Incorrect spelling, explanation: the combination of a letter a and a double c is very popular in English, for example, as it is in the word according. Probably because of that, a common mistake is to spell the word acoustic as accoustic, which is wrong. The only correct spelling is with a single c letter.

Correct spelling, explanation: an English word acoustic comes from akoustikos, which is a Greek word that used to mean of or for hearing. Later, the word appeared in Latin, and finally, in Middle Ages, it entered Middle English. However, it was not until the 18th century that the word acoustic started to be associated with the science of sound.

Definition of acoustic:
1. adjective – related to hearing or sound,
The acoustic qualities of this equipment are too poor for this price.
2. adjective – types of musical instruments,
Acoustic instruments are slowly becoming the things of the past.
3. noun – the sound qualities of a building,
The acoustic of the church is so amazing that you can hear somebody whispering in another corner.

Collocations with acoustic:
Some common collocations with acoustic include: acoustic wall, acoustic nerve, acoustic ceiling;
They built an acoustic wall in the theatre for better sound quality.
He used to be a DJ, but it damaged his acoustic nerve and he had to quit.
The acoustic ceiling absorbs the sound really well.