The test proposed by the article solves some of these problems by requiring generation, and by using distraction after the short target tone is produced. The point is to move on from the target tone faster than consultation with hidden external references can take place. If recognition is not immediate, then one must first hold the note in short-term memory, then after the distraction, compare it to internal reference pitches from tonal memory. This is not accurate since short-term tonal memory itself is not stable, being influenced by distraction. So for some small number of tones (could be all of the chromatic scale), HTM could do well, depending on the person, but maybe performance is not even…, and HTM should never be able to match lesser-heard (e.g. non-standard) pitches well… However, if recognition is by APE, then any tone can be immediately recognized into an abstract form and as something distinct, and easily matched later in the abstract forms.

Under this regime, it would seem that most people who recognize and generate tones upon request probably just have varying degrees of HTM and have developed a quick lookup table as internal reference, which would seem to be malleable by training as with other kinds of memory (for people with good associative memory anyway). APE, however, probably cannot be learned — it’s a kind of idiot savant skill like people who know large number multiplications in one second — it just cannot be done with a lookup table.

My best guess is, these sounds may recall the vocalization of some kind of open-range nocturnal predator of humankind’s ancestor, something one is innately equipped to recognize and fear.