On 3/31/2016 7:42 PM, Tom Fine (GMail) wrote:
> I agree this topic is more suited to ARSC List, so I will cross-post
> this reply.
>
> Question 1 -- do any birds or ocean mammals produce frequencies higher
> than 48kHz? If no, then 96k sampling rate is just fine.
While not totally up to date,
http://hypertextbook.com/facts/1998/JuanCancel.shtml supplies some answers:
> Frequency Range of Hearing for Humans and Selected Animals
>
> animal frequency (hertz)
> low high
> Humans 20 20,000
> Cats 100 32,000
> Dogs 40 46,000
> Horses 31 40,000
> Elephants 16 12,000
> Cattle 16 40,000
> Bats 1,000 150,000
> Grasshoppers and locusts 100 50,000
> Rodents 1,000 100,000
> Whales and dolphins 70 150,000
> Seals and sea lions 200 55,000
>
> Reference: Encyc. Britannica.
>
> Question 2 -- what are the known uppper limits of sounds captured by
> analog recordings of these animals? I suspect there was no analog
> recording system used capable of more than about 30kHz, but I may be
> wrong. If my suspicion is correct, then, again, 96k sampling rate is fine.
Sennheiser MKH 800 - 30-50k Hz
http://www.wildlife-sound.org/equipment/technote/micdesigns/ultrasonic.html
60 kHz
Bruel & Kjaer mic (very noisy)
4138 - 1/8-inch pressure-field microphone, 6.5 Hz to 140 kHz, 200V
polarization
Designed for very high-frequency measurements in confined spaces.
So a lot of things are doable.
Cheers,
Richard
>
> Finally, a comment. I don't think there is a huge issue with storing
> massive amounts of 96/24 data. First of all, it can be
> lossless-compressed, a variety of ways. Second, disc drives are cheap
> and huge-capacity these days.
>
> -- Tom Fine
>
> ----- Original Message ----- From: "Richard L. Hess"
> <[log in to unmask]>
> To: <[log in to unmask]>
> Sent: Thursday, March 31, 2016 7:20 PM
> Subject: Re: Extended range biologist generated sound recordings
>
>
>> Hello, Nathan,
>>
>> You raise a good question here (but I wonder if this is better on
>> ARSCLIST than ARSCLIB). The short answer is that I suspect each
>> discipline and, in many instances, each instance of that discipline
>> has their own standards.
>>
>> In the analog world, the IRIG instrumentation recorders offered
>> excellent options to record infrasonic and ultrasonic sounds and other
>> similar data.
>>
>> My major experience in IRIG tapes has been for seismic purposes. I
>> have digitized some audio recordings of a seismic survey of Flathead
>> Lake in Montana and the USGS tapes preceding, during, and following
>> the 1980 eruption of Mt. St. Helens.
>>
>> One of the nice things about IRIG recordings is that the speeds can be
>> varied and everything else stays in proper relation (unlike analog
>> audio where the EQ does not follow the speed steps).
>>
>> We looked at the desired output frequency range. The IRIG machines
>> when they record in FM can go down to DC, so we had to define a lower
>> cutoff obtain very expensive DC-capable instrumentation converters.
>> For the Mt. St. Helens material, which was recorded at 15/32 in/s, we
>> digitized at 60 in/s, raising the lowest frequencies 128x so that our
>> converters that were flat to below 10 Hz provided real-time flat
>> response down to below 0.1 Hz which was more than adequate. We were
>> able to capture above 40 kHz (using a 96 kHz sample rate) which
>> resulted in a HF limit of about 300 Hz. The client was interested only
>> in signals up to about 60 Hz or so. Since they were not going to
>> retain the original tapes, I made a case that I could see information
>> up to about 180 Hz, so they kept a set of the 300 Hz wide bandwidth
>> digital copies.
>>
>> Using speed to slide the desired signal bands into the available
>> signal bands is a powerful tool to making excellent digital copies of
>> IRIG-type tapes at relatively low cost.
>>
>> Seismic material is analyzed by graphical plots and digital systems,
>> so the speed variations were of no consequence.
>>
>> Interestingly, I was contacted by a Brazilan musician who wished to
>> use some of the sounds in a musical piece. I contacted my clients and
>> obtained permission for him to use it.
>>
>> This reminds me of the use of Roger Payne of Woods Hole giving Judy
>> Collins a tape of whale sounds back in the late 1960s or 1970 which
>> came out accompanying a whaling song on Collin's November 1970 album,
>> "Whales and Nightingales." I am not certain, but I think the ones that
>> Collins uses are sped up 2x.
>>
>> Working with ultrasonic material could be handled the same way.
>>
>> At both ends of the spectrum, the spectrum shifting does not impede
>> digital analysis and allows human audible analysis. As long as the
>> spectrum shifting is properly documented and carefully done, it should
>> be fully reversable.
>>
>> Cheers,
>>
>> Richard
>>
>>
>>
>> On 3/31/2016 6:24 PM, Nathan Coy wrote:
>>> For a while now I have been wondering about how organizations are
>>> approaching storage, access, and format for extended frequency range
>>> recordings related to birds (Cornell), ocean mammals (MBARI), and so on.
>>> Not so much audiophile music recordings per se, but recordings that are
>>> analyzed spectrally outside of human hearing for scientific research
>>> purposes. Is there a recommended or emerging sample rate and bit depth?
>>> Much like in many ways 96kHz 24 bit has been mostly adopted when
>>> appropriate. I am curious if individuals working within organizations
>>> that
>>> are collection and generating these types of recordings are noticing
>>> trends
>>> and so on. Often there are massive amounts of sound being recorded also
>>> which seems like it could present management challenges.
>>>
>>> It seems like this is a significant research area and relevant to sound
>>> recording collections at many institutions.
>>>
>>> Thanks,
>>>
>>> Nathan
>>>
>> --
>> Richard L. Hess email: [log in to unmask]
>> Aurora, Ontario, Canada 647 479 2800
>> http://www.richardhess.com/tape/contact.htm
>> Quality tape transfers -- even from hard-to-play tapes.
>
--
Richard L. Hess email: [log in to unmask]
Aurora, Ontario, Canada 647 479 2800
http://www.richardhess.com/tape/contact.htm
Quality tape transfers -- even from hard-to-play tapes.
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