some day ago i went to buy a dB meter(sound level meter) to measure the intensity of my ULTRASONIC transducers at 40kHz.
i noticed dB meters can only measure soundlevels at a specific range,
in the data sheet of ultrasonic transducers we can see the MAX of intensity of transducer, so there must be a device to measure its intensity?
does anyone know what that device is really?
some day ago i went to buy a dB meter(sound level meter) to measure the intensity of my ULTRASONIC transducers at 40kHz.
i noticed dB meters can only measure soundlevels at a specific range,
in the data sheet of ultrasonic transducers we can see the MAX of intensity of transducer, so there must be a device to measure its intensity?
does anyone know what that device is really?
A dB isn't an absolute value, it's just a ratio, so it has to be compared to something else - so it's not really that useful. If you are trying to measure dB's acoustically (or any other type of sound measurement) you need a microphone that's either flat over the range in use, or who's response is accurately known and can be compensated for. How many microphones have you seen with a flat response to over 40KHz?.
A dB isn't an absolute value, it's just a ratio, so it has to be compared to something else - so it's not really that useful. If you are trying to measure dB's acoustically (or any other type of sound measurement) you need a microphone that's either flat over the range in use, or who's response is accurately known and can be compensated for. How many microphones have you seen with a flat response to over 40KHz?.
Most things are really measured against something, but they are real values, you know what a WATT is, and you can easily measure and calculate it because it's an absolute value. A dB isn't an absolute value, so it's pointless saying something is 80dB - you have to says it's 80dB relative to something else. You also have the confusion of voltage dB and power dB, which are very different!.
A lecturer at tech many years ago told us "people who use dB's in conversation don't know what they are talking about" - although it's perhaps a little harsh?, it's generally pretty true as well!.
Loudspeakers reproduce frequencies within the bandwidth of sound level meters so have their sensitivity rated for a number of Db's at a certain input and at a certain distance. Ultra-sound transducer manufacturers must have some kind of level meter to measure their products, but I doubt if you could find one.