Ultrasonic and Sound pressure

[wizard]

Hi,

I have a question According to Ultrasonic sensors.
When I was looking the web for an Ultrasonic sensor for ranging, I noticed that those sensors have a parameter called 'sound pressure level':
**broken link removed**

I know what are the pressure level and decibel for an audible sound, but I am not able to see what it does mean for an ultrasonic sensor or an ultrasound wave? I made a search but GOOGLE was not helpful for that!

Can someone clear me and tell me what's that and how to understand it?
besides can somebody tell me how they measure that parameter for their sensors?

I know that decibel is a scale and there must be a reference for it but I don't know how to construe it for an ultrasonic wave??

Thanks for any guidance

 

[stevez]

Sound is the result of pressure variations or fluctuations - the physics is the same, more or less for low, high or ultrahigh frequencies. Propagation, absorption, attentuation are all quite dependent on frequency but it would seem that the units of measure are the same.

As you are aware the decibel level depends on a point of reference. You'd need to know what point of reference is used for the sensors you are considering. It's possible that there is an understood industry standard that is used - so everyone in that industry assumes a reference point without actually stating it.

There's lots of good information available but much of it in the form of books - protected by copyright (unfortunately for us). You might google on "sound pressure level" and "sound power level" - you might be fortunate enough to find discussions that will help. Looking thru a physics book or two at a local library might help get you going too.

 

[wizard]

Thanks Steve,

I have 2 books:
"Fundamentals of acoustics" by "Kinsler" and "Fundamentals of physics" by "David halliday".
So I know what SPL means for an audible sound. Here it is:
SPL=(10dB)log I/I.
which I. is a referenced point(Threshold of human hearing) and it is 10^-12W/m^2 .
Is there any referenced point for those Ultrasonic sensors too? If so, what's that?
Unfortunately Google could not help me when I searched for 'Ultrasonic sound pressure level".

Even as I know dB meters are working at a certain frequency(8kHz if a remember correctly). So the frequency tends to be an important factor for measuring SPL.
Is there any dB meter for ultrasonic waves too?

 

[wizard]

It seems no any expert took a look at my question here, or maybe my question is a BAD one?!