, an engineer might use a different vocabulary to describe an event than a doctor, and he will pick up on different details as well. Stories told from the point of view of someone who is intellectually challenged (e.g. Flowers for Algernon
or Forest Gump
) will use a different vocabulary than something written from the point of view of a scholar or a smart teenager.
In the examples you give, I might consider using all caps for BANG and BOOM to convey the impact of the sounds. I might also divide the sentences into two, putting a period before "Then," but that too is a choice that may or may not fit your character.