You may have heard that the sound of the bass drone contains the chanter notes C and E (as well as low and high A). This demonstration will help you hear these pitches. First, listen to the plain bass drone sound. I got the original sound from David Daye's page, snipped out a bit, analyzed and resynthesized it.
The frequency of the chanter's C (when correctly tuned) is exactly 5 times that of the bass drone, so if we could listen only to every 5th harmonic of the bass we should hear a C. I removed the other harmonics from the original sound and amplified it 8 times, so we can hear the C by itself.
To help you hear the C in the drone sound I created a sound in which the C-harmonics are turned off and on repeatedly. This lets your auditory system pick them out of the original drone sound. The sound consists of:
The C-in-the-drone should stand out clearly at the end.
The frequency of the chanter's E (when correctly tuned) is exactly 6 times that of the bass drone, so if we could listen only to every 6th harmonic of the bass we should hear an E. Just like before, I removed the other harmonics from the original sound, leaving the E by itself.
And here's the E-in-the-drone sound. I find the E much more difficult to hear than the C.