# what makes the siren sound?

**URL:** <https://boards.straightdope.com/t/what-makes-the-siren-sound/263603>\
**Category:** Factual Questions\
**Created:** [September 8, 2004, 5:12am UTC](https://boards.straightdope.com/t/what-makes-the-siren-sound/263603 "2004-09-08T05:12:50Z")\
**Posts on this page:** 3\
**Page:** 1

<div class="post-metadata">

**Author:** ![vinniepaz](https://avatars.discourse-cdn.com/v4/letter/v/b4bc9f/32.png) [@vinniepaz](https://boards.straightdope.com/u/vinniepaz)\
**Post date:** [September 8, 2004, 5:12am UTC](https://boards.straightdope.com/t/what-makes-the-siren-sound/263603/1 "2004-09-08T05:12:50Z")

</div>

i mean the one from police and firetrucks and ambulances. is it a recording or is there actually something making the sound? if its a recording, what created that sound originally?

---

<div class="post-metadata">

**Author:** ![Larry\_Mudd](https://avatars.discourse-cdn.com/v4/letter/l/f14d63/32.png) [@Larry\_Mudd](https://boards.straightdope.com/u/Larry_Mudd)\
**Post date:** [September 8, 2004, 6:46am UTC](https://boards.straightdope.com/t/what-makes-the-siren-sound/263603/2 "2004-09-08T06:46:19Z")

</div>

An electronically generated waveform is amplified.

Here’s a [simple circuit diagram](http://www.techlib.com/electronics/noisemakers.html).

Of course emergency service sirens are more complicated, with varying settings, etc, but the principle is the same.

---

<div class="post-metadata">

**Author:** ![sturmhauke](https://avatars.discourse-cdn.com/v4/letter/s/e47c2d/32.png) [@sturmhauke](https://boards.straightdope.com/u/sturmhauke)\
**Post date:** [September 8, 2004, 6:48am UTC](https://boards.straightdope.com/t/what-makes-the-siren-sound/263603/3 "2004-09-08T06:48:13Z")

</div>

There’s a horn with a rotating disk inside. The disk has holes punched in it, so that when air passes through it makes the siren noise. Furthermore, the sound is actually a bunch of discordant notes, kind of like pressing a hand’s width of piano keys all at the same time.