Presentation by Gianni Pavan

CIBRA - Centro Interdisciplinare di
Bioacustica e Ricerche Ambientali
Università di Pavia, Italy
Go digital
Gianni Pavan
[email protected]
www.unipv.it/cibra
Short history
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Bioacoustic research started in 1980 at the Entomology Lab
Initial focus on bird songs (individual and species recognition)
Research required new analysis tools
1980-1988 First experiments in digital sound analysis, storage and
retrieval
(recording still on analog tape)
1986 First PC based sound analysis system
1988 First stand-alone full digital spectrograph KAY 5500
1989-1997 Adoption of DAT, digital transfer to PC
1990 First PC based real-time sound analysis required DSP
1991 Real-time analysis on simple PC, 1994 real-time on laptop
1998- Direct digital recording to PC
Recording media:
• 1980-1990 analog tapes
• 1991-1997 DAT tapes (now entirely copied to HD and DVD
• 1998-now HD recording on PCs
1980: 64K RAM, 640K floppies, 40 minutes for 1 second bw spectrogram
1985: colour spectrograms in 5-10 minutes
1987: spectrograms printed by a normal
PC on normal paper
1990: real-time on a standard i486 PC
1994: real-time on a cheap laptop!
Now: multiple channels at 192K sampling
Now 1 second spectrogram
computed in less than 50ms
…just recording here…
Tomorrow ?
Advantages of PC recording
•No intermediate passages
•Duration limited only by inline storage
•Sampling rates up to 1MHz (with suitable AD)
•Multiple channels (easy to manage up to 8 ch at 192kHz)
•Automatic recording, continuous, on timer, on events
•Remotely (wired or wireless) controllable
•Automatic filenaming
•Logging of recordings, date/time, position, settings, failures, etc
•Logging of metadata & user information
•Recording from distributed network of PCs
•Real-time visualization
•Join audio and video (work in progress)
Problems…
•Bulky and more complex to operate than just pressing
•Maybe less reliable than a stand-alone recorder
•Powering for continuous operation (batteries, solar panels)
SIRENA_20020713_170000_440453_0084334_2CH96K2400H44_2V_TAP_[….].wav
Cuts have the same name+”cut_hhmmss”+ filter/editing info
[….] may include additional info, checksum, archival code, etc
…long term environmental monitoring with statistical analysis
noise levels, acoustic biodiversity, unexpected events
Regardless of the “recorder” you’re using…
You must be aware of features rarely documented on spec sheets of
consumer/prosumer products
The quality of analog front-end (microphones and preamplifiers) in
relation to your specific task
Microphones’ self-noise
(other than freq. response, linearity and directivity)
Preamplifier’s noise
The quality of A/D converters and related electronics
Sampling rate and aliasing and ….
AD OVERLOAD
0
Analog overload “brickwalling”
dB
aliasing
16bit
-96
Mic noise
Pre noise
AD noise 24bit
-144
0
Fs/2 (Nyquist)
Fs=48,96,192kHz
Soundscape recording
Telinga EM23
Edirol UA25
LowPower Laptop
Additional LiIon battery
Optional
solar panel
MOTU Traveler
8channels 192K
battery powered
Rode NT1A 6dBA self-noise
CoreSound Mic2496 preampli&AD
PocketPC with 4GB CF card
CoreSound PDAudio CF card
Live2496 software
Pocket can be replaced by MT2496
M-AUDIO MicroTrack 2496 less than 400$
Records to CF, up to 96 kHz, mono or stereo
Good frequency response and antialiasing
Bad phantom powering
Hissy preamplifier, requires high-output mics
or external preamplifiers or external AD
Other compact choices:
Edirol R01, R09
Marantz PMD 660
Fostex FR2-LE coming soon
Larger choices:
Sound Devices 702 CF only 722-744 CF+HD
Fostex FR2 – excellent for 192K recording
Marantz PMD 671
TASCAM HD-P2
Rode NT1A
SoundDevices 722
the quietest microphones and the best recorder I ever used
The weakest point of SD 722 is when running at 192kHz
Most researchers don’t care enough about the
performances and features of the equipment they
use…
Recordists are more concerned…
Some $$$ amateurs have top quality equipment
We can provide hints and some tests, but we can’t
test all the equipment choices now available…
We need to develop a common methodology for
testing the equipment we use