Nominal or Hum
bill at NxrBwf-ldcqcV4vs-_9c1UMpLKt47ZRsuvvrgUJfNnudJkqR6BG6w7xtk8ptHWS-vdtBrDJdqGecFgTv8bM.yahoo.invalid
Tue Apr 15 11:10:42 BST 2008
>Just out of interest, at what diameter do you swap from nominal to
One of the experiments in my PhD thesis deals specifically with this
point. The experiment was done on 17 test subjects, all musically
competent, at a range of nominal frequencies between 315Hz and
4,000Hz. There is no clear breakpoint, but rather a gradual
transition from one mode of listening to another. There is a neat
graph showing the results but I'm not able to post it from work. As
well as pitching by the hum, prime or nominal, for big bells we have
the secondary strike effect (pitching by partial I-7, the first rim
partial above the octave nominal, sounding about a 4th above the
primary strike). The results were as follows:
315Hz nominal: 2/3 hear secondary strike, 1/3 pitch from nominal
397Hz nominal: about 50/50 secondary strike / nominal
Nominals from 500Hz to 1260Hz: most peple pitch by the nominal
1587Hz nominal: 50/50 between nominal and prime
2000Hz nominal: 2/3 prime, 1/3 nominal
2520Hz nominal: 3/4 prime, 1/4 hum
3175Hz nominal: 50/50 between prime and hum
4000Hz nominal: 3/4 hum, 1/4 prime.
For pitches arising from secondary strike and nominal, the effect is
independant of the loudness of the partials. For pitching by prime
and hum, the louder partial wins, other things being equal. Results
are potentially different for every listener, because the pitches
heard are generated in the individual's auditory system.
These results also help explain why small old-style bells sound
worse than large old-style bells; in small bells, the various
pitches compete and sound discordant. In true-harmonic bells, all
the pitches are the same 'note'.
This is all explained in my thesis, of course . . .
PS there is a recording on 'Called Home' of a peal of small bells, I
forget where, where for my ears an octave jump upwards occurs half-
way round the circle. In rounds, I hear the back bells an octave
higher than the small bells.
More information about the Bell-historians