About the 20 kHz tone
20,000 Hz is the textbook upper limit of human hearing, mostly reached only by children. Most adults hear nothing, and many headphones and speakers can't reproduce it anyway. Keep the volume low, since you can't judge loudness by ear up here.
A 20,000 Hz sine wave completes 20,000 cycles every second; each cycle lasts 0.050 ms, and the sound wave is about 1.7 cm long in air.
Start with the volume low and raise it slowly. Use the slider to move away from 20,000 Hz, or try another preset: 20 Hz · 40 Hz · 50 Hz · 60 Hz · 100 Hz · 256 Hz · 432 Hz · 440 Hz · 528 Hz · 1,000 Hz · 8,000 Hz · 15,000 Hz · 17,400 Hz.
Questions
How do I play a 20,000 Hz tone?
Press Play above. The generator starts at exactly 20,000 Hz as a pure sine wave; you can change the wave shape and volume.
Why can't I hear 20,000 Hz?
Your speakers or headphones may not reproduce it, the volume may be too low, or it may be outside your hearing range. Very low and very high tones are the hardest.
Is it safe to listen to test tones?
At a comfortable volume, yes. Start quiet, and stop if anything feels uncomfortable.
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