TG struggles or fails to detect anything below 18000 BPH

TG detects my Swiza clock and Timex watch without any trouble, they both run at 18000 BPH. But TG struggles to detect my portable alarm clock which runs at 14400 BPH, and completely fails to detect my Equity alarm clock which runs at 12000 BPH. All tests were done using my laptop's built-in microphone without any changes between tests. It picks up a fairly clean signal for being a laptop mic.

Video demonstration: https://www.youtube.com/watch?v=O1wFaMU1lsc

[xyzzy42]

I have fixed this in my fork. See this commit for the reason, xyzzy42@e1e4367