The Alarm pattern is a set of auditory cues that humans and animals use to communicate fear. Screams, shrieks, and sirens all have distinct, consistent acoustics (see the five methods below). The more abruptly you introduce the Alarm pattern into your music, and the more you intensify the aural properties that distinguish it, the more likely audiences are to experience frisson. 

Note: The five techniques below are not mutually exclusive and tend to occur in pairs.

The Alarm pattern can trigger our fight-or-flight response by directly activating the amygdala, a brain region that helps us respond to threats.

It’s theorized that our evolutionary ancestors stumbled upon and started using alarm cues because they aided survival in three ways. First, these hard-to-ignore sounds alerted nearby listeners that a threat was nearby, helping our kin avoid danger. Second, these sounds induced fear in nearby listeners, preparing our kin to physically respond to danger (either by fleeing or coming to the aid of the person raising the alarm). Third, these sounds communicated to the source of the threat that we had spotted them, helping to raise the perceived costs of (and hopefully deter) an attack.

To ensure an honest signal and avoid the boy-who-cried-wolf problem, we use highly atypical sounds to indicate alarm. One unusual feature of alarm sounds is that they concentrate energy in the 3-4 kHz range . This mirrors the resonant cavity of our ear drum; we are most sensitive to this precise part of the audio spectrum. Sounds in this range as especially piercing. For example, opera singers use a squillo technique that brings out a “singers formant” around 2.8-3.2 kHz. This allows singers to project over an orchestra, but is also likely why some people say opera singing sounds like screaming. A second unusual feature of alarm sounds is their rapid amplitude modulation. While normal speech modulates at a rate of 4-5 Hz/sec, screams modulate at 30-150 Hz/sec. Recent research confirms that alarm cues are so specific that we can reliably distinguish them from similar cues denoting aggression or other forms of heightened arousal.

Our listener data indicates that high-pitch sounds with unusual frequency features called non-linearities (chaotic broadband energy, sidebands, and warbles, all between and outside the normal harmonics of a voice or instrument) often induce frisson. You know non-linearities when you hear them; these are harsh, “noisy”, hard-to-ignore sounds. Non-linearities are a central component of alarm calls in nature. Given that it takes significant energy to strain a sound system and produce spectral non-linearities, our brain generally trusts that they are an honest signal of fear and danger.

In chills-inducing passages, some of the most reliable techniques we see composers and performers using to achieve this method include:

• Overblown sound sources, especially atonal vocal screams and screeching strings
• Heavy distortion, especially on electric guitars and other electronic instruments
• Certain timbres that produce inharmonic noise, especially waterphone, metallic percussion (gongs, cymbals, anvil, chimes, etc.), and even guitar-amplified feedback

Distortion isn’t a “hack” that automatically gives listeners chills. Our data suggests that when using this technique, it helps to:

• Placement: Place these sounds at the end of a cadence or climax of a phrase when listeners are distracted by the melodic movement
• Context: Minimize orchestration to make the sound as conspicuous as possible
• Follow-Up: Sustain these sounds to re-assure listeners they are intentional, and then re-start the melodic flow to create space for a positive listener appraisal response

Anecdote: Biologist Daniel Blumstein, an expert on animal alarm signals, collaborated with film composers to study the effect of boosting non-linearities to film soundtracks. Blumstein not only found that film soundtracks already heavily incorporated non-linearities, but that enhancing non-linearities further increased and intensified audience emotional response.

Our listener data indicates that rapid, repeated shifts between very close or very distant notes often induce frisson. This technique is a variant of Technique #2 above; it creates a moderate, more exaggerated type of acoustic roughness with a modulation rate that is still radically higher than that of the average musical sound. The result is an unstable, piercing, strobe light-like effect.

In chills-inducing passages, some of the most reliable ways we see composers and performers using this technique method include:

• Tonal screams by talented lead vocalists
• Certain instrumental techniques like trills, flutter tongue on winds, and tremolo string bowing, or certain instruments like the ratchet
• Staggered filters applied to electronic sounds and vocal techniques like ululation

Trills aren’t a “hack” that automatically gives listeners chills. Our data suggests that when using this technique, it helps to:

Our listener data indicates that high-pitch sounds with unusually rapid, non-linear amplitude variations referred to as acoustic roughness (a measure of how rapidly a sound’s loudness fluctuates that we perceive as beating or rattling) often induce frisson. Roughness is like a strobe light effect for sound, producing a pulsing effect that can vary in rate and height. This method is effective for frisson because rapid, non-linear amplitude modulation is a key component of human and animal alarm calls. We already heavily associate it with fear; it’s the distinguishing characteristic of screams and alarm clocks. Given that high-roughness sounds are unusual and difficult to produce, they are highly attention-grabbing.

In chills-inducing passages, some of the most reliable ways we see composers and performers use this technique include:

• Narrow dissonant harmonic intervals (e.g. minor seconds) whose tones are close enough in frequency to interfere and create a pronounced rattling
• Clashing sound sources, or when multiple instruments combine to sound dissonant chords, often doubled and with added reverb to create a very unstable sound
• Steady state sound sources such as singing voice, bowed strings, brass, and wind instruments, which result in more salient roughness than impulse sources like percussion and plucked strings (although the ratchet is an effective instrument for this technique)

Screams are not “hacks” that automatically give listeners chills. Our data suggests that when using this technique, it helps to:

• Placement: Place dissonances at moments when listeners are distracted (e.g. at the end of a cadence, on the upbeat, etc. to make them as jarring as possible
• Context: Continue the consonant, melodic flow over the top of the dissonances so that they are not overly disruptive for listeners
• Follow-Up: Sustain or repeat the dissonant intervals, and leave a rest after, to re-assure listeners they are intentional and create space for a positive listener appraisal response

Our listener data indicates that siren-like acoustics – rough sounds with a gliding, arcing pitch contour and pronounced peak – often induce frisson. This method is likely effective for two reasons. First, arced pitch contours paired with acoustic roughness produce significant non-linearities. Researchers have recently found that arced pitch contours are one of the key defining characteristics of effective screams. Second, arced pitch contours trigger learned associations with alarm due to our repeated exposure to ambulances, storm alerts, and other sirens. Together, this makes siren-like sounds highly effective for frisson.

In chills-inducing passages, some of the most reliable ways we see composers and performers using this technique include:

• Single, slow arced sounds that glide up and down over several seconds (asymmetric)
• Rapid, repeated arced sounds, typically one or more per second
• Recordings of real-life sirens (e.g. ambulances, storm alarms, etc.)

Sirens are not a “hack” that automatically give listeners chills. Our data suggests that when using this technique, it helps to:

• Placement: Introduce siren sounds on instruments that differ dramatically from the preceding timbre palette of a song to make them as jarring as possible
• Context: Use reduced texture and increased dynamics to focus listeners on the sound of the siren and prevent non-acoustic distractions
• Follow-Up: Prolong or repeat the siren to re-assure listeners it is intentional and create space for a positive listener appraisal response

Anecdote: The trailer for the film Star Wars: Rogue One is a frequent submission to our dataset of listener frisson moments. The video features a prominent, repeated siren throughout the final 30 seconds of the trailer. Sure enough, the top comment on the Youtube video, with 1500 upvotes, is: “That siren is bone-chilling”.

Our listener data indicates that very high pitch with acoustic energy concentrated in upper frequencies often induces frisson. This method is likely effective because it is difficult to fake; very high-pitched sounds are an honest signal of alarm in nature, and require special techniques and instruments to achieve in music.  

In chills-inducing passages, some of the most reliable ways we see composers and performers using this technique include:

• Whistle register in lead vocals, especially with female vocalists and coloratura sopranos
• High notes on “bright” instruments that bring out upper frequencies, especially trumpet squeals, electric guitar, tin whistle, and crotales
• High notes on reed instruments, especially piccolo, clarinet, and bagpipes

Whistles aren’t “hacks” that automatically give listeners chills. Our data suggests that when using this technique, it helps to:

• Placement: Place these notes at the beginning of a section or end of a cadence to make them as conspicuous as possible for listeners
• Context: Precede leaps with subtle, rubato slow-downs or pauses and change the texture or rhythm after the leap to make it as jarring as possible for listeners
• Follow-Up: Hold the high note to create space for a positive listener appraisal response