Sound Pressure Sensor

Working with a Sound Pressure Level sensor works as described in the general article on how to use sensors. In this article, we assume you have successfully initialized the devices with the Tinkerforge Device Manager, and you stored all connected devices on a global variable devices. We also declared a global variable called sound.

Next, we need to know the device identifier, which 290:

// Get the sound pressure level sensor via its device identifer
sound = devices.getDeviceByIdentifier(290);

Once we have a reference to the sensor, we can register a callback function:

// We want to be informed when a new sensor value arrives
sound.registerListener(soundChanged);

Of course, we have to actually define the function:

function soundChanged(val) {
   // Do something with the value object
}

Reading the sound pressure level

Instead of just one single value, the sensor delivers four different values:

1. Sound level in decibel

2. Spectrum length

3. Spectrum chunk offset

4. Spectrum chunk data

We can access the array of value via the val object:

function soundChanged(val) {

    // Get the decibel value
    var decibelValue = val.getValue("decibel_value");
    
    // Check if this actually was decibel event, if not we get -1 as result
    if(decibelValue !== -1 && decibelValue.type === "decibel_value") {
        log("Decibel: " + decibelValue.value)
    }
}