At this point, I’d need something which can handle 96kHz or even better 192kHz sample rate in Audacity.
I’ve found some cheap USB adapters with a mic in and headphones out, though I don’t know if they’d handle such a high sample rate (not listed in their features).
At this point I’m stuck and I don’t want to spend way over $60, so I’d need either a workaround or some tips from you.
After all I’ll just need to view those above frequencies in Audacity’s spectrum, not listen to them
For up to 20 kHz you only need a sample rate of 44100 Hz. Providing that the analogue components are up to the job, 44.1 kHz sample rate can handle a 20 kHz signal comfortably. 48000 Hz sample rate will let you go to over 22 kHz signal frequency, but with the same proviso that the analogue electronics will go that high.
It is not uncommon for sound cards to cut off not much above 20 kHz, even if they are capable of running at sample rates of 96 kHz or more. (after all, they are “sound” cards, so they are likely to be optimised for “sound” rather than ultrasonic frequencies).
I’d have a go with whatever sound card you currently have, then take it from there.
If you can get the signal up to “line level”, then even a cheap Behringer UCA 202 USB interface will give very respectable performance up to 20 kHz signal frequency
I know that using a 48kHz sample rate would be able to let me see frequencies up to 24kHz on the spectrogram, however I was aiming at something higher, like 50kHz frequencies.
Apparently that Panasonic mic model is able to pick up (http://www.wildlife-sound.org/equipment/technote/micdesigns/ultrasonic.html) off-label (not specifically intended for this use, maybe due to project defects or filters) something close to that range, or at least I’ve got nothing better on hand which is known to perform in that way.
That’s why I asked for USB sound cards with a sample rate of 192kHz or 96kHz and, as you pointed out, for one which doesn’t automatically cut off frequencies above 20kHz.
Yes, the Panasonic WM61 is the best bet that I can think of as an inexpensive solution. I can go with that article’s conclusion: “There are no guarantees as to frequency response which is unspecified at ultrasonic frequencies, but it appears to work in practice.”
The next problem is amplifying the signal. Very cheap USB devices (like those little “thumb drive” sized widgets) are likely to have “a lot” of noise in the upper frequency range, which probably rules them out. So you’re after something cheap, but not too cheap
One of the few mainstream inexpensive 96 kHz USB devices that I know of is the Soundblaster XFi Surround. I’ve not used one of these, but from what I can gather the drivers for the XFi series can be a bit problematic and some users have had trouble getting them to play nicely with Audacity. I’ve not found any specification for the audio frequency response for this device. Perhaps you can find a local retail outlet that has a good returns policy? Unfortunately we do not have a review on this forum for the XFi surround.
