We’ve once written a plug-in with different background noises. Add Noise.ny
Put it in your plug-in folder and restart Audacity.
It appears in the effect menu. This means that it only works with existing tracks and does not generate a new one. Set the mix to 100 %.
You can thicken the noise by applying it a second time (with mix 50 %).
You can also apply a hard-limiter effect to make the sound more aggressive (limit at about -12 dB and re-amplification afterwards).
A low-pass filter softens the sound, if necessary (roll-off 6 dB, 1000 Hz or higher).
You can make it more convincing by first creating the noise for only 0.7693 s (for 78 Rpm) and repeat this selection for the desired length you need (repeat effect).
Over this pattern you can add multiple times the crackling noise–especially at the beginning, where it is very (white) noisy.
Hope that helps.
Thanks, I’m playing around with the crackle and white noise settings to try and get it just right. Is there anyway it could be added as an option to the add noise plug-in under “Type of noise”? I guess I could just experiment with the existing settings and then save the result, but it would be a nice feature to have.