Why Does Every Venue Sound Different, and What Can You Change?

Almost every crew that comes to us asks some version of the same thing: the venue sounded fine when we walked in, so why does the recording sound so poor? The short answer is that our ears filter a room very well, and a microphone does not. We stop hearing the air handling, the fridge in the corner, the traffic on the street outside. The recorder keeps all of it and often makes it louder, because we place the microphone to catch the voice and the room comes along with it.

This article belongs to the part of the course that deals with spotting and reducing echo, hum and background noise before recording starts. The aim is not a perfect room. Most interviews, panels and small events happen in spaces nobody chose for their acoustics. The aim is to know what you are listening for, find the worst problems early and make a handful of changes that cost little and take a few minutes.

Before any cable comes out of a case, stand where the speakers will sit and stay quiet for a full minute. Close your eyes if it helps. You are listening for sounds that run continuously, because those are the ones that cannot be edited out later. A low drone usually points to ventilation or a transformer. A thin buzz can come from lighting. A distant rumble may be a lift shaft or a road.

Then clap once, sharply, and listen to how long the sound lingers. A short, dull clap means the room is forgiving. A ring that hangs for a second or more tells you that bare walls, glass or a high ceiling will smear every word. Walk the space while you do this. Corners, the middle of a long wall and the area under a skylight can each sound quite different, and you may find a better seat for the speaker within a few steps.

• Stand still for a full minute and note every continuous sound
• Clap once and judge how long the ring lasts
• Test two or three positions rather than the first one offered

Echo is the complaint we hear about most, and it is also the one people try to fix in the wrong way. Hanging a single thin sheet on one wall rarely changes much. What works is putting soft, heavy or irregular material close to the speaker and close to the microphone: a sofa behind the guest, a coat rack full of coats, curtains drawn across a window, a rug laid over a hard floor.

Distance matters more than treatment. A microphone placed close to the mouth hears the voice far louder than the reflections, so the room matters less. That is why a lavalier clipped to a collar often beats a distant microphone in a hall, even a good one. If you must use a microphone further away, turn the speaker away from the largest reflective surface, and ask them to sit rather than stand, since a seated voice hits fewer hard walls on its way back to you.

• Put soft material behind and beside the speaker, not far across the room
• Bring the microphone closer instead of fighting the whole space
• Cover glass and bare floor where the speaker faces

Some noise has a source you can reach. Fridges, vending machines, projector fans and humming display screens can often be switched off or unplugged for the length of a session, provided you ask first and plug them back in afterwards. Doors and windows are the next easy gain. Closing a door to a corridor and a window to a busy street can lower the background more than any equipment you carry.

Mains hum is different. It tends to come from cables running alongside power leads or from dimmer-controlled lighting. Keep your audio cables apart from power cables, cross them at right angles if they must meet, and listen on headphones as you move them. If the hum changes when you shift a cable, you have found a cause. If a light dimmer is the source, ask for the lights to be set at full or switched to a different group for the shoot.

• Ask permission before switching off appliances, and note what you turned off
• Separate audio cables from power cables
• Check headphones while moving cables to find hum

Even after your changes, every room keeps a sound of its own. Capture it. Thirty seconds of silence with everyone still, recorded at the same levels as the session, gives an editor something to patch gaps with and a clean reference when they clean up a track. Do it once at the start, and again if something in the room changes, such as a heating system switching on in the afternoon.

Then make an honest call about what you are willing to live with. A faint, steady background can be tolerated; an intermittent noise cannot, because it will clash with speech again and again. If a venue will not let you fix the worst problem, say so before the session, not after. Producers appreciate hearing early that a space needs a second microphone, a closer position or a different seat, and it costs far less than a reshoot.

Autumn venues bring their own habits. Heating comes on, windows get closed against the cold and the air handling that was idle all summer starts to hum. Rooms that sounded dry in warm weather can turn noticeably different once the doors stay shut and the heating cycles on and off through a session.

A routine helps more than any one piece of kit. Arrive early, listen, clap, walk the room, silence what you can, place soft material, position the microphone close, record room tone and check on headphones before anyone sits down. It takes about ten minutes once you have done it a few times. Learners practise it in different spaces during the course, and by the end they run it without thinking about it.

• Arrive early enough to hear the room before the crew fills it
• Check the heating and air handling state, not just the quiet moment
• Run the same short routine at every venue