The phrase "ambulance siren" refers to the loud, high-pitched sound made by an ambulance to alert people on the road that it is approaching quickly. Full definition
Ambulance sirens went off, and in the darkness no one knew how to find their way out of the complex,» he said. (cnbc.com)
In my bedroom, I can hear my neighbor's small dog barking, the bleating horn of tugboats on the East River, the wail of ambulance sirens and the constant drone of the freeway a block away. (mindbodygreen.com)
But the rainbow comes out, as my toddler makes ambulance siren pitch sounds right in my ear, and talking toddler gibberish. (attachmentparenting.org)