I was intrigued to hear some
of the bell sounds offered by "electronic carillon" manufacturers, and
thought it would be interesting to investigate why they sound so
different to real bells. Easy enough to do in principle - download
the sound of an e-bell and compare it to the sound of a real one.
Nothing's ever that straightforward of course, but even the difficulties
one runs into are worth recounting.
The electronic carillon I
chose to examine is one manufactured and marketed by Schulmerich Bells,
of Sellersville, PA, USA. And the particular voice is titled
English Bells. You can hear the sample I used on their website,
rendering the beautiful Coventry Carol (Lullay, lullay, Thou little tiny
child), a piece so wondrous as to deserve its own
Here it is played by Schulmerich's
Extracting a note to test
rapidly becomes a choice of one. Only the first note is suitable,
as every other note contains remaining vestiges of the notes before it.
Bb it is. And since the second note kicks in at 0.7 seconds later,
we have just 700mSec of sound to play with!
The real bell
Since the Schulmerich e-bell
was described as an English bell, it's logical to compare it to a real
bell from that country. Conveniently, I had a recording I'd made
of the bells at the National Carillon, Canberra Australia. The
bells there are by Taylor Bells in Loughborough, England, so fit the
bill perfectly. The wind was high on the day I recorded the bells,
so there is some background noise. But at least I have the full
bell strike and decay to play with.
Compare the sounds
I've edited together this
comparison of the sounds. Firstly, you'll hear three strikes on
the Taylor's bell at Canberra, followed by its decay, and then three
strikes from the Schlumerich e-bell. I had to fiddle with the end
of the recording. Because I only had 0.7 seconds of useful sample,
the recording would have stopped dramatically but disconcertingly after
the third strike. I did the only decent thing I could think of -
add a fourth strike and fade it rapidly, to disguise the abrupt
Quite a dramatic difference in tonal qualities, I think
you'll agree. That should mean our analytical processes should
also have little difficulty in identifying the obvious differences.
Unfortunately, one of my favourite analytical tools,
WaveAnal's Partials Decay section, refused to have anything to do with
the Schulmerich sounds, probably because it quite reasonably regarded
700mSec as not enough to work with.
It's a shame I didn't have access to the full decay of
the e-bell as I suspect Decay Analysis would have an interesting story
to tell there too. The partials of real bells attack and decay at
different points in the strike, so the tone develops as it progresses.
I'm not hearing that in the Schulmerich emulation, but, without a longer
decay, it would be difficult to confirm analytically.
WaveAnal's automatic Partial Identification system was
also struggling, for reasons we will see in a moment. But it was
able to process and export the FFT data in a form I could deal with,
leaving me to struggle with the identifications!
I ran both sounds through the system and used Excel to
prepare the comparison below:
As you can see, the results
are very different!
The real bell, Canberra Bb,
is shown in pink. (I've dashed it so as not to conceal any
overlaps with the e-bell in blue.) You can see only four partials,
the Hum at just under 1000Hz, the Prime the small blip just under
2000Hz, the Tierce at about 2200 and the Nominal at about 3750.
The e-bell is represented by
7 partials. You'll see only one of them is at the same frequency
as the real bell's, and that is the Hum just under 1000Hz. There are
also two partials below the Hum (decidedly abnormal!), and the other
partials are at very high levels compared to the real bell's.
In musical terms, please!
Enough of this geeky Hertz
stuff, and tell us in musical terms, I hear you grumble. This
table might help...
Tierce, minor third
The first two columns give the names of the usual partials,
and the pitch we would expect them to be at.
The third column
gives the pitches of the four partials we detected from the Canberra
bell sound, and their deviations. All as expected and within a
remarkable 5 cents. Note the absence of the Quint. It may
well become more prominent at Forte playing levels.
fourth column gives the Schulmerich e-bell results. As we saw in
the graph above, only the Hum partial seems to be where we would expect.
But note that the other pitches we expect (Db and F in the case of a Bb
bell) are represented, although not where we expect. The Db's are
below the Hum (unheard of?), and the F is just above it, rather than in
its expected position an octave higher.
Legitimate in a certain sense. If a bell note is
really a chord, then this is an inverted chord.
But wait, there's more!
But we have a bit more to explain. Schulmerich's
nearest candidate for a Prime is a B, not a Bb; its Quint is an E, not
an F, and its Nominal an Ab, not a Bb. To make that all a bit
clearer, I've added a fifth column which computes the deviation (in
cents) of each partial from where we might have expected it.
Remembering that 100 cents is a semitone, some of those deviations are
My guess is that the e-bell sound is synthesised, and is
not a real bell sampled. Once you decide to synthesise, you are
freed from the constraints of the real world, and can put your partials
anywhere you like, and make them the size you feel works best. So
this is a construct arrived at in cold blood.
I imagine the decision to lower the pitch of the Db and
F partials was in the aim of giving the bell greater gravitas. I
can't put forward a reason for the large deviations, excepting to remind
us all that bell pitch is largely a psycho-acoustic construct, not a
simple matter of physics, and it might be that extensive listening tests
confirmed these parameters as the most pleasing.
Capable or Culpable?
Carillonists are commonly scathing about electronic
carillons - their endearing descriptor "bongatron" is enough to confirm
that. Whether the analysis and comparison above adds fuel to that
derision is in the eye (and ear) of the derider. I imagine
Schulmerich went to a lot of trouble in designing that sound, and, as
presumably it sells, they must regard it as successful. They could
probably defuse some of the discontent if they did not attempt to pass
the sound off as something it quite clearly isn't - the sound of an
English Carillon. It isn't even the sound of a bell.
should add that the choice of company and sample used in this article is
by chance only. Further, that this comparison cannot be extended
to other voices by that company or other companies.