This week I spent two days with Sound Designer Seb Frost as he supervised the fit-up for a musical. Planning and building the acoustics for a large auditorium is a delicate a and complicated business; a slight difference in the angle of how a speaker is hung can radically alter the sound-experience of the audience. As sound waves bounce around the wall and seats, weird things happen. Sound smears and distorts in the back seats, appears where you don’t expect it or gets lost altogether. Complicated looking computer programmes are used to work out exactly how high and at what angle each speaker needs to hang for the clearest sound across the whole area.
The human ear is a precise instrument. It picks up the direction from which a sound is coming by noticing millisecond differences in the acoustic field. This is ability is used to balance out sound in a performance by putting delays of fractions of seconds on the speakers. A person sitting at the top of the back row will still identify sound as coming from the stage even though they are really hearing through the speaker above their heads, because their ears will detect the source of the sound a split second before the speaker repeats it.
The sound designer’s job is intimately connected to audience experience, although invisible, It is akin to sculpture – manipulating and shifting the acoustic field to create a coherent shape, an audible body, an environment.