Question

Sound voice and helium

I understand that when you got standing waves set up, only certain frequencies are allowed and those depend upon the velocity and length of the air column.. but when we talk are we producing standing waves within us??.. i don't understand why when we stuff ourselves with helium, our frequency goes uP?.. cause in general the frequency of a progressive wave is always independent of the medium and only depends on the source itself right?

Answer 1

hey come on glee answer : :O :O

Answer 2

velocity also depends on the composition of the media in this case a gas.\[v _{gas}= v _{air} \sqrt{\frac{ M _{air} }{M _{gas} }}\] for Helium M= 4 for air M=29 so sound is 2.7 time faster in helium compared to air.

Answer 3

yea.. but according to v = f(lamda) .. as velocity changes lambda changes to make sure frequency remains the same!!!..

Answer 4

We are talking about the production of a sound, it's mechanics. Take a pipe organ. The standing waves wavelength depend on the length of the pipe. The velocity depends on the molecular mass. The frequency is then set. The actual production of sound is a vibrational phenomena, a movement of gas, if the gas is less dense it is more easily displaced.

Answer 5

so since stationary waves are set up inside our voice column we get the difference??.. but then again.. once the waves spread out.. they are normal progressive waves right?

Answer 6

oh wait.. so you mean.. the stationary waves are first set up.. and then its THAT frequency which travels out as a progressive wave?.. so that makes sense :D thank you!

Answer 7

so . if the entire room were filled with helium.. but somehow i was wearing some suit and i was breathing normal air.. then when i spoke.. people would hear me normally right???

Answer 8

people who are exposed to helium environment i mean!