(First post, so bear with me)
Recently, I’ve tried to make my own fire alarm horn sound. I tried a few things but ended up settling on a sine wave swept at 60 Hz with an effective frequency range of 2500 to 5000 Hz.
Since I can’t upload audio files, to see what I mean, you can do this if you have Audacity (it’s a free and open-source audio editing software):
- In Audacity, go to “Tools” > “Nyquist Prompt”
- Copy and paste this below where it says “Enter Nyquist command”:
(hzosc (sum 3750 (mult 1590 (osc-tri 60))))
Love to know your thoughts on it.
Oh that’s a pretty cool method to generate tones. Sounds a lot like a System Sensor tone for their horns.
I’m not hugely knowledgeable with Nyquist, but judging from the logic of the pseudocode, does this just start at a base frequency of 3750 hz and sweep up and down by 1590 hz at 60 hz?
It’s a linear sweep, and yes it does go ±1590 hz from the centre frequency. The command itself is in Lisp.
This seems similar to how Simplex’s old multitone TrueAlerts generated their horn tone, but with different frequencies
You can actually generate that in Audacity as well with a Nyquist command via Lisp:
(hzosc (sum 3050 (mult 650 (osc-tri 120))))
Go into Effect > Distortion > Soft Overdrive, and set “Distortion amount” to 5 and “Output level” to 100.