Definition

The Alarm pattern is a set of auditory cues that humans and animals use to communicate fear. Screams, shrieks, sirens, and yelps all share a set of distinct, rare acoustic features. These features are difficult to produce, which helps alarm cues serve as honest signals of danger (and avoid the boy-who-cried-wolf problem). The more abruptly artists introduce alarm cues into their music, and the more performers intensify the unique features that distinguish them, the more likely we are to experience chills.  

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Mechanism

The Alarm pattern directly activates our amygdala (a brain region that helps us respond to threats). Alarm cues have two key features. First, they concentrate energy in the 3-5 kHz range. This mirrors the resonant cavity of our ear dream and is the part of the audio spectrum to which we are most sensitive. Sounds in this range are especially piercing; opera singers use a squillo technique that brings out a “singer’s formant” around 2.8-3.2 kHz, which helps them project over an orchestra but is also likely why some people say opera sounds like screaming. A second distinguishing feature of alarm cues is rapid amplitude modulation. Whereas normal speech modulates at a rate of 4-5 Hz/sec, screams modulate at 30-150 Hz/sec. This helps makes them especially attention-grabbing.

Technique #1: “Noisy” high-pitch sounds with spectral non-linearities

The first Alarm pattern technique involves high-pitch sounds with frequency features called non-linearities. Non-linearities are produced when a sound system (e.g. our voice box, a synthesizer, a cello) is strained beyond its lower or upper range. You know non-linearities when you hear them; these are “noisy”, intense sounds. They have unusual, unstable technical features like sidebands, warbles, subharmonics, and chaotic broadband energy that appear between or outside the normal harmonics of a voice or instrument. 

In chills-inducing passages, the most reliable ways we see artists pull off this technique are:

• Overblown resonators: atonal screams by talented lead vocalists, abrupt high notes on clarinets and piccolos, sudden trumpet or French horn “squeals” 

• Distorted string instruments: screeching violins at the top of their range, distorted high notes on electric guitar, and even guitar-amplifier feedback 

• Metallic percussion instruments: waterphone, anvil, cymbals, gongs, or chimes

Don’t interpret this technique as a “hack” that automatically results in chills. Just having a vocalist scream as high as they can won’t work. Artistry is required in the set-up, follow-up, and execution. Consult the Frisson 101 page for tips on how other artists have used the Alarm pattern.

Technique #2: “Rough” sounds with rapid amplitude modulation 

The second Alarm pattern technique involves high-pitch sounds with a frequency feature called acoustic roughness. Roughness is like a strobe light effect for sound; rough sounds have rapid fluctuations in loudness, or high modulation rates. We perceive this feature as a rattling or pulsing sensation (think of the buzzing of an alarm clock). 

In chills-inducing passages, the most reliable ways we see artists pull off this technique are:

• Staggered filters: often to make the rate and height of amplitude modulation vary in a rapid non-linear way, typically applied to electronic sounds but also to lead vocals  

• Certain extended vocal techniques: ululation, rapid vibrato, and tonal screams featured on loud, high-pitch, exposed notes

• Certain instrumental techniques: trills, flutter tongue on wind and brass instruments, tremolo string bowing, and certain percussion instruments like the ratchet 

Technique #3: “Beating” dissonance

The third Alarm pattern technique involves highly dissonant intervals where the two tones interfere with each other so much that they create a pronounced beating. This technique is a variant of Technique #2 (roughness) but differs in that it creates a more periodic beating across the two notes in the interval rather than the more constant “rattling” that occurs when one note is distorted.

In chills-inducing passages, the most reliable ways we see artists pull off this technique are:

• Extreme dissonant intervals: especially minor second, tritones, and major sevenths, typically sounded either in the same octave or several octaves apart

• Steady-state sound sources: timbres like held voice, bowed strings, brass or winds, which create more salient roughness than impulse sources like percussion or plucked strings 

• Doubling and added reverb: applied to the instruments sounding the interval to make the dissonance as inharmonic, unstable, and prolonged a possible 

Technique #4: “Siren” sounds with arcing, gliding contours

The fourth Alarm pattern technique involves gliding sounds with a rise-and-fall contour and pronounced, loud peak. These features make sirens especially attention-grabbing and is why they are used for ambulances, police cars, and tornado sirens. Recent research has also shown that arced contours are one of the key ways listeners can tell a real vs. a fake scream.  

In chills-inducing passages, the most reliable ways we see artists pull off this technique are:

• Single, slow arching sounds: gliding sounds that last several seconds, crescendo into the peak, and rise faster than they fall

• Rapid, repeated arching sounds: typically one siren per second repeated 3-4 times, which fall faster than they rise and maintain a loud volume throughout

• Recordings of real-life sirens: samples of air-raid sirens or real-life screams, often played when the rest of the music drops out to make them as jarring as possible

Technique #5: “Whistle” sounds with very high, pure pitch

The fifth Alarm pattern technique involves whistles, i.e. high-pitched, pure tones with concentrated acoustic energy in upper frequencies. Whistle sounds are rare in nature and difficult to produce. They typically require special techniques and instruments and can only be sustained for short periods.

In chills-inducing passages, the most reliable ways we see artists pull off this technique are:

• Whistle register in lead vocals: very high pitch in lead vocals above the falsetto register, typically from female pop singers and coloratura classical sopranos

• High notes on fipple flutes: tin whistles, recorders, Native American flutes, piccolo, bagpipes, and other wind instruments with a whistle mouthpiece

• Air and steam whistle samples: recordings of alarms and whistles, used sparingly (at most twice in one song) during a certain climax or solo section, typically in the latter parts of songs