Gianni,
Of course, 96 or 192 kHz recording has indeed many benefits when your
focus is more on the scientific aspects that you described. What I
meant is that it would be questionable for recordings that are
intended for normal (human) listening.
Regards,
Raimund
--- In Gianni Pavan <> wrote:
>
> Hi all,
> I'd like to underline that recording at 96 kHz may provide
> benefits even if our hears can't hear so high.
> - recordings can be used for scientific uses, not only for listening
> - if you need to measure the time of arrival of an acoustic event on
> two microphones, a doubled sampling rate means double accuracy
> - some species produce high frequency sound (insects, for example) or
> sound with many harmonics extending beyond 20 kHz. In particular when
> recording at short distances.
> - in case of impulsive sounds, such as stridulation, a higher sample
> rate means much better description of the pulses
> - a higher sample rate means more accuracy that could be useful in
> any post processing
> - many recorders and sound boards have poor anti-aliasing filters. a
> higher sample rate is less likely to cause aliasing problems; if any
> aliasing problem occurs, it happens at higher frequencies where it is
> less disturbing
> - most condenser microphones have frequency response well beyond 20
> kHz; with some equalization it is possible to restore high
> frequencies attenuated by the falling response of the mic.
> - in measuring environmental noise high frequencies are extremely
> important. when conducting behavioural experiments in laboratories it
> is very important to monitor any high frequency that could come from
> electronic equipment (TVs, monitors, switching poer units, etc.).
> - some years ago I participated to studies on monkeys where the
> animals were trained to react to specific sounds. but when testing
> them with 44.1kHz recordings the animals did not react. then we
> switched to 96 kHz and the animals reacted with the same frequency as
> with "live" natural sounds. Of course we are not monkeys, but many
> acoustic events have high frequency components that are relevant for
> their accurate identification and description.
> - recording live music made with traditional acoustic instruments, 96
> kHz recordings are much better than at 44.1.
>
> In the case of my Sennheiser K6/ME66 running on the internal battery
> the noise increase begins at 10kHz. I wrote to sennheiser and I'm
> waiting for a reply.
>
> Gianni
>
>
> At 11.57 22/03/2007, you wrote:
>
> >Steve, you wrote:
> >
> > > So here's the question --- what microphones are people using
with the
> > > fancy machines that digitize at 96 and 192 KHz?
> >
> >In my opinion, normal audio recording at 96 or even 192 kHz does not
> >make much sense. It's just some kind of an esoteric or "homeopathic"
> >approach, which might work if one believes in it ;-). As far as I
> >know, there is still no proof that we can hear anything above 20 kHz.
> >The only argument that I would accept is that the anti-aliasing
> >filters in the 96 or 192 kHz sampling mode do not need to be very
> >sharp. A more relaxed (or a higher frequency cutoff) filter will
> >introduce less ringing and phase distortions at the upper frequency
> >limit of our hearing range.
> >
> > > I understand that there are several (very expensive) measurement
> > > microphones that cover the larger frequency range but the ones I've
> > > seen, together with things like the Earthworks microphones, have a
> > > fairly high noise level. (22 - 28 dB A or higher).
> >
> >Yes, it seems to be impossible to design a microphone that provides
> >both a low inherent noise floor and a large bandwidth from 50 Hz up to
> >50 kHz and beyond.
> >
> > > When I visit web pages of manufacturers and view spec's for all the
> > > usual devices people talk about here --- none of them say how the
> > > microphones work in the 25+KHz range.
> >
> >I know of two microphones that try to adapt the 96/192 recording mode:
> >Sennheiser MKH800 and Schoeps MK 21H + CMC 6:
>
><http://www.schoeps.de/E-2004/specs-mk-ccm21h.html>http://www.schoeps.de/E=
-2004/specs-mk-ccm21h.html
> >
> >Both models achieve the extended frequency range simply by boosting
> >the higher frequencies. However, due to physical constraints, the
> >noise floor at the very high frequencies above about 30...40 kHz will
> >also be increased. Therefore, the manufacturers do not specify the
> >poor noise figures at those high frequencies...
> >
> >If you are interested in recording ultrasounds for more scientific
> >purposes (e.g. for bats, rodents or bush crickets), then you should
> >have a look at microphones or bat detectors that have been optimized
> >for that purpose. Avisoft Bioacoustics for instance offers two
solutions:
> >
> >a) Phantom-powered ultrasound microphones for common 96/192 kHz
recorders:
>
><http://www.avisoft.com/usg/microphonesP48.htm>http://www.avisoft.com/usg/=
microphonesP48.htm
> >
> >b) Dedicated laptop (or UMPC [=3D ultra mobile PC]) based recording
system:
>
><http://www.avisoft.com/usg/usg116-200.htm>http://www.avisoft.com/usg/usg1=
16-200.htm
> >
> >Regards,
> >Raimund
> >
> >
> >
> >No virus found in this incoming message.
> >Checked by AVG Free Edition.
> >Version: 7.5.446 / Virus Database: 268.18.16/729 - Release Date:
> >21/03/2007 7.52
>
>
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> Gianni Pavan
> Centro Interdisciplinare di Bioacustica e Ricerche Ambientali
> Universita' degli Studi di Pavia, Via Taramelli 24, 27100 PAVIA, ITALIA
> Phone +39-0382-987874 Fax +39-02-700-32921
> Email
> Web http://www.unipv.it/cibra
>
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> CIBRA organizes the XXI IBAC Congress, Pavia, 15-18 September 2007
> http://www.unipv.it/cibra/xxi_ibac.html
>
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