Definition

The Alarm pattern is a set of auditory cues that humans and animals use to communicate fear. Screams, shrieks, sirens, squeals, and yelps all share a set of distinct acoustic features. These features are difficult to produce, which helps alarm cues serve as honest signals of danger (avoiding 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 technique involves high-pitch sounds with frequency features called non-linearities. Non-linearities are distortions produced when a resonator is strained beyond its upper or lower range. They include sidebands, warbles, and broadband energy outside the normal harmonics of a sound source. You know non-linearities when you hear them; these are “noisy”, strained sounds that often induce frisson.

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

• Distortion from straining a voice or instrument above its natural range: atonal screams by talented lead vocalists (producing significant “noise” or broadband energy), “screeching” high-pitch violins, overblown reed instruments like clarinets and piccolos, and “squeals” from overblowing brass instruments

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. Whether listeners experience frisson depends on the preceding context and the onset, intensity, and variation of the non-linearities. 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: High pitch with rapid amplitude modulation 

The second Alarm technique involves high-pitch sounds with a frequency feature called acoustic “roughness”. Roughness is like a strobe light effect for sound. Rough sounds have unusually high amplitude modulation rates, or fluctuations in loudness (30-150 Hz vs. 4 Hz for normal speech), that perceive as beating or rattling (think of the buzzing of an alarm clock). At high frequencies, rough sounds often give listeners chills.

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

• Single tones staggered to produce roughness: tonal screams in lead vocals, electronic tremolo effects applied to electric guitar, organ, or pads, flutter tongue on wind and brass instruments, tremolo bowing on string instruments, and certain percussion instruments like the ratchet 

• Two dissonant tones sounded simultaneously to produce roughness: minors second, tritones, and major sevenths, usually sounded in the same octave as held chords or rapid trills, and embellished with doubling and reverb, so that the tones interfere with each other and produce a pronounced “beating” effect

• Many impulse sound sources struck unevenly at high pitch: most frequently plucked high notes across a violin section, where the players don’t coordinate when they sound each note, resulting in an overall irregular, staggered sound that produces acoustic roughness

Technique #3: Certain arcing pitch contours (“sirens”)

The third Alarm technique involves certain gliding notes with a rise-and-fall contour. These sounds have a pronounced peak, making them highly attention-grabbing. Recent research has confirmed that arced contours are in fact a key way listeners distinguish real vs. fake screams. Artificial alarm sounds like ambulance sirens purposefully copy these pitch contours, as do musicians, making them especially effective for frisson.

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

• Fast, higher sirens: moving from medium to high pitch, with fast-attack entrances, loud dynamics, non-linear acceleration into the peak, and where the majority of the acoustic energy is concentrated in the peak rather than during the rise or fall (think faster police sirens as opposed to slower air raid sirens)

• Slow, lower sirens: moving from low to medium pitch, with legato entrances, muted dynamics, a linear rise and fall, and where the majority of the acoustic energy spent in the rise and fall rather than the peak itself (think slower air raid sirens as opposed to faster police sirens)

• Vocals or voice-like electronic sounds: given that this technique mimics human and animal alarm calls, the most reliable timbre for pulling it off is human voice, followed by certain pads and samples of real-life sirens that effectively mimic and accentuate the voice-like features of these sounds

Technique #4: Whistles and whistle register

The fourth Alarm technique involves sounds with very high, pure pitch with concentrated acoustic energy in upper frequencies. Whistle-like sounds are rare in nature and difficult to produce. They typically require special techniques or artificial whistles, require significant energy to produce, and can only be sustained for short periods. So when we hear them, they are highly attention-grabbing and often frisson-inducing.

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

• Whistle register: the vocal register that lies above falsetto and that only certain talented female pop singers and coloratura classical sopranos are able to reach, typically sounded during quiet, low-energy passages when the contrast of the sudden whistle note will be as jarring as possible for listeners

• High notes on fipple flutes: tin whistles, recorders, Native American flutes, and other wind instruments with similar constricted mouthpiece, typically sounded with moderate dynamics to avoid overblowing the instrument and creating too shrill of a sound

• Samples of air and steam whistles: recordings of blown whistles and whistle-like alarm sounds, used sparingly (typically in the latter parts of songs) to add intensity to a climax or end of a well-signaled cadence when listeners are distracted by the melodic and harmonic movement

Technique #5: Certain upward, concentrated frequency shifts

The fifth Alarm technique involves upward, concentrated frequency shifts. The resonant cavity of the human ear drum is 1-4kHz and especially 2.8-3.5kHz. Unanticipated high notes with concentrated resonance in these frequencies are especially piercing and attention-grabbing. The louder and more concentrated the attack of these note, the more likely listeners are to experience frisson.

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

• Squillo: where opera singers accentuate a formant right around 3,000 Hz to achieve an especially bright, piercing sound that can project over the orchestra, typically achieved on notes that have high – but not too high – fundamental frequency given that singers tend to lose their formants at the top of their range

• High notes on certain timbres like bag-pipes and trumpets: that can sounds with a similar resonance to squillo and achieve a similarly bright, piercing sound; usually embellished with holds at the peak of a melodic line or climax to draw listener attention to the frequency content of the sound

• Embellishment with large leaps, orchestration, and dynamics: these upward frequency shifts are typically set up by an octave leap or a similarly large interval after a relatively quiet, sparse section, all to make the contrast of the high-pitch entrance as prominent and jarring as possible for listeners