What listeners everywhere hear in a lullaby
In a study published in Current Biology in 2018, 750 people in 60 countries heard 14-second excerpts of songs recorded in 86 mostly small-scale societies, among them hunter-gatherers, herders and farmers, and judged what each song was for. Without knowing the language or the culture, they told lullabies apart. In a second experiment, listeners rating the same excerpts heard the lullabies as simpler in melody and rhythm, slower, with a less steady beat and lower energy than dance, healing or love songs.
That list is a brief. Each trait has a phrase that asks for it:
| What listeners hear | What to write |
|---|---|
| A slower tempo | “slow, 65 BPM”. A number is the most direct request; leave it out and the pace is the engine's choice |
| A simpler melody | “a simple, gentle melody that repeats” |
| A simpler rhythm, a softer beat | “no drums”, or “a soft sway, no percussion” |
| Lower energy | “a hushed, close, almost whispered vocal” |
| Few sounds at once | one or two instruments: “music box and soft piano”, “a single nylon-string guitar” |
A keepsake, or a song to fall asleep to
A lullaby can be one of two things, and they want different lengths. One is a keepsake: a song with a name in it, made to be played for someone and kept, where two or three minutes is plenty. The other is a sleep song, which has to last while a baby settles and should have very little happening in it.
Decide which one you are making, because they want different briefs. A keepsake wants the name, two or three true details and a voice. A sleep song wants length and very little happening: turn on Instrumental if words would keep a toddler listening, and on Pro ask for a length rather than hoping for one. Every generation returns two takes, so a sleep song can simply be the two of them played back to back.
Your own words, and the name
Many lullabies start from words a parent already has, in whatever language the family sings in. Paste them in Custom mode laid out as they should be sung, and write out the lines you want repeated: a lullaby lives on repetition, and the words are sung exactly as they appear.
For the name, write it in the brief or in the words. If it is spelled differently from how it sounds, add the sound in the brief (“Siobhan, pronounced Shi-vawn”), because the engine sings the spelling. In a birthday song the name comes back again and again; in a lullaby once per chorus is usually enough, so say how often you want it.
At bedtime: quiet, and out of the crib
The safe-sleep guidance from the US National Institutes of Health is to keep the baby's sleep area empty except for a fitted sheet: no soft objects, no toys, no other items. A phone or speaker playing the lullaby belongs on a shelf across the room, not beside the pillow.
Volume matters as well. When researchers measured 14 infant sleep machines at full volume, every one was louder than 50 decibels at 30 centimetres, the limit recommended for infants in hospital nurseries, and three went past 85 decibels, a level that over eight hours risks hearing damage even in adults. The same caution applies to a phone: keep it low, keep it at a distance, and use a timer rather than playing it all night.
Before you press Create
- Keepsake or sleep song: decide first
- A tempo as a number, around 60 to 70 BPM
- One soft voice, one or two instruments, no drums
- The name spelled the way it sounds, and how often to sing it
- Your own words in Custom mode, with the repeats written out
- At bedtime: low volume, across the room, on a timer
Sources
- Mehr et al., “Form and function in human song”, Current Biology, 2018 — PubMed Central
- Hugh et al., “Infant sleep machines and hazardous sound pressure levels”, Pediatrics, 2014 — PubMed
- Ways to reduce baby's risk: keep the sleep area empty — Safe to Sleep, US National Institutes of Health
- Lullaby — Wikipedia
Written and fact-checked by the Tunely team · Updated