The historic bells of the Munich Frauenkirche were checked. – Munich

This week Michael Plitzner, 47, was at the top of the towers of the Munich Frauenkirche. There he and a colleague examined the ten large bells. The ringing of the cathedral could therefore be heard in the city center for hours. Plitzner is a mechanical engineer and theologian, he has a doctorate in foundry technology. The expert from the European Competence Center for Bells ECC-ProBell had with him measuring devices, a computer, a block and tackle and an extendable ladder.

SZ: Mr. Plitzner, does the examination in the cathedral affect you?

Michael Plitzner: Absolutely. About 80 percent of my work as an engineer takes place at my desk, so when you can climb a church tower again, it’s always a lot of fun. I’m also a researcher and I learn something new every time we go out.

I actually meant, do your ears ring when you stand so close to ringing bells for hours?

Oh I see. No, we usually work with noise protection on the ears. These large bells can produce between 120 and 130 decibels. It’s as loud as standing next to a plane taking off. But your question is perfectly valid. I sometimes meet older bell experts or craftsmen who have to be spoken to quite loudly. I think it’s a man’s thing not to always protect himself well.

But you seem to take care of your hearing, do you need a particularly good one for your work?

I don’t have perfect pitch, which would be nice, but it’s not absolutely necessary. For me, the focus is more on how a bell sounds when it rings, it is not so important whether, for example, individual partial tones are not completely clean and I can recognize that. For me, the dynamic sound is crucial, i.e. the balance between high and low tones.

You always learn something new, what for example in the Munich Cathedral?

A lot of little things. Working on the large salve bell, the Susanna, was particularly exciting and beautiful for me. It has a diameter of a good two meters, weighs between six and a half and seven tons and dates from 1490. We tested the ringing angle on it. It is one of the largest church bells in Bavaria, it is as if a truck is swinging back and forth. A difference in the ringing angle of just one or two degrees has a big impact…

Ringing angle means how high a bell swings?

Exactly. About 50 degrees is a good angle for a nice bang-bang effect. We tried to reduce the angle a bit so that the clapper hits a little less hard to protect the bell as much as possible. But then the attack became irregular. Ultimately, she was already very well adjusted.

They kept ringing all ten bells, the seven in the south tower and the three in the north tower. What exactly did you do with it?

Two measurements. On the one hand sound recordings when the bells are rung via the electrical system. We checked whether they hit rhythmically and regularly, for example, we can readjust the rhythm of the ringing beat. We also struck the bells by hand to capture their sound at rest. These sound recordings allow us to capture the so-called musical fingerprint to describe the condition of the bell.

What can you find out?

Bells are unique handicrafts and always slightly out of round. If this rotational symmetry is not given, then the tones split up. This is audible through beats. You hear them, for example, when you swing your finger towards a wine glass, it’s these irregular tones, this swelling and fading. This is a physical effect. Glasses aren’t perfectly round either. Based on the measurements, we can judge when the splitting of the tones becomes critical. We can clearly judge whether the bell has a dent, a break or even a crack.

You were already in the cathedral in 2017 for a survey, so you can use the comparison to analyze the changes.

We don’t actually need a reference at all. It is an ingeniously simple digital analysis method in which the individual frequencies are separated and each individual tone is considered. Already in the next few days we will know better how the bells are doing.

What’s your first impression?

You still have to wait. However, I did not notice any noticeable beats or critical tone splits in the tones, so that no significant changes since 2017 can be assumed.

And how was the ringing?

There are always some small tonal improvements. But actually everything works very well in the cathedral. The bells are serviced by a company every year, and the diocese is exemplary.

Have the weather extremes no impact?

During the extensive renovation of the tower, the bells and the yokes, i.e. the suspensions, had already been taken into account. In other church towers, pigeon droppings often clog the bells, or extreme dryness causes loose connections. There is none of that here, which is to be expected from this venerable building. The special thing about our churches is that the bells are hung up so that they can be moved, but that is a constant load on the bells and the church towers.

Not a few people feel disturbed by the ringing of bells today. Could the discomfort also be due to the sound?

The sound is actually a very important aspect. There is a research project at the musicological institute of the University of Vienna, with which we cooperate, which examines both the quality of the bell sound and the volume. In fact, it is not always the latter that is perceived as disturbing.

Can the sound be significantly improved?

The design of a clapper is very important for the sound. The size, the ball on the clapper, the weight distribution. There are some striking differences. A lot can be compensated for by changing the clapper. The ringing of the church bells shapes our sense of home, one should not underestimate that.

So it’s a lot of habit how to feel this ringing?

This can already be perceived as the sound of the city, especially in places that have this cultural imprint particularly strongly. We see this as confirmation of our work to protect the bell as a cultural asset, even if the churches are becoming less and less important. I think that today the church congregations are almost too hasty in turning off the hourly chime when complaints come. For other people who are not bothered by this, there is only silence. They miss their bell telling them the time.

The oldest bells in the Frauenkirche date from the 14th century. What could be wrong with pieces that old?

With such old bells you can always see where the clapper has struck over the centuries. I always hope that the dents on the brass knuckles have not worn out too much. Edges of many bells are damaged, for example when they were removed during wartime. These are typical signs of an old bell. It’s amazing how well the cathedral bells are preserved here. You can continue ringing with a clear conscience. If they are rung wisely and gently, they are cast for eternity.

How can these bronze giants be repaired?

If a bell has a crack or large chips, then you have to remove it from the tower. There are a few companies that can weld bells. The presence bell in the cathedral had to be welded once, which is now forever a weak point that you have to watch out for.

You first studied theology and then mechanical engineering. How do you feel when you climb up church towers?

I enter a church as a theologian and as an engineer. It’s nice to come into such a big place of worship like the Frauenkirche. The encounters with the people there are something special. But I often find the silence in a small village church to be very intense and special, and I really enjoy such moments.

Michael Plitzner is a mechanical engineer and theologian – the ideal combination for his job

As a specialist, what do you say about the ringing of the Munich Cathedral, how do you feel about it?

You can hear the Middle Ages here. If I close my eyes, I can take myself back to the 14th century, that’s contemporary history. Ulrich von Rosen’s presence bell is from 1492, when Columbus discovered America. The thought sends shivers down my spine. What is great, however, is this mixed ring of bells from different eras: bells from the Middle Ages, from the Baroque period and three modern pieces, the most recent ones are from 2003. They fit in very well and expand on what is already there. Mixing old and new is well balanced. Great if it goes well together.

There are people who swear by singing bowl therapy for their well-being. The way you describe your experience, the sound of bells also has an effect on the human body.

I don’t think it’s necessarily physical. But mentally, the sounds certainly resonate with some people. This can be positive if it is combined with a nice experience like Christmas or a wedding. Of course, church bells can also trigger negative feelings when they remind you of something not so nice, when the death knell rings or the memory of a requiem comes up.

And how does the sound of bells affect you?

There are these two hearts in my chest. The engineer hears the ringing of the bells and the intensity of the clapper. As a theologian, the sound of the bells is very enriching for me. Then I hear the voice of God calling to prayer.