The screenshot-and-re-read card for location sound. Keep it on your phone; glance at it before any shoot with dialogue. The one idea under all of it: you can't fix location sound in post — you monitor it, protect it, and record room tone, every time.
The definitions, in one line each
Term
Definition
Double-system sound
Picture on the camera, audio on a separate device, married in the edit. (vs. single-system = both in the camera.)
Sync
Aligning separately-recorded audio to its picture so lips and sound match again.
Scratch / reference track
The camera's own (thin) mic, kept rolling for sync and backup — never used in the final mix.
Monitoring
Actively listening to the recorder's output on closed-back headphones while you record.
Levels
How loud the recorded signal is, read in dBFS (where 0 dBFS is the hard ceiling).
Headroom
The gap in dB between your loudest peaks and 0 dBFS — your safety margin.
Noise floor
The quietest sound a system records (its hiss); keep dialogue far above it.
Location sound
The craft of capturing usable audio in real, uncontrolled spaces — managing the world, not silencing it.
Wind protection
Shielding the mic from moving air (foam indoors, furry cover outdoors, your body, a sock).
Room tone
The unique ambient sound of a space with no one talking — recorded 30–60 s at every setup.
Double-system + sync — the ritual
Step
Do
Why
1
Roll camera and recorder
Two independent captures.
2
Keep the camera mic on (scratch)
Sync reference + backup.
3
Hold a hand/clapper in frame
The editor can see it.
4
Say the take number aloud
The audio labels itself.
5
Clap once, sharply
One spike in both files → stack the spikes to sync (Ch.27, §27.4).
Iron rule: never shoot double-system with no scratch track and no clap. 📱 Phone path: lav → second phone (clean) + camera/first phone (picture + scratch), clap once. Identical principle, zero cost.
Booming cheat sheet
Question
Answer
Default position?
Overhead, aimed down at the mouth (rejects floor/foot noise; natural voice).
When go below?
Only if forced: a wide shot, a low ceiling, or a boom shadow on a hard key.
Aim at?
The mouth (on-axis), not the chest or forehead.
How close?
As close as the frame allows — a hand's width out of frame. Closer beats louder room.
Grip?
Hands apart, arms up, elbows braced to the ribs, plant against a hip/wall. It's athletic.
Two people?
Favor the talker — swing to whoever speaks, lead the next line. Don't park dead-center.
Partner language
Camera op is the boom op's eyes: "you're clear / dipping / watch the shadow."
Boom shadow?
Work the subject's shadow side, keep the pole out of the key's throw, angle it, or soften the key.
Monitoring — what to listen FOR (the meter can't)
Fault
Sounds like
On-set fix
Clipping / distortion
crackle on loud words
lower gain; more headroom (§15.4)
Hum / buzz
steady electrical drone (50/60 Hz)
move cables, kill dimmers/appliances
HVAC / fridge / fans
low continuous whoosh/motor
turn it OFF (note to turn back on!)
Wind / rumble
low roar or thumps
wind protection + high-pass
Clothing rustle (lav)
scratchy friction on movement
re-mount away from moving/synthetic fabric
Plosives
"p"/"b" thumps
angle mic off-axis, add foam
Echo / room
hollow, distant, "bathroom"
get closer + deaden the room
Off-mic drift
level swims as they turn
re-aim; brief the subject
Intermittent hits
plane, truck, phone buzz
pause, re-take
Dropouts (wireless)
momentary silence/static
check batteries, range, interference
Rules: closed-back headphones only (wired > Bluetooth); monitor the recorder's output; do a listen-back before the real take; keep the cans on during every take.
Levels & headroom — the numbers
Target
Value
Note
Dialogue average
~-12 dBFS
above the noise floor, below the ceiling
Peak ceiling
under ~-6 dBFS
test the loudest line, not the average
Headroom to keep
6–12 dB
more for events (unrepeatable applause/laughter)
Ceiling
0 dBFS
a hard wall — clipping here is permanent
AGC (auto gain)
OFF
stops the noise floor "pumping" in pauses
Safety/backup track
ON, ~-12 dB lower
insurance for surprise clips / one-take moments
Bit depth
24-bit if available
forgiving of a conservative level
The safe direction is DOWN. A clean quiet take is a nudge in post; a clipped take is a re-shoot. Set-and-forget for interviews; ride the fader only for unpredictable events.
furry cover + your body between wind & mic; angle away
✗ — fix on set
Breath / plosives / indoor air
foam windscreen; angle mic off-axis
partly
Low rumble (traffic, HVAC vibration)
high-pass filter (~80 Hz); shock mount
partly
Handling noise
shock mount, cable slack, don't touch the mic
✗
Lav clothing rustle
re-mount under a stable collar, away from synthetics; cable loop
✗
Steady background hum/drone
kill the motor at the source; aim mic rejection at it
✓ if steady (Ch.33, §33.2)
Proximity is your #1 weapon: halving mic-to-mouth distance buries reverb and noise under the voice. You can't cleanly un-echo or un-wind a voice in post — so fix those on set.
Room tone — the non-negotiable 30–60 seconds
Question
Answer
When?
End of every setup, before you move/strike anything.
How?
Same mic, same position, same levels as the dialogue. Everyone holds still and silent.
How much?
30–60 seconds (60+ for events).
How many?
One per location and setup — a borrowed tone won't match.
What it does
Fills gaps · smooths cuts · patches deletions (a cough) · keeps sound continuous (Ch.9's continuity, for the ears).
Pays off in
The assembly (Ch.26, §26.6) and the ambience mix (Ch.33, §33.5).
Threshold idea:silence is never silent. Every room has a real, recordable sound — capture it deliberately or the edit will have a hole it can't fill.
When to use what — a quick decision aid
Situation
System
Mic
Levels
Extra
Controlled interview / talking-head
single or double
lav or boom, close
set-and-forget -12
tame the room; room tone
Two-person dialogue
double
boom (favor talker) or 2 lavs
set-and-forget
watch boom shadow; room tone
Noisy location (café, street)
double
close lav(s) + boom
conservative
aim rejection at noise; capture the ambience as tone
Event / one take
double + (board feed if available)
lav primary + shotgun safety
conservative -14, safety track ON
monitor throughout; note faults; room tone before the room clears
Outdoors / windy
double
shotgun + furry cover
conservative
body-block the wind; high-pass on
Top common mistakes → fixes
Mistake
Fix
Double-system with no scratch/clap
Leave the camera mic on; clap once, every take.
Watching the meter, not listening
Closed-back headphones on; listen for the 10 faults.
Taking the cans off once it "sounds fine"
Keep monitoring through every take — especially at events.
Recording "hot to be safe" (peaks at 0)
Aim -12, keep 6+ dB headroom; test the loudest line.
Leaving AGC on
Turn it off; set gain manually.
Fighting reverb with EQ in post
Get closer and deaden the room on set.
Leaving the HVAC/fridge running
Kill every motor before rolling (and turn it back on after!).
Skipping room tone
30–60 s at every setup — it can't be made later.
Booming dead-center in a 2-shot
Favor the talker; swing and lead the lines.
Lav on a stiff nylon jacket
Re-mount to calmer fabric; loop the cable.
Story & craft principles (Part III throughlines)
Principle
Here it means
Sound is half the picture
Give audio equal weight to light; audiences leave over bad sound first.
You shoot for the edit
The clap, the scratch, matched levels, and room tone are all gifts to the editor (you).
Fix it in pre / on set, not in post
Scout the room's sound, kill motors, get close — you can't un-clip, un-echo, or invent room tone later.
Motivate every choice
Mic type, placement, and how clean the sound needs to be are storytelling decisions (see Altman, CS-01).
Your project increment (Production Checkpoint — Project 1 LOCK)
Record your final Project 1 talking-head audio: mic close & off-frame, monitored on headphones, levels at ~-12 dBFS with headroom, room tamed, motors off.
Grab 30 seconds of room tone — same mic, position, levels.
Project 1 is now fully shot (concept Ch.1 → camera/exposure Ch.2–5 → framing/shots Ch.6–7 → light Ch.11–13 → audio Ch.14–15). You will assemble it in Chapter 26.
The one-sentence version
Record on a separate track and clap to sync; monitor on headphones for the faults a meter can't see; set levels around -12 dBFS with headroom so nothing clips; beat reverb and wind by getting close and shielding the mic on set (post can't); and never wrap without 30–60 seconds of room tone — do these every time and your video will sound as intentional as it looks.