- #1

idmena

- 14

- 0

Hi! I need some help understanding something related to sound.

I am currently studying a book called

Later on he continues to talk about transmission loss at a partition. In that case he considers a thin wall, and takes into account the mass, the spring constant and the damping coefficient. In that case he doesn't even consider the characteristic impedance of the material that the wall is made of, and that equation does depend on the frecuency of the incident signal. He explained that when the incoming frecuency is much bigger than the resonant frecuency of the wall that's when the well known mass law applies, and continues to consider the other cases.

So tell me, how is this possible? When an acoustic waves enters a different medium all of it's components are reflected by the same factor? If so, how comes the transmission loss depends on the frecuency? The transmission loss is defined in terms of the transmission coeficient, which he stated before that depends only on the characteristic impedance of the media.

Attached are two pictures with the equations I mentioned. Sorry I don't know latex.

Thanks in advance

I am currently studying a book called

*Sound Propagation. An Impedance Based Approach*, by Yang-Hann Kim. There is a part where he talks about reflection and transmission of acoustic waves on a flat surface of discontinuity. He gets the coefficients for presure and velocity, and them combines them to get the power reflection and transmission, that is the one that would affect what we can hear. But I find it odd that his equations do not depend on frecuency, only in the characteristic impedance of the two media. In other words. The reflecion and transmission of power do not depend of the frecuency of the wave, all the components of the incoming signal are reflected and transmited by the same factor.Later on he continues to talk about transmission loss at a partition. In that case he considers a thin wall, and takes into account the mass, the spring constant and the damping coefficient. In that case he doesn't even consider the characteristic impedance of the material that the wall is made of, and that equation does depend on the frecuency of the incident signal. He explained that when the incoming frecuency is much bigger than the resonant frecuency of the wall that's when the well known mass law applies, and continues to consider the other cases.

So tell me, how is this possible? When an acoustic waves enters a different medium all of it's components are reflected by the same factor? If so, how comes the transmission loss depends on the frecuency? The transmission loss is defined in terms of the transmission coeficient, which he stated before that depends only on the characteristic impedance of the media.

Attached are two pictures with the equations I mentioned. Sorry I don't know latex.

Thanks in advance