Chirrup · Cricket thermometer

Hear the temperature. Crickets chirp faster when it's warm. Hold your phone toward one for about 15 seconds and Chirrup turns its rhythm into the air temperature.

How it works

The microphone signal is split into frequencies. Chirrup finds the cricket's pitch (usually 2.5–5 kHz, well above traffic and voices), follows how loud it is, and measures how regularly it repeats. A reading counts as Steady once the rhythm has held for a moment. Then Dolbear's law from 1897 turns the chirps per minute (N) into a temperature:

• °C = 10 + (N − 40) / 7
• °F = 50 + (N − 40) / 4

Dolbear measured the snowy tree cricket. Other species, including the field crickets common in Europe, chirp at their own rates, so expect an error of a few degrees. It works between about 10 °C and 30 °C, and only for crickets that chirp in a regular rhythm.

A whole chorus works too: crickets in one place share the same temperature, so together they still repeat at one rate.

Questions

How can a cricket tell the temperature?

Crickets are cold-blooded, so the muscles they chirp with work faster when it's warm. The chirp rate rises steadily with temperature. In 1897 the physicist Amos Dolbear turned this into a formula, known as Dolbear's law.

How accurate is it?

For the snowy tree cricket, the species Dolbear measured, expect to be within a few degrees between about 10 °C and 30 °C. Other species chirp at their own rates, so readings can be further off. Save readings next to a real thermometer to see how close it is for your crickets.

Which crickets work?

Crickets that chirp in a regular rhythm, from a single cricket to a whole chorus. Insects that buzz in one continuous trill, like many bush crickets, have no rhythm to count and give no reading.

Is my audio recorded or uploaded?

No. The sound is analyzed on your device as it comes in and is never saved or sent anywhere.

Does it work offline?

Yes. Install Chirrup to your home screen and it works without a connection, which helps out in the fields at night.

Audio is analyzed on your device and never uploaded. Once installed, Chirrup works without a connection.

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