The businessman suggested his microphone may have been sabotaged
The US Commission on Presidential Debates has said there were "issues" with Donald Trump's audio during the first head-to-head debate.
Mr Trump and his Democratic rival Hillary Clinton battled it out for 90 minutes on Tuesday.
Speaking after the debate at Hofstra University, he had suggested his microphone may have been sabotaged.
"I had a problem with a microphone that didn't work - I don't know if you saw that in the room.
"But my microphone was terrible. I wonder if it was set up that way on purpose?
"My microphone, in the room they couldn't hear me, it was going on and off."
The US Commission on Presidential Debates has released this statement: "Regarding the first debate, there were issues regarding Donald Trump's audio that affected the sound level in the debate hall."
The Democratic and Republican candidates battled it out in front of an estimated television audience of 100 million.
It was often bad-tempered and prickly as the pair clashed over familiar ground from what has become the most expensive election campaign in history.
Mr Trump lambasted the political class, including Mrs Clinton, for allowing American jobs to leave the country.
The pair clashed over Mr Trump making money from the US mortgage crisis. "That's business," the billionaire said.
And he denied Hillary Clinton's accusation that he referred to climate change as a "hoax perpetrated by the Chinese" - something Mr Trump did tweet about back in 2012.
The role of the commission, established in 1987, is to ensure that the debates - as a permanent part of every general election - provide the best possible information to viewers and listeners.