NY1 continues its celebration of Carnegie's Hall's 125th birthday with a look at how a hall built in 1891, before amplification and microphones, sounds so good. Stephanie Simon filed the following report.

Yo-Yo Ma with James Taylor, Itzhak Perlman with Renee Flemming, Isabel Leonard with Michael Feinstein - all thrilling musical combinations  But the star who has accompanied every great performer here is the sound.

Since its opening night, it's been said Carnegie Hall has perfect acoustics.

"What's astonishing is, you can hear a huge orchestra with a colossal amount of sound in there and it sounds perfect, but you can also hear just one instrument playing, and it's as if you're in the living room with them," said Clive Gillinson, executive and artistic director at Carnegie Hall.

Frequent performers agree.

"You know, the hall is like an instrument for me. For a musician, when you go into a hall that has good acoustics, it's like the hall allows you to play it," Perlman said.

"There are acousticians who work professionally now when a hall is designed to try and make it acoustically perfect, but with all the scientific data, they still can't assure 100 percent that a hall will have fantastic acoustics," Feinstein said.

"There's an incredible sound when it's just the orchestra and I get to sing with the orchestra with the acoustic sound, and it has its own beauty. And then all of a sudden, you get a mic, and it's also an incredible sound," Leonard said. "I don't know how the hall itself does it acoustically."

Actually, no one knows. Architect William Tuthill studied the great concert halls of Europe before designing Carnegie, but then went in a completely different direction.

"Firstly, it's 2,800 seats, which is huge for a concert hall. They’re normally 2,000 seats. Secondly, it's got curves front and back, which every acoustician will tell you is what you shouldn’t do. So somehow, he broke all the rules and got it better than anybody else has before or since," Gillinson said.

So how seriously do they take the sound here? Well, where else can you go where they give out cough drops? Just remember to unwrap yours before the concert begins.