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tips:recording_ultrasound [2023/08/28 22:37] – created mrkva | tips:recording_ultrasound [2023/08/31 16:27] (current) – mrkva | ||
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====== How to record ultrasound (with LOM microphones) ====== | ====== How to record ultrasound (with LOM microphones) ====== | ||
- | Ultrasound refers to sound waves with frequencies higher than the upper audible limit of human hearing. This means that we can't perceive them, but fortunately, | + | {{: |
- | Our LOM Uši and mikroUši microphones can capture a significant portion of the ultrasonic range above 20 kHz. With the assistance of open-source software like [[https:// | + | Ultrasound refers to sound waves with frequencies higher than the upper audible limit of human hearing. This means that we can't perceive them, but fortunately, |
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- | Let's start with a very basic ultrasonic generator – our keys. By shaking a set of keys, you can generate bursts of sound reaching almost 80 kilohertz! However, don't let the audible part of the sound fool you; there' | + | |
To get started, you'll need a recorder capable of recording at a sample rate of 96 kHz or 192 kHz. The latter is preferred. The theoretical limit you can capture with a 96 kHz sample rate is half of that – 48 kHz. With a 192 kHz sample rate, you can record sounds up to 96 kHz. Keep in mind that this is a theoretical limit based on [[https:// | To get started, you'll need a recorder capable of recording at a sample rate of 96 kHz or 192 kHz. The latter is preferred. The theoretical limit you can capture with a 96 kHz sample rate is half of that – 48 kHz. With a 192 kHz sample rate, you can record sounds up to 96 kHz. Keep in mind that this is a theoretical limit based on [[https:// | ||
- | Secondly, you'll require microphones capable of capturing ultrasonic content. LOM Uši, mikroUši, and basicUcho series microphones are suitable for recording ultrasonic sounds, and we encourage you to test them for this purpose. In terms of performance (signal-to-noise ratio at higher frequencies), | + | Secondly, you'll require microphones capable of capturing ultrasonic content. LOM Uši, mikroUši, and basicUcho series microphones are suitable for recording ultrasonic sounds. In terms of performance (signal-to-noise ratio at higher frequencies), |
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+ | For your first subject, you can use a very basic ultrasonic generator – keys. By shaking a set of keys, you can generate bursts of ultrasound reaching almost 80 kilohertz! However, don't let the audible part of the sound fool you; there' | ||
Finally, you'll need a computer and software that can "slow down" the ultrasound to the audible range. For this tutorial, I'll be using Audacity, a free and versatile open-source tool. The process is straightforward: | Finally, you'll need a computer and software that can "slow down" the ultrasound to the audible range. For this tutorial, I'll be using Audacity, a free and versatile open-source tool. The process is straightforward: | ||
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To summarize the steps: | To summarize the steps: | ||
- | 1. Configure your recorder to record at the highest possible sample rate – 192 kHz is ideal, while 96 kHz sets the upper frequency limit at 48 kHz. | + | - Configure your recorder to record at the highest possible sample rate – 192 kHz is ideal, while 96 kHz sets the upper frequency limit at 48 kHz. |
- | 2. Set your microphone' | + | |
- | 3. Note that all microphones become directional at ultrasonic frequencies – ensure that the microphone is pointing toward the desired sound source. | + | |
- | 4. Begin recording. At this point, you won't be able to hear the ultrasonic content. | + | |
- | 5. Open the recorded | + | |
- | 6. Now, it's time to "slow down" the ultrasound to the audible range. This depends on your desired outcome. I usually start by setting the track rate to around 16 kHz. | + | |
- | 7. Experiment to find the settings that sound best to your ears. | + | |
- | 8. When exporting from Audacity, I recommend changing the Project Sample Rate (in Audio Settings) from 192 kHz to a smaller value. There' | + | |
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+ | As a real world example, I recorded bats with LOM mikroUši series microphone. You can download the ultrasonic original [[https:// | ||
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+ | Following images illustrate the frequency shift. The spectrograms look practically identical, but notice the frequency range on the right side. Inaudible ultrasonic sounds are now in audible range. | ||
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+ | ===== Interesting links ===== | ||
+ | * [[https:// | ||
+ | * [[https:// |