How loud is a police siren?
California requires emergency vehicle sirens, including those on police cars, to reach at least 120 dB(A) (Class A) or 115 dB(A) (Class B) measured 3 m straight ahead. Off to the side the required level is lower, down to 113 and 108 dB(A) at 50 degrees.
- Level
- 115–120 dBAA-weighted sound level
- Distance
- 3 m3.0 m (9.8 ft), straight ahead of the siren
- Daily limit
- 9 s a dayNIOSH, at the loud end
- Versus conversation
- 316,228× energyabout 45.3× as loud
What the numbers mean
How it was measured. California minimum A-weighted output for emergency vehicle sirens at 3.0 m on axis: Class A 120 dB(A), Class B 115 dB(A). These are legal minimums; off axis the minimums fall to 113 and 108 dB(A) at 50 degrees.
California's Highway Patrol regulations define two classes of siren by their A-weighted output at 3.0 m (9.8 ft). On the siren's axis a Class A siren must reach at least 120 dB(A) and a Class B at least 115 dB(A). The minimums fall away to the sides, to 117 and 112 dB(A) at 30 degrees and 113 and 108 dB(A) at 50 degrees, which reflects how sirens throw sound forward.
Electronic sirens must have a wail function, with an undulating pitch of 10 to 30 cycles a minute, and may have a faster yelp. During the wail the level may drop no more than 10 dB(A) below the table values at the quietest part of each cycle. Measured siren signals on Polish emergency vehicles were 104 to 108 dB(A), at a distance the study does not state.
How long is safe?
NIOSH recommends no more than 9 s a day at 120 dBA (28 s at 115). OSHA's legal limit is 7 min 30 s.
| Level | NIOSH limit (85 dBA, 3 dB rule) | OSHA limit (90 dBA, 5 dB rule) | UK/EU 80 dB(A) action value reached after | UK/EU 85 dB(A) action value reached after |
|---|---|---|---|---|
| 115 dBA | 28 s | 15 min | 9 s | 29 s |
| 120 dBA | 9 s | 7 min 30 s | 3 s | 9 s |
Times are for a whole day’s exposure, with the rest of the day quiet. The workplace limits were written for adults at work, not for children. Work out a mixed day with the noise dose calculator.
Pets
Many dogs howl at sirens; the sound is brief and usually harmless.
Protecting your hearing
Cover your ears or turn away if a siren starts right beside you; the exposure is short. Officers who run sirens often should keep windows closed and consider hearing protection compatible with radios.
Earplug and earmuff ratings (NRR in the US, SNR in the UK and EU) are lab figures; real-world protection is usually lower. How to read the ratings.
Compared with sounds nearby
Using midpoints of each range. Energy multiplies by 10 every 10 dB; perceived loudness roughly doubles (why).
- Dog barking (104–118.9 dBA max): this has about 4× its sound energy and sounds about 1.5× as loud.
- Fireworks display (108–116 dBA max): this has about 3.5× its sound energy and sounds about 1.5× as loud.
- Formula 1 Grand Prix (121.8 dBA max): it has about 2.7× the sound energy of this and sounds about 1.3× as loud.
- Vuvuzela (113–131 dBA max): it has about 2.8× the sound energy of this and sounds about 1.4× as loud.
- Normal conversation (55–70 dBA): this has about 316,228× its energy and sounds about 45.3× as loud.
Questions
How loud must a police siren be?
In California a Class A siren must produce at least 120 dB(A) at 3 m straight ahead, and a Class B at least 115 dB(A).
Why does a siren sound quieter from the side?
Sirens project forwards; California's rule allows the level to fall to 113 dB(A) for Class A at 50 degrees off axis.
Sources
- Cal. Code Regs. Tit. 13, § 1028 - Performance Requirements, California Code of Regulations (Legal Information Institute, Cornell). Supports: dB_high 120 (Class A), dB_low 115 (Class B) on axis.
Sound Level, dB(A) Class A Class B 0 120 115
Checked 2026-11-03. - Cal. Code Regs. Tit. 13, § 1028 - Performance Requirements, California Code of Regulations (Legal Information Institute, Cornell). Supports: 3.0 m distance.
Table I. Minimum A-Weighted Sound Level at 3.0 m (9.8 ft)
Checked 2026-11-03. - Cal. Code Regs. Tit. 13, § 1028 - Performance Requirements, California Code of Regulations (Legal Information Institute, Cornell). Supports: off-axis minimums.
30 117 112 40 115 110 50 113 108
Checked 2026-11-03. - Cal. Code Regs. Tit. 13, § 1028 - Performance Requirements, California Code of Regulations (Legal Information Institute, Cornell). Supports: wail cycle rule.
The sound level shall not drop more than 10 dB(A) below the required values in Table I during the lowest portion of any cycle.
Checked 2026-11-03. - Cal. Code Regs. Tit. 13, § 1028 - Performance Requirements, California Code of Regulations (Legal Information Institute, Cornell). Supports: wail rate.
The wail function shall have an automatic undulating pitch rate of not less than 10 nor more than 30 oscillations per minute.
Checked 2026-11-03. - Occupational exposure to noise from authorized emergency vehicle sirens, International Journal of Occupational Safety and Ergonomics (Górski, 2014), abstract via Europe PMC. Supports: Polish siren measurements.
Measured A-weighted SPLs of those signals range between 104 and 108 dB.
Checked 2026-11-03.
This page is general information, not medical advice. If you have ringing in your ears, muffled hearing or any change in your hearing, see an audiologist or your doctor.