The newest firmware version adds support for a buzzer to be used as a ticker. If you're used to commercial (mobile) devices or ever heard a Geiger counter clicking, you'll feel instantly familiar with the sound. This way, the count rate can be translated into an audible tone with which you can easily (only roughly of course) assess your surroundings.

Just connect your (passive!) buzzer between one of the broken-out digital pins and ground and enable the ticker in software. By default, digital pin 9 is used for this job ("RX" pin header), which obviously means that you cannot use the hardware UART connection and the ticker simultaneously. This pin assignment can be changed from within the Arduino IDE sketch.

The default PWM frequency for the buzzer is 3 kHz, which you can also change in the sketch. The actual click duration per gamma pulse can be set in runtime via the "set ticker <integer>" serial command. The number will set the duration in milliseconds. I'm using just "1" here, it's more than enough for me. This also means that audio output will saturate at 1000 cps in the worst case.

I also added new metrics to the device info page: "power cycle count" and "power-on hours". These are pretty much self-explaining and log the number of device reboots as well as the running time of the device in hours. They are logged in another file inside the same file system as the settings and only update at the device start and after every full hour of runtime.

Have fun!