Birdsong sounds like the most natural sleep sound there is. Many "nature sounds for sleep" mixes include it. We recorded a dawn chorus and measured it the same way we measure every recording before it becomes an 8-hour track. It failed every test, and the numbers explain why.
The recording
A two-minute dawn recording, made outdoors at first light. We compared it with Mountain Brook, the steadiest water recording in our library, using the same analysis.
| Measure | Dawn birdsong | Mountain Brook | What it means |
|---|---|---|---|
| Loudness variation | 3.73 dB | 0.31 dB | Birdsong swings 12 times more |
| Spread (P95–P5) | 12.83 dB | 1.04 dB | Quiet gaps, then loud calls |
| Loud events | 42 per min | none | A new sound every 1.4 seconds |
| Tone centre | 2217–4238 Hz | 1115–1136 Hz | Pitch keeps jumping |
| Recording level | −59.5 dBFS RMS | normal | Needs about +35 dB of gain |
Loudness variation is the standard deviation of the level in 400 ms windows. A loud event is a moment more than 6 dB above the median level.
Why it keeps you awake
Birds sing in short, bright calls. In our recording there were 85 of them in two minutes. Each call is a small change in the sound, and the ear notices change. A steady sound fades into the background after a few minutes. A sound that changes every second and a half never does.
The pitch makes it worse. The centre of the sound moved between about 2,200 and 4,200 Hz, which is the range our hearing is most sensitive to. A brook sits lower and holds still.
For tinnitus masking the problem doubles. Between the calls there are quiet gaps, and in those gaps the ringing comes straight back. A good masking sound has no gaps at all.
The hidden problem: noise
Birds are small and usually far from the microphone. Our recording peaked at −38.5 dBFS, so it needed roughly 35 dB of gain to reach a normal listening level. Gain lifts everything, including the hiss of the recorder and the low rumble of distant traffic, which made up about 8% of the energy between 100 and 300 Hz. Over a full night, that background becomes part of what you hear.
When birdsong does make sense
Birdsong is a good daytime sound. It feels alive and it pulls your attention outward, which helps for a walk, a morning routine or a short break. Those same qualities are what make it a poor choice for the hours when you want your attention to switch off.
What to use instead
Choose a sound that stays even: a steady stream, a river, or a soft hiss. Our measured picks are in the tinnitus masking guide.