Low pass filter not working

Hello everyone,
I am trying to make a passive low pass filter for a speaker. I have some .15mH coils. I put two of them in series and tested it on my inductor tester and it reads 303:mu: H. Which is .303 mH correct? So i put that in series with an 8hm: speaker, hooked up my signal generator and mt scope to the speaker. The problem is i don't see any change in amplitude whatsoever all the way up past 10kHz. I figure it should drop of at 4kHz. Any ideas as to what could be going wrong?

Try replacing the speaker with a 8 ohm resistor. I think the filter will work.

I attached an impedance graph of a low frequency speaker. (4 ohm) The impedance changes with frequency. In your case the 8 ohms could be 2x, 3x or more at 10khz. At the point where you think you 300uH (.3mh) coil is interacting with 8 ohms, the speaker impedance is really 20 ohms. The impedance of the coil and the impedance of the speaker are headed up with increased frequency.

i just tried it with a resitor and it still does the same

Can your signal generator drive an 8 ohm speaker properly? I doubt it.
You need to drive them with a circuit that has a very low output impedance like a power amplifier.

ok, i'll try with an amp and see what happens

you were correct AG. i couldn't turn it up loud enough to really see how much it dropped because my kid is sleeping and it sounds like a spaceship landing when i sweep the frequency : ) and i don't want ti give him nightmares