Why does music sound different in different parts of a concert hall?

Mary Kay S. asks, "Dr. Volt, why is the sound different in different parts of a concert hall? Where should I sit to get the best sound?"

Ah, it all has to do with acoustics - the physics of how sound, well, sounds in a particular space. Every surface, be it the walls, the seats, and even the audience, will absorb or reflect the sound in a particular way. Concert halls are designed in order to maximize the quality of the sound, both for the listeners, but for the performers as well. If, for example, all the sound is absorbed by the walls, the ceiling, etc. before it ever has a chance to reach the audience's ears, then you can bet they will soon be making a very lively march towards the box office for a refund! The key is to create surfaces in the hall such that the sound is evenly distributed over the entire hall, but yet doesn't reverberate too long (else it will interfere with the sound still to come). It is also important that enough sound bounce back to the performers, so that they are able to hear one another. Otherwise while the audience may hear very clearly, the performance may not turn out to be worth hearing! As you can imagine this all poses a very difficult puzzle for the acoustical engineers designing the hall, further complicated by the fact that you have to take into account how the hall will sound when people are filling all of the seats.

The ancient Greeks were geniuses when it came to acoustics. Their amphitheatres were designed such that an actor on stage could be heard clearly by thousands of spectators all at once, a feat which proves a challenge even for our modern engineering.

As for the best place to sit, that I think is left in "the eye of the beholder." A well-designed concert hall should have excellent sound wherever you sit, and thus it all comes down to your own personal preference.

The Greek ampitheatre at Epidaurus