In a real-world context, sirens warned people of impending air-raids during wartime. With more peaceful times, most sirens serve as a civil warning system, such as in the case of an approaching natural disaster. Fire departments also use air-raid sirens in the case of fires or serious accidents.
It is theorized that, as Alessa Gillespie was pulled from the fire, the sirens of rescue vehicles wailing around her (or the air-raids of the Fire Department during the fire) became a connection to this "initial point" of her suffering, later integrating the sound into her painful memories and emotions.
As with much of the symbolism, it's possible these sounds have snaked their way into the Silent Hill series, as each time the siren wails, the darkness comes forth to take over Silent Hill and transform it into the Otherworld, or inverse as it "ends" the current nightmare.
|Silent Hill siren|
|The siren in Silent Hill|
The siren is first heard as Harry Mason enters an alleyway where he is confronted with pure horror at the beginning of the game. It later appears several more times.
- Midwich Elementary School - The sound is heard while Harry enters the Clock Tower of the playground. When he exits the clock tower, the school has turned into the Otherworld. After the defeat of the Split Head, the siren rings out as Harry comes back to the Fog World.
- Alchemilla Hospital - During Harry's first conversation with Lisa, the siren sounds and Harry loses consciousness.
- Green Lion Antiques - Harry again hears the siren when he visits the "other church" hidden in the store. Because of a strange conversation he has with Lisa Garland just before, Harry thinks he is hallucinating.
- Central Silent Hill - Shortly after Harry speaks with Lisa Garland to learn how to access the lake, Harry has to kill the Floatstinger at the top of the Post Office in front of Alchemilla Hospital. After this battle, the siren is heard again.
- Resort Area - As Harry crosses the Sandford Street bridge, the siren is heard for the last time in the game. Harry nearly losses his consciousness, but he manages to stay on his feet and witnesses the transition to the Otherworld.
|Silent Hill 2 siren|
|The siren in Silent Hill 2|
- Blue Creek Apartments - In the battle against Pyramid Head in an old water-logged stairwell, James Sunderland hears the siren in the final few seconds. Pyramid Head leaves during the long wailing note, and opens James's path to the other side of the blocked street, where he meets Laura.
- Brookhaven Hospital - After the battle against Flesh Lip, the siren rings out once more. James collapses and is transported to the Otherworld version of Brookhaven Hospital.
Chronologically speaking, this is the first time the siren is heard. After Travis Grady saves Alessa from the fire in the Gillespie house, he collapses outside; at the same time, emergency sirens can be heard and seconds later the typical civil defense siren-sound starts, probably to warn the inhabitants of Silent Hill of the spreading fire that later destroys six houses in the business district of Central Silent Hill. Later, it appears each time Travis sees Alessa.
- Cedar Grove Sanitarium - The siren sounds again after Travis defeats the monstrous version of his mother.
- Artaud Theater - Alessa arrives and kicks the dead body of the Caliban. The sirens sound again, and Travis passes out.
- Riverside Motel - Again, Travis defeats a monstrous version of his father, Alessa arrives, and the siren sounds.
During each transition to the Otherworld, the baleful sound of the early warning system rises in pitch to be cut out at its apex, when the world shifts over. Later on, it is revealed that the sound is actually reminiscent of an electroconvulsive therapy machine powering up; this is only revealed if the player obtains the "Hospital" ending.
In Downpour, Murphy Pendleton accidentally sets fire to a restaurant and activates the sprinkler system to extinguish the fire. This triggers an alarm and it is transported into the Otherworld. The siren can be heard briefly in St. Maria's Monastery when trying to walk over the wooden plank.
Additionally, sirens of patrol vehicles can be heard around the town.
The siren is also heard in some certain places that are already in the Otherworld's presence, most notably in the Centennial Building Otherworld.
|Silent Hill film siren|
|The siren in the film|
Its hollow tones reverberates from its central sound generator atop the church in Central Silent Hill.
- Though it is thought that Valtiel may be the being that is in charge of the shift between the worlds, the siren sound is absent in Silent Hill 3.
- The game Siren (also known as Forbidden Siren in some countries) features an imaginary village named Hanuda, where after an inadvertently interrupted ritual, a siren is heard all over the town similarly to what happens in Silent Hill, transforming the world into a nightmare and summoning the inhabitants of the town to immerse themselves into the sea, where they turn into deadly monsters. The connection with the siren from Silent Hill is even clearer as the creator of Siren is Keiichiro Toyama, creative director of Silent Hill.
- The same siren that is heard in the film can also be heard in the MMORPG Dead Frontier. The siren blares when zombies start attacking the outpost and only stops once the outpost attack is finished.
|Eric - Tina - Bill - Jessie - Ryan - George - Emilie Anderson - Frank Anderson - Michelle Anderson|
Hanna - Lorraine - Captain - Scott Fairbanks - Greys
|Creeper - Double Head - Greedy Worm - Gum Head - Hummer - Insane Cancer - Mama - Numb Body - Nurse - Phantom - Pyramid Head - Robbie the Rabbit - Scraper - Split Worm - Toadstool - Tremer - Tuberculosis|
|Brookhaven Hospital - Central Square Shopping Center - Jacks Inn - Labyrinth - Lakeside Amusement Park - Silent Hill Historical Society - Spiral Staircase - Toluca Lake - Toluca Prison|
|Flashlight - Fog World - Little Baroness - Monster - Otherworld - Radio - Real World - Siren - Welcome Sign|
|Rose Da Silva - Christopher Da Silva - Cybil Bennett - Dahlia Gillespie - Thomas Gucci - Anna - Christabella - Sharon Da Silva - Alessa Gillespie - Dark Alessa|
|Sister Margaret - Eleanor - Colin - Lisa Garland - Jennifer Carroll|
|Pyramid Head - Creeper - Armless Man - Colin - Nurse - Grey Child|
|Brahms - Brookhaven Hospital - Church - Da Silva House - Gans County - Grand Hotel - Midwich Elementary School - Nathan Drugs - Pete's Bowl-O-Rama - Sacrificial Chamber - Silent Hill, West Virginia - Smitty's - Toluca County Archives - Toluca County Mining Museum - Toluca County Orphanage - Toluca Lake|
|The Brethren - Monster - Flashlight - Manifestation - Otherworld - Fog World - Real World - Siren - Great Knife - Welcome Sign - Brethren Symbol|
|Heather Mason - Christopher Da Silva - Vincent Cooper - Claudia Wolf - Leonard Wolf - Dark Alessa - Douglas Cartland - Alessa Gillespie|
|Rose Da Silva - Dahlia Gillespie - Suki - Travis Grady - Order Soldier - Detective Santini - Mannequin Girl|
|Armless Man - Delusion - Leonard Wolf - Lobotomy - Mannequin Monster - Memory of Alessa - Missionary - Nurse - Pyramid Head - Valtiel|
|All Hallows High School - Brookhaven Asylum - Central Square Shopping Center - Jacks Inn - Sanctuary - Silent Hill, West Virginia - Lakeside Amusement Park|
|The Brethren - Halo of the Sun - Monster - Manifestation - Otherworld - Fog World - Real World - Robbie the Rabbit - Seal of Metatron - Siren - The Order - Great Knife - Welcome Sign|