The shape of the stage enclosure has a big effect on sound.
David Egan, in his excellent text “Architectural Acoustics” shows this graphically.
There’s a few interesting things going on here.
One is that the stage enclosure effects how much sound from the source actually is directed to the audience.
You can see in the Egan figure how more and more energy is usefully directed as you move down the figure.
At the bottom, ceiling shape comes into play as a helpful contributor.
The other interesting thing to note is that audience surface “raking” or sloping is helpful both for sightlines and for “soundlines”. It’s easier for sound to reach those towards the back if they’re elevated in a sloping seating arrangement.
There’s a peculiar and harmful effect that occurs in a flat seating arrangement with the seats arranged in neat rows. I’ll write about that in separate topic.
This figure concentrates the benefit of a good stage enclosure on the audience.
But it should be noted that a good stage enclosure also benefits the players.
Great concert halls such as Boston Symphony Hall (shown) have stage enclosures that help musicians hear each other by encouraging reflections within the stage enclosure and the audience for reasons already explained.
Jordan Hall at the New England Conservatory of Music is right across the street from the famous Boston Symphony Hall.
Jordan Hall is my absolute favorite concert hall. It has a big roomy stage like BSH but a much smaller house. Unamplified music can blow the foam off a cup of beer in there (if they allowed beer).
Note the similar stage enclosure as BSH.
Proscenium stages designed for the dramatic arts are often problematic for live music.
Usually a “fly loft” is part of the stage enclosure. This area above the stage can easily be 60’ tall and is where scenery is flown in and out using a system of ropes and pulleys.
Unfortunately, fly lofts are where lots of useful sound goes to die. Usually there’s so much stuff up in the loft that absorbs sound that it never really comes back for the benefit of the musicians or audience.
One is shown as an example.
And the “wing space” – the area to either side of the stage where performers and technicians can work without being seen by the audience, also tends to be unuseful for sound.
So how does a musician apply this information in their daily life?
I have my own ideas about that but I’m going to pause and ask if you would like to answer that question.
Hi Ken,
First - thank you for all this great information and food for thought.
quote:Originally posted by Ken-at-Bose:
So how does a musician apply this information in their daily life?
I have my own ideas about that but I’m going to pause and ask if you would like to answer that question.
Applicability
In some field of endeavour long since forgotten, I use to use the term “prefield” as a verb to describe the activity of heading out to a site to scope out the situation. I can’t recall the context and oddly, I cannot find a reference to this activity on the web either.
Anyway, I rarely play a gig these days without visiting the venue first. If I can’t do that then I will try to scope things out by checking out pictures on the web and talking to whoever is responsible for the stage. People are generally glad to take the time to talk to me about this. I think they view it as a professional approach to performing in an unknown venue.
I have some ideas and preferences about how things should be, and I use this time either in person or on the phone to negotiate to get as close as I can to an ideal situation. I haven’t figured out how to incorporate all of your information above, but I will work it in somehow.
Ceilings / the air up there / Vertical Dispersion
As I look at the diagrams, I wonder about the applicability of the discussion about ceiling reflections. Would you comment on that in light of the vertical dispersion characteristics of the L1®?
Well this is just great Ken, now I have to trailer a set of bleachers to every gig, except the ones at BSH and the like.
And for the Fly Loft, I’m going to have to bring a huge lighting truss the length and width of the stage with a solid top.
Jordan Hall is on my todo list, beautiful!
A few thoughts on how performers can use an understanding of ‘beneficial stage shapes’ to help themselves:
1) Educate the venue. Particularly if there is an opportunity for ST’s ‘prefield’ activity, you might be able to have the venue management add some acoustically reflective side walls.
2) Consider acoustics in your stage setup. For example, if you want to have a place to hide your cases and clutter, perhaps having some acoustically-reflective ‘stage framing’ can help with making any ‘wing space’ from being too much of problem.
3) Positioning of the L1 column. When you recognize that a stage has a ‘loft’ or there are ‘wings’ which might trap the sound – keep the L1 as far in front of them as feasible.
Remember the rule of thumb that every listener needs to be able to see all the L1 columns in order to hear them well – pay particular attention to the listeners on the sides.
4) Tilt the L1 column. If you can’t change the seating, change the angle and height of the L1 column so that it:
- is visible (top to bottom) by as much of the audience as possible.
- aims the ‘pancake of sound’ toward the center or center-back of the audience … without ‘skipping over’ the front rows.
While it doesn’t take much of a ‘tilt’ to eliminate annoying ‘slap-back’ echoes (an inch often suffices), it might take considerably more tilt to “cover” the varying heights of the listeners.