How Do Pressure and Standing Waves Change with Distance and Interaction?

[physics_06er]

Hi there

Could someone please help with these questions.

A helmholtz resonator has a resonant freq. of 100Hz. draw graphs showing how the pressure and displacement of the air in the neck vary with time. how would these be different at the position of a listener some distance away...

i can draw the graphs but I'm unsure of the part about the listener being some distance away...??

and the 2nd one is ...explain how a standing wave can be formed by traveling waves, and hence how the frequencies of standing waves on a stretched string are related to the speed at which waves travel along the string?

all i know is that waves would be traveling in opposite directions..canceliing out..? is this even right?...any help much appreciaited

Thanks
physics_06er

 

[berkeman]

-1- The resonator will have a partial standing wave in it (partial because some of the sound energy has to get out the open end to propagate to the listener.

-2- What is the equation for a traveling wave? What do you get if you combine a left-travelling wave and a right-travelling wave? Also, what is the relationship between the velocity of propagation of a wave on a string, in comparison to the tension of the string and the linear mass density of the string?