Some advertisements for language training material (like this and this) have a dubious claim that each language has its own frequency range of sounds, or a "pass band", so that listening to sound, including music, tuned to that range (don't ask me how) and getting your brain used to the range beforehand will improve your acquisition of the language.
The claim seems to originate from the work French ENT doctor Alfred Tomatis published in the 1950s, and apparently it's originally applied to treatment of children with disabilities rather than language learning.
As far as I can tell this is pseudoscience, or at best protoscience, but all I've been able to find are some papers, typically in developmental psychology, saying they failed to replicate the claimed benefits but not dismissing it out of hand (e.g. Kershner et al. 1990). This website boasts a list of studies that purportedly demonstrate the effect of the method, some of which are from well-known academic publishers. I wonder if they do in fact demonstrate it and how representative they are of the literature available (and if they meet the ethical standards on conflicts of interest).
Is there an outline or review of the method from a linguistic point of view? Like one that I can point to in order to deter someone from falling for it.