Duke,
Of course it is. I noted that waves could be classified into three types. My point was to indicate that the particles do not move from their equilibrium position, but vibrate about it.
That's close enough.
On the face of it, this seems like a reasonable statement, but please describe how we should do this.
We surely count all the molecules of air in contact with the diaphragm, since they are certainly disturbed. They in turn disturb their neighbours - do we count those? They have neighbours too. Where do we stop?
If we only count the molecules in contact with the diaphragm, is that the mass we seek? It surely would be lighter than the membrane.
Do we reason like this - we consider the maximum excursion of the diaphragm (this would be for the loudest possible volume at the lowest frequency the membrane can produce) and multiply this by the area of the membrane and come up with a volume. Now we consider the density of the air (depends on temperature and humidity) and thus we have a mass. Is this it?
But the speaker hardly ever plays at this volume or at that low frequency, so does the statement "the mass of the membrane is lighter than the air it moves" have to be qualified with volume and frequency specifications? This was not done.
The problem I see is that the phrase is colourful and exotic, but not reasonable. It's a turn of phrase, an advertising slogan. That I don't mind, as the world of hifi is filled with such slogans. But it's not truth.
Regards,
The example given above of the "wave" in the football stadium is actually a transverse (or shear) wave, with particle motion perpendicular to the direction of wave propagation.
Of course it is. I noted that waves could be classified into three types. My point was to indicate that the particles do not move from their equilibrium position, but vibrate about it.
Sound waves are pressure waves, and most importantly are set in motion by physical displacement of the air particles.
That's close enough.
The mass of the air displaced by the diaphragm movement can be calculated and compared to the mass of the diaphragm itself.
On the face of it, this seems like a reasonable statement, but please describe how we should do this.
We surely count all the molecules of air in contact with the diaphragm, since they are certainly disturbed. They in turn disturb their neighbours - do we count those? They have neighbours too. Where do we stop?
If we only count the molecules in contact with the diaphragm, is that the mass we seek? It surely would be lighter than the membrane.
Do we reason like this - we consider the maximum excursion of the diaphragm (this would be for the loudest possible volume at the lowest frequency the membrane can produce) and multiply this by the area of the membrane and come up with a volume. Now we consider the density of the air (depends on temperature and humidity) and thus we have a mass. Is this it?
But the speaker hardly ever plays at this volume or at that low frequency, so does the statement "the mass of the membrane is lighter than the air it moves" have to be qualified with volume and frequency specifications? This was not done.
The problem I see is that the phrase is colourful and exotic, but not reasonable. It's a turn of phrase, an advertising slogan. That I don't mind, as the world of hifi is filled with such slogans. But it's not truth.
Regards,