A clarinet riddle is:
 
Q: How do know a clarinet player is playing loud?
A: You can almost hear them.
 
The joke has been cited in print since at least 2007.
         
 
Klosi Jokes
Category: Music jokes
Date Added: 11/10/2007
Joke: Q: How do know a clarinet player is playing loud?A: You can almost hear them.
 
Twitter
Bollywood Sargam‏
@bollywoodsargam
Music jokes - 7668 Joke: Q: How do know a clarinet player is playing loud?
A: You can almost hear them. .... http://tinyurl.com/lh58v2
1:02 PM - 30 May 2009
     
Facebook
Clarinet Jokes
April 14, 2010 at 3:57pm
(...)
Q: How do know a clarinet player is playing loud?
A: You can almost hear them.
 
Google Books
Sensible Nonsense.. Frank’s Comic Pack:
Humour Pack Series
By Frank Paul
BookBaby
2014
Pg. ?:
Q: How do know a clarinet player is playing loud?A: You can almost hear them.
 
Twitter
Shit Band Kids Say‏
@Band__Member
How do you know when a clarinet is playing too loud? -You can almost hear them
12:37 PM - 23 May 2015
 
Twitter 
Lucky Score‏
@LuckyScoreNet
Q: How do know a
clarinet player is playing
loud?
A: You can almost hear them.
#Joke from #MusicJokes in #Jokes, #Humor and #Satire
8:25 AM - 17 Oct 2017