Fimmtudaginn 30. desember 2010 dýfði ég hljóðnemum í sjóinn í Sundahöfn. Ekki var við neinu merkilegu að búast. Þrjú skip voru í höfn, Wilson Brugge, Dettifoss og Goðafoss. Vélahljóð frá ljósavélum yfirgnæfði allt. Heyra mátti að dælur fóru í gang í skipunum og einstaka bank, líklega þegar einhverju var slegið utan í skipssíðuna. Í gegn um háfaðan má svo greina nokkra skelli sem liklega koma frá einhverri skel, hugsanlega kræklingi. Það var ekki fyrr en heim var komið og Spectrogram forrit hafði gert hljóðritið sýnilegt að það sást eitthvert undarlegt hljóð á 50Khz.
Þess skal getið, að börn með bestu heyrn ná líklega upp í 22Khz og miðaldra fólk yfirleitt ekki hærra en 14Khz. Þarna var því eitthvað sem var langt fyrir ofan heyranlega tíðni. Hljóðið var mjög reglulegt og aðeins bundið við afmarkaða tíðni eða á milli 48Khz til 51Khz. Var því óhugsandi að þetta kæmi frá einhverri skepnu. Það var því líklegt að einhver hefði gleymt að slökkva á dýptarmæli í þetta sinn. Miðað við stefnu virtist það koma frá Wilson Brugge.
Hljóðið var nokkuð áhugavert. Ég ákvað því að nota tæknina til að gera hljóðið heyranlegt. Til þess þurfti að hreinsa út öll önnur hljóð og suð fyrir ofan og neðan 50 khz. Þá var tíðnin lækkuð með hraðabreyti þar til hljóðið var komið í 4khz. Við þetta lækkaði líka tifhraði hljóðsins svo nú heyrist tíst með löngu millibili í stað þess að vera u.þ.b. eitt á sekúndu.
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Undersea recording in Sundahöfn harbor.
Most of the audible sound was a noise from Motor Generators in the ships. When the recording was viewed in Spectrogram it was a notible 50kHz Echo Sounder signal.
Using pitch control the signal was downgraded to audible 4kHz. At the same time, all other sounds from ships engine and „digital sampling noise“ above 75kHz was erased.
Recorder: Korg MR1000 24bit/192khz
Mic: Aquarian H2a-XLR Hydrophone.
Pic: Canon 30D (see more pictures and spectrogram)
Audible sound pollution in the Harbor.
Sækja mp3 skrá ( 192kbps / 4Mb )
Echo Sounder at 4kHz (very slow activity).
Sækja mp3 skrá ( 192kbps / 5Mb )
HLJÓÐMYND - SOUNDIMAGE 
Magnús, mér dettur helst í hug að þú hafir náð sambandi við geimverur þarna 😉 Nokkur einkennilega útlits bankað upp á hjá þér nýlega?
Hehehe, ég held að ég þurfi ekki heimsókn geimveru.
Aðeins næmari skynfæri.
Really like the pitched down sample, nice drone with interesting textures.
I thought about buying a Aquarian H2, so whats your impression?
Thanks Magnus
These microphones opened a whole new world for me. They are very sensitive. For example, I have record a silence in this same harbor (Sundahöfn). I could hear the birds land on the sea far away, also lots of strange clicks (may come from shells or shrimps). In full recording quality 24bit/192Khz I could detect the size of the port in the echo as I was standing in a large hall.
Aquarian microphones are not expensive http://www.aquarianaudio.com. They are cheaper than http://www.dolphinear.com. and lots cheaper than http://www.sonar-surround.de.
But I have no comparison so I do not know if the price can tell something about the quality.
Services are good in Aquarian. I ask if the microphone could withstand boiling because I was thinking to put them in hot springs. Robb Nichols at Aquarina sent me a video where he test it and boil a microphone in 20 minutes without damaging the microphone.
I can highly recommend Aquarian microphone. I ordered them with 9-meter cable.
PS.
I see Noise Jockey has also received a Aquarina Mic
http://www.noisejockey.net/blog/2011/01/12/hydromotordrone/
I’m actually thinking about ordering an H2a in the beginning of next week.
Did you buy the contact mic adapter as well when ordering your H2a? Am a bit curious of how the H2a performs as a contact mic.
inovember: When you talk about “contact mic”, are you then talking about H2a “plug in power mic” (PIP mic) with 3,5mm plug?
I ordered H2a-XLR not H2a.
Afterward I think I should have ordered H2a and also the H2a to XLR adapter because I have recorders with both options.
I think the only problem with H2a is that PIP amplifiers have normally less quality, more noise and less amplification than professional phantom power amplifiers. But I think your Sony recorder have probably one of the best PIP amplifier around. I think then if you also order H2a to XLR adapter it will let them work with Phantom Power. But I am not sure.
They say XLR type works only with 48V Phantom power, but then I think a XLR to 3.5mm PIP adapter will not work!
Honestly, I think you should send a question to AquarianAudio.
I actually sent them a few questions last night concerning this. If the H2a-XLR can be connected to the 3,5 jack on my D50 using the XLR -> 3,5mm adapter I’m going for that. I’d like to be able to connect the H2a to my Rolls PB224 as well as to the D50 as that opens up more possibilities when it comes to using the H2a together with other mics as well as keeping the possibility of having portable gear just using the D50 and the H2a.
I guess I’ll have to wait and see what they say before ordering. I’ll post the answer to my question here, perhaps you can just order the XLR -> 3,5mm adapter as well.
Thanks for this. I opened the XLR plug, if there was a circuit to handle 48 volts. But there was nothing. The wires goes directly to the plug.
It will be interesting to know if it is possible to use 3,5mm PIP adapter to h2a XLR.
If it really works, I will order or make this adapter.
Hi Magnus,
I got an answer from Robb at Aquarian, he writes: „Yes, the H2a-XLR will work with both the PB224 and directly with your Sony D50. Our H2a standard (3.5mm out) and the H2a-XLR is actually the same hydrophone now. The buffer amp is designed to work with a very wide range of bias supplies. There may not be any advantage to using the PB224, and yet it may lower noise and increase sensitivity and dynamic range. I am sorry to be so vague, but plug-in power supplies (and to a lesser extent, even phantom power supplies) have such variation in voltage and current that it is hard to know without experimenting.“
So we both just have to get our hands on a XLR -> 3,5mm plug to use it with PIP-plower from our handhelds. Nice!
Thanks for this.
This is clearly an incredible microphone.
I obviously need to get the H2XLRadp3.5 adapter.
Really interesting recordings. I feel really sorry for the marine life that must be having their lives disrupted by these noises.