Can audacity produce sound above 20 kHz? If so, what hardware is needed to produce and play it?
Yes. Digital audio requires a sample rate of at least twice the audio frequency so a sample rate of 44.1kHz (audio CDs are 44.kHz) or higher will work. That’s the only digital limitation. You might want to go with 96kHz or 192kHz.
Most soundcards and audio amplifiers can go to 20kHz. You’ll need a good tweeter but most good hi-fi speakers go to at-least 20kHz. The “traditional” human hearing range is 20Hz -20kHz so most audio/hi-fi equipment covers that range.
Can audacity produce sound above 20 kHz?
What’s your actual application? Your question reads like you want super good fidelity in a live performance so you can do serious editing and effects later, but it’s also the question from people wanting to produce subliminal transmissions or ultra-sonic carrier work. All very different, but all needing the sound channel to reach 20,000Hz and keep going.
Ultrasonic carrier work for one example demands your sound channel go up to 20,000Hz and then keep going to double the work frequency. If you wanted to park AM radio quality sound up there, the channel would have to go up to 30,000Hz, correctly and cleanly just to get it all in. I don’t know any sound cards which will do that.