Custom-generated alarm tone - thoughts?

User Created Fire Alarm Media
1

(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))))

  • Click “Apply”

Love to know your thoughts on it.

2

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?

3

It’s a linear sweep, and yes it does go ±1590 hz from the centre frequency. The command itself is in Lisp.

4

This seems similar to how Simplex’s old multitone TrueAlerts generated their horn tone, but with different frequencies
IMG_6533

5

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.