Just seconds after a concert begins, we know whether a performance will be exciting or not. Unfair as it seems, listeners respond intuitively to music long before the artful aspects of performance bring themselves to bear. Very often, that intuitive, emotional response is driven by the acoustical responsiveness of the concert hall. Even the world’s best artists or orchestras cannot overcome the deadening effect of a dull hall.

In music, as in life, first impressions rule. To a music lover, the first few seconds of a performance can conjure a blissful reaction or leave one cold. To most of us, appreciation of artistry or wonderment at virtuosity is not what we crave from music. Even those of us who might rank as connoisseurs are there to feel, not to think, and when we don’t experience what we hope for, we often leave blaming the artists or the art form when it is the hall that failed us.

Trust your own experience.
Have you even noticed while driving home that the music you hear from your car’s audio system sounds more exciting than the live concert you just left?
Such an experience might prompt you to think that you are no expert listener, but what you feel when you listen to music is genuine. You can distinguish when music sounds exciting to you and when it doesn’t, even though you cannot explain why. Take comfort in knowing that you are not alone.

The basics.
Among professionals, there is an understanding that while a musician plays an instrument, a concert artist plays a room. The room is the concert artist’s instrument. When a violin bow scrapes a string, causing it to vibrate, the string’s sound is colored and amplified by the violin which is, in turn, colored and delivered to the listener by the hall. Just as a factory-made violin is no match for a Stradivarius, some halls are no match when compared against others. The hall is that last critical link between the artist’s fingertips and your ears.
With concert hall acoustics, understanding your own emotional response can be traced back to distinct acoustical qualities of the room. The excitement, or lack thereof, can be traced back to the size, shape, and materials used to construct the room. Exciting concert halls are those which exhibit excellent running liveliness. Let’s explore the meaning of this concept – running liveliness – let’s start with the fundamentals.

Within a concert hall, the sound you hear results from of thousands of sound reflections bouncing off every surface within the room. Sound can reflect off dozens of surfaces, but those sound reflections which arrive first and loudest to your ears shape your emotional and physical response to the music.

It is not enough to hear a pin drop.
When the musician on-stage creates the music, the sound travels directly to your ears, but it also reflects from various surfaces all around you in the room: walls, ceiling, balcony fronts, pillars, etc. Sound reflects best off of hard, non-porous surfaces such as plaster and solid wood. Some surfaces, like people and fabrics, diminish or absorb sound reflections. Further, the angle and shape of a reflective surface determines whether sound is reflected to you in one bounce or many more. The proximity of the reflective surface to you determines just how quickly the reflected sound arrives to your ear. It also determines how loud that reflected sound will be when you hear it.

For you to hear subtlety and detail within music, you need strong and direct sound. You also need an abundance of loud sound reflections that arrive quickly – generally within 1/20th of a second. When the path of these sound reflections is sufficient, the concert hall exhibits clarity of sound. Clarity of sound (“you can hear a pin drop”) is important, but clarity, by itself, won’t excite you. The truth is that it is not enough to hear a pin drop. The sound has to be more than clear, it has to be beautiful.

What makes sound beautiful?
To most people, beautiful sound is reverberant. Reverberance is how long it takes sound to disappear after we first hear it. We call sound disappearance the “decay” of sound.
Reverberation time was a hot topic in the acoustics world. Most acousticians would agree that the ideal reverberation time ranges from 2 to 2.25 seconds for symphonic music. Think about this: You only hear the benefits of a 2+ second reverberation time when the music stops! So, reverberance heard when the music stops is desirable, but it is not what separates good concert halls from exciting concert halls.

So where does that excitement come from within great concert halls? It occurs when we can hear the reverberance of the concert hall as the music is ongoing!
For sound clarity, we need strong sound reflections arriving within 1/20th of a second following the creation of a music note while the music is ongoing. However, our ears are capable of gathering much more information from sound reflections that follow different paths within a concert hall from the stage to our ears. We also know that abundant sound is being held by the space because we can hear it linger when the music stops.
So, when the music is ongoing, what is the influence of sound we hear between the early sound reflections needed for clarity and those that we hear reverberate when the music stops?

Our Brain on Music:
Decades ago, audiology (the science of hearing) experts learned that, at every moment, our hearing system collects information for 1/4th to 1/3rd of a second before it becomes overloaded. Our hearing system collects and integrates the sound it hears over this significant fraction of a second, then we use everything we hear to form our overall impression of the sound. Long-lasting sounds are often very pleasing. For example, the sound of an ocean wave is more pleasing than the abrupt honk of a horn.
Our incredible hearing system is capable of collecting information about a musical note even when an additional two or more notes have already sounded. Our hearing system exhibits what could be called “running integration,” using all overlapping sounds to create our experience of the music. Hence, we can simultaneously hear and process the distinctive nature of a single note plus those abundant sound reflections that occur for the first 1/4th of second or longer. The potential for hearing and feeling the excitement within a great concert hall resides in each and every normal listener.

Running Liveliness
This is why some concert halls give us goosebumps and some don’t. Good concert halls offer clarity, but great concert halls allow you to hear the reverberance as the music is ongoing while preserving clarity. In the parlance of acoustics, halls which offer the ability to hear the liveliness of the hall as the music is ongoing exhibit excellent “running liveliness.”

How is running liveliness achieved within a concert hall? Those of us who design these halls must create a room of proper size, shape, and materials to provide both clarity and running liveliness. We must design the space so that a multiplicity of sound reflections arrive at your ears while ensuring that the sound reflections arriving 1/4th of a second or longer after the sound’s creation are strong and audible. When we’re successful, the music will be very exciting to you.