This article expresses the author's opinion at the time of writing. There are no guarantees of correctness, originality or current relevance. Copying the whole article is forbidden. Transcription of selected parts is allowed provided that author and this source are mentioned.
The Web Morse player and subsidiary pages (Koch trainer, Morse Hero) got an "improvement": background noise. Strange as it seems, it sounds more natural and even easier to pay attention to (at least for me), perhaps because it helps to mask the real-world noise. Another minor improvement is the addition of some second harmonics. This gives some tone color to the beeps.
Currently, the Morse beeps are generated by a) pre-generating sound buffers with dots and dashes, and b) play these buffers at scheduled moments. This approach is very efficient, but not very flexible. Introducing other distortions like tone/volume oscillation, faint CW signals from other stations, etc. will demand real-time Morse generation. If time allows, I intend to do this move in the next few days.