OK, I thought about it.
All is well except the calibration method.
I think there is a better way to accomplish more.
Calibration of systems is a pain.
So I looked for a constant volume sound source so that calibration
can be done in post where it belongs for a number of reasons.
To start with the starting environment and second the directional
values of different mics.
How about you find a 10 cent whistle with a ball in it. Buy 250 of
them and sell them with the program concept. Those whistles do not
change volume much with the amount you blow. It is broad freq so you
can see the mic response and if blown either before or after the
start of a track from 20 feet can be used to id the front to side
charecter of the mics as well as the freq response of those mics. It
can also then see how much of a reverberent site you are in. Then
calibration can remain in post where it belongs. I envision it being
blown at 20 feet at front and then side of the mics.
Rich
--- In Dan Dugan <> wrote:
> Dear friends, this is what we're doing in Muir Woods. Your comments
> will be appreciated.
>
> -Dan Dugan
>
> Recording Protocol for Soundscape Monitoring
> Version 2.0 (Draft)
>
> This is an attempt to set standards for audio recording in
> conjunction with attended soundscape monitoring, so that the work
of
> different recordists will be comparable.
>
> Format
> Stereo digital audio.
>
> Microphones
> Type: condensor.
> Frequency response: at least 40Hz to 16KHz
> Equivalent noise: lower than 25 dBA (signal to noise 69 dB or
better).
> Effective windscreens are essential. Manufacturer-provided
> foam windscreens are inadequate for outdoor work. Good windscreens
> can be home-made.
> Shockmounts are highly desirable, especially if hand-held.
>
> Stereo Microphone Arrays (listed in the order of preference, best
first)
> A: Spaced omnidirectional mics with barrier: Jecklin disc,
> shoulder mounts, head-worn quasi-binaural, lavs tied around a tree.
> B: ORTF array (cardioids spaced 17cm, splayed at 110 degrees).
> C: One-point stereo mic X-Y or M-S.
> Highly directional types like shotgun or parabolic dish are
> not applicable for soundscape recording.
>
> Recorders
> Any digital audio recorder with adequately quiet mic preamps.
> MiniDisc, Compact Flash or hard drive are all good. A record level
> control with steps is a plus. Some kind of scale on the record gain
> control (at least 0-10) is necessary for repeatability.
>
> Recording Level
> To establish a starting point, hold the microphone at arms
> length, sensitive side facing you. Speak normally to a person near
> you. Set the recording gain so that the peaks don't exceed a level
of
> -5dB on the recorder's meter. This gain will work for quiet
> environments. Loud sounds will require lower gains.
>
> Calibration
> An affordable scheme for calibrating field recording outfits
> is being sought. Here is one proposal:
> Terminology: "Recording Gain" is the setting of the recorder.
> "Recording Level" is the reading of the recorder's peak meter.
> Equipment: A digital audio workstation with speakers, a sound
> level meter, the recording outfit to be calibrated.
> Procedure:
> 1) Prepare a stereo track of pink noise. Make the channels
> uncorrelated if possible.
> 2) Filter the track with a high-pass at 200Hz and a low-pass at
2000Hz.
> 3) Play the track and read the sound level meter while adjusting
the
> monitor level to 65dBA (slow) at a normal listening position
> (measuring position).
> 4) Place your mic precisely at the measuring position and adjust
the
> recording gain so that the recorder's peak meter reads -5dB (this
is
> dBFS, meaning "decibels full-scale").
> 5) Note your recorder's gain setting. Use this as a standard gain
for
> recording in quiet places.
> 6) Make a one-minute recording of this calibration noise. Save it
to
> calibrate transfers later.
>
> Slates
> Each take should have a voice announcement (slate) at the
> head or tail including:
> Recordist's name
> Date
> Time
> Location
> Weather and wind conditions
> Microphone(s) model number
> Recorder model number
> Recorder gain setting
> Optional description of the scene and the
> sound sources you can identify, observed wildlife behavior.
>
> Monitoring
> Recording should always be monitored on headphones except
> when doing simultaneous attended logging. Attended logging must be
> done with naked ears.
>
> Delivery
> Make a CD with a track for each monitoring location. Five
> fifteen-minute locations with one-minute slates will just fit on an
> 80-minute CDR. Write your name, the date and the time-slot on the
> disc with a list of tracks.
> Tape a Tyvek CD sleeve inside a standard file folder. Write
> the slate and track information on the outside of the folder. Put a
> code number on the folder tab: YYMMDD-T (year-month-day, time slot;
> example 050720-night)
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