beep command seems to be generating tone of incorrect frequency

[Foss User <fossist@gmail.com>]

I was using the beep command in the 'beep' package to generate tones.
I find that it doesn't quite  behave as expected. I ran the following
two commands:

$ beep -f 440 -l 1000
$ beep -f 880 -l 1000

The 880 Hz sound sounded lower in pitch than 440 Hz sound.

Also,  it sounds out of tune with the sound generated by the following commands:

$ ecasound -i tone,sine,440,1 -o alsa
$ ecasound -i tone,sine,840,1 -o alsa

Note that the output of this command sounds proper, i.e. 880 Hz sounds
higher in pitch than 440 Hz. Is this a bug in the beep command?