Singing Bowls

Author: Anup Poudyal
Publisher: The Middle Way Publications
Edition: Authorised Machine Accessible Edition
Section: Chapter 7
Chapter Title: Using Tuners, HRV and EEG
Copyright: © 2026 Anup Poudyal. All rights reserved.

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Chapter 7
Using Tuners, HRV and EEG

Some of you might have seen me pull out my phone, measure the exact frequency of a bowl, and then say something like, “This is a heart chakra bowl” or “This one matches the throat chakra.” Well, here is what is actually going on. Once you get the hang of using a tuner, the rest of the journey into frequencies, chords, consonance, dissonance, and even those famous 432 hertz debates start to make a lot more sense.

And after reading this chapter, I hope that if you ever hear a know-it-all, spiritually awakened guru say something like, “My bowls are so spiritually aligned that when the monk does his chanting on the stage, these bowls start singing too,” you’ll be able to nod and say (without rolling your eyes), “Yes, that’s actually very possible. If the resonant frequency of your bowl matches the frequency of the monk’s chanting, then by the principle of sympathetic resonance, your bowl might sing as well.” Although, to be honest, I wouldn’t mind if you did roll your eyes. In fact, I’d probably give you a high five.

For as long as singing bowls have existed, people have relied on their ears and their hearts to connect with the sound. Long before anyone spoke of Hertz (Hz), frequencies, or calibration systems, bowls were simply played, and their value was judged by how they made you feel. We are starting to lose this today in the endless noise and debate about numbers. Despite all the technical detail in this book, particularly in this chapter, my intention is to bring the focus back to what matters most: the listening, the feeling, and the truth of sound itself.

Today, we have tools that let us explore sound in new ways. One of the simplest is the chromatic tuner, a small device or phone app that listens to an instrument and tells you the note it is producing.

This may feel overly technical, especially if you came to singing bowls to escape the constant buzz of technology. Yet many people find it surprisingly satisfying. I remember the first time I showed a group how a tuner works. As the bowl began to sing and a little letter and number appeared on the screen, one woman laughed softly and said, “Ohhh, the technology!” Everyone leaned forward, fascinated. It was as though the tuner had translated the invisible beauty of the sound into something visible and measurable.

A Companion, Not a Replacement

Here is the vital thing to remember: a tuner is not a replacement for your ears or your intuition. It does not tell you whether a bowl is right for you, nor can it measure how the vibration feels in your chest or how your mind softens when you hear it. What it offers is a companion, a way to explore, to learn, and sometimes to confirm what you are already experiencing. If you usually avoid apps or gadgets, do not worry. You do not need to become “technical” to enjoy this. Think of the tuner as a curious friend: it listens with you, points out details, and helps you notice what you might otherwise miss. The real magic, however, remains in your direct experience with the bowl itself.

Getting Started: Downloading a Tuner App

If you have never used a tuner before, here is how to begin:

1. Open your smartphone’s app store.
2. Search for a chromatic tuner.
3. Choose an app with good reviews; most free versions work well, while paid apps may offer extra features.
4. Download the app as you would any other.

That is it, you now have a portable tuner in your pocket.

What to Expect When Testing

Open the app, play your bowl, and hold the tuner nearby. You will usually see two things:

• A letter (the musical note)
• A number (the frequency in Hertz)

A few things to know:

• Shifting numbers are normal. Singing bowls are natural instruments, and their vibrations naturally change as the sound fades.
• You may notice multiple readings at once. At times, the tuner briefly registers a higher octave instead of the main tone. This reflects the richness of the sound rather than a fault.
• Background noise can affect readings. Nearby conversation, movement, or street traffic may confuse the tuner and cause fluctuations.
• Notes do not need to be exact. A bowl described as “C” may sit somewhere between C and C sharp. That variation is part of its character and charm.

Common Questions and Experiences

Over the years, I have learned that using a tuner with a singing bowl often sparks as much curiosity as the bowl itself. Some people already know what a chromatic tuner is and may have even used one before. But even for them, there is still a spark of fascination when they see me, someone who speaks about meditation, mindfulness, and ancient traditions, suddenly pull out a smartphone and check the exact frequency of a bowl.

It is a moment where worlds meet: the deep roots of a centuries-old practice meet the glow of a modern screen. For many, it is unexpected, and that is part of the joy.

For most people, however, the tuner is entirely new. They lean in with wide eyes, tap their friends on the shoulder, and say, “Look, look what he’s doing!” This fascination does not seem to be about age, culture, race, or gender. I have seen teenagers, retirees, and everyone in between captivated by that little display of letters and numbers. In those moments, technology is not distracting us from an ancient art; it is connecting us to it.

Why Does the Reading Keep Changing?

One of the first questions people ask, sometimes with a hint of worry, is, “Why does it keep moving?” The answer is simple: singing bowls produce complex layers of sound called harmonics. Unlike a single-pitch tuning fork or an electronic beep, a bowl’s sound is alive and dynamic. As it vibrates, different overtones rise and fade, and the tuner does its best to keep up. Far from being a flaw, this shifting is a sign of richness. It means your bowl is giving you not just one note, but an entire landscape of tones to explore.

Different Apps, Different Results

Another common question is, “Why does my friend’s tuner say something different to yours?” The reason is that each tuner app uses its own software to interpret the sound, and environmental factors also play a role. Background chatter, wind, or a distant bus rumbling past can all nudge the reading in different directions.

This is why I often recommend keeping two tuner apps on your phone if you are testing bowls regularly. If one gives an odd reading, you can cross-check. It is a simple step that reassures people they are seeing a fair reflection of their bowl’s voice.

Two different apps might also show different notes for the same bowl because each tuner app can be set to a different calibration. For example, one phone set to A4 = 440 Hz might show a G note reading, whilst another set to A4 = 432 Hz might show an F♯ reading. The bowl has not changed; it is the tuner’s reference point that makes the difference.

Changing the Calibration

Calibration is just the starting point your tuner uses to measure all the notes, a bit like agreeing on the length of a ruler. Some people are used to rulers marked in centimetres (like the standard 30-centimetre school ruler), while others use rulers marked in inches (such as the familiar 12-inch version). In the same way, temperature can be measured in Celsius (where water freezes at 0 °C) or in Fahrenheit (where the same point is marked as 32 °F). Neither system is wrong; they are just different ways of agreeing on a reference point. In ancient times, people measured length by the cubit (the distance from elbow to fingertip) or by using everyday objects like grains or stones. Likewise, your tuner is usually calibrated so that A4, the A above middle C on a piano, is set to 440 Hz. This means the tuner measures every other note in relation to A4 at 440 Hz. You can change this reference to 432 Hz, or even something quite different, such as 415 Hz, but the principle remains the same. Calibration is simply about choosing the “ruler” your tuner uses to measure sound.

To change the calibration, open the tuner’s settings and adjust the A4 reference point. While it is set to 440 Hz by default, you can change it to 432 Hz so the tuner uses it as its new reference point.

This becomes important when you plan to use several bowls together, whether to create a musical piece, perform, or offer a sound bath. If each bowl is checked with a tuner set to a different calibration, they will not harmonise properly with one another. By keeping the calibration the same across all your bowls, you ensure they share a common reference point, allowing their tones to blend smoothly and supporting the atmosphere you are trying to create.

One crucial point to understand is that most metallic singing bowls are not tuned like modern instruments. The people who make these bowls are skilled craftsmen, not musicians. Their focus is on the shape’s symmetry, the evenness of the walls, and the bowl’s structural integrity. They ensure there are no hidden fractures, that the rim is smooth, and that any tiny holes are filled so that the bowl can sustain its sound for a long time.

If you come across a metallic bowl labelled with a note such as A or F, do not assume it was tuned to that pitch; it almost certainly was not. What makers or sellers actually do is test hundreds of bowls and then label them according to the notes they naturally produce. Testing and labelling are very different from tuning. The only true way to tune a metallic bowl is to carefully and evenly reduce its wall thickness, which lowers the pitch. Minor adjustments, like slightly heating the bowl or adding a small amount of water, can also shift the pitch, but these changes are temporary and not very significant.

It may seem contradictory that, on the one hand, each metallic bowl is unique and not deliberately tuned, and, on the other hand, when you buy several bowls for a performance or sound bath, they need to harmonise well. The key is to see these as two complementary approaches: every bowl will always carry its own natural voice, but by testing them with the same calibration and labelling system, you can select bowls that complement one another. In this way, their individuality is preserved while their combined soundscape remains balanced and coherent.

By contrast, crystal bowls are usually machine-made and often marketed as being tuned to specific notes. As a result, they can be more consistent when tested with a tuner. However, even crystal bowls can vary slightly; two bowls labelled “C” may not measure the same when checked to the decimal place. This does not make one better or worse than the other; it simply reflects the natural variation in how sound is produced. With metallic bowls, the beauty often lies in their complexity and layered overtones, while crystal bowls are appreciated for their clarity and precision.

Exploring Frequencies with a Generator App

From time to time, you may hear people talk about “special frequencies” like 432 Hz or 528 Hz. Some suggest these numbers hold unique healing powers, while others believe sound is experienced more through its overall texture than through single tones. If the healing quality were truly hidden in exact numbers, then listening to pure electronic tones at those frequencies should feel the most calming. But in practice, they do not. Pure frequencies without natural harmonics or subtle variations can sound flat, robotic, and even unpleasant over time. This is where much of the debate lies: is there something unique about specific numbers, or is it the way we experience those sounds as a whole?

To explore this question, it helps to experiment. We have already used a tuner to measure what note a bowl is producing, but there is another simple tool you can use: a Frequency Generator App. You can download one for free on your phone. Instead of listening to your bowl, the app plays tones for any number you type. This means you can hear for yourself precisely what 432 Hz or 528 Hz sounds like, rather than just reading about it online.

Not too long ago, these kinds of tools were only found in laboratories or in the hands of musicians working with early electronic instruments, and they cost thousands of dollars. Today, the same ability fits into your pocket, ready for you to explore at no cost.

For those who enjoy experimenting, I encourage you to watch demonstrations of the famous Chladni plate experiment. Simply search online for “Cymatics: Chladni Plate, Sound, Vibration and Sand.” In these demonstrations, sand scattered on a flat metal plate rapidly organises itself into intricate geometric patterns as the plate vibrates at different frequencies.

What makes this experiment so striking is how quickly these changes occur. Within seconds, sound visibly reshapes matter. Witnessing this provides a powerful foundation for understanding the deeper principles we will explore later, and it is well worth the time. It deepens your understanding of how vibration interacts with physical matter, and ultimately, how sound might shape and influence something as complex and alive as the human body.

Fig. 7.1 Chladni plate experiment

If you want to try a simple version at home, you can use a flat, rigid metal sheet securely supported above a speaker so that the vibrations can transfer to the sheet. Sprinkle a thin, even layer of dry sand across the surface and play a steady tone through your frequency generator app. Watch closely as the vibrations take hold: specific frequencies will instantly ripple the sand into recognisable geometric patterns, while others may produce only scattered movement. You may also notice that the results vary depending on the plate’s size, thickness, or shape.

You can also try another experiment using water to see these patterns in motion. Begin by pouring a thin layer of water, about one to two millimetres deep, into a flat, shallow dish or tray away from the speaker to avoid accidentally spilling water onto the electronics. Once prepared, carefully place the dish securely on top of the speaker. Open your frequency generator app and play a steady tone through the speaker. Watch closely as the water reacts to the vibration.

The results will depend on the size of the dish and the amount of water you use. A larger surface might show slower, broader movements, while a smaller one often creates quicker, tighter ripples. Similarly, water depth affects the complexity of the patterns. High-frequency waves on a shallow layer of water can form delicate, mandala-like shapes that snap into place instantly, while lower-frequency waves in deeper water tend to scatter ripples more randomly.

Fig. 7.2 Ripple tank experiment

These experiments also help put the frequency debate into perspective. The patterns do not appear because one frequency is universally “special,” but because the sound happens to match the dimensions and material of the plate or the volume of water. Change the setup, and the “special” frequency changes too. Be warned, this is “geek land.” It takes stability, patience, and a willingness to experiment. And remember, none of this is necessary to enjoy your bowl; it is simply a playful way to see how vibration interacts with the physical world.

This is the heart of the practice: moving from second-hand claims to first-hand discovery. Sound stops being an abstract idea and becomes something you can see, feel, and explore directly.

Find Your Own Hearing Range

The textbook says we should be able to hear from 20 Hz to 20,000 Hz. In reality, every person’s ears are different. With this app, you can slide down and see how low you can go, then push it up and find where the sound just disappears. Most adults are surprised when they realise that the upper limit of their hearing is often around 14,000 to 15,000 hertz. That is just life, though; age, noise exposure, and genetics all play a role.

It is a simple little test, but it proves a significant point: sound is personal. What feels sharp or soothing to one person might not even be audible to another. And after knowing all this, and even trying some of these experiments yourself, you will likely find that trying to convince someone else which frequency is ‘soothing’ or ‘healing’ feels pointless, because everyone perceives and experiences sound in their own unique way.

The Guru Joke (Round Two)

Remember our friend, the guru, who claims his bowls start singing on their own when monks chant? Well, now you have the app to test that. First, measure the bowl’s note with a tuner. Then play that exact frequency back through the app. If the bowl begins to resonate, the truth is clear: bowls do not distinguish between a monk, a criminal, or, in this case, a smartphone.

Testing the Famous Numbers: 528, 432, and 440 Hz

People often come to my stall and ask about these “special” frequencies. My answer is usually, “OK, let’s play them and see how long you can actually handle it.” Spoiler alert: most people find the mid-range frequencies (around 150–250 Hz) far more soothing than the big internet favourites like 528 Hz. It is not that 528 or 432 are meaningless; they do sound distinct. But once you have tested them side by side, you realise your body tells you the truth faster than any online article ever will.

Beyond Hearing: Feeling the Vibration

Here is where it gets interesting. Drop the slider down below 40 Hz, and you will notice you might not “hear” the sound anymore; you feel it. It is that low rumble in your chest, the same reason big deep bowls feel like they are wrapping around your whole body. This is a great experiment that shows sound is not just for your ears. It gets into your skin, your bones, your entire nervous system.

Bowls vs. Pure Tones

Now compare a clean sine wave from the app with the note of your bowl. Play your bowl first, then play the same frequency through the app. Now compare the two. The difference is night and day. The app produces a clean sine wave, a sterile “beeeep.” The bowl, by contrast, gives you a living, breathing sound full of layers, harmonics, and subtle shifts.

That comparison alone is worth the download; it shows you why bowls feel alive in a way pure electronics never do. It shows that in nature, sound is always complex, full of layers and harmonies.

Glass-Shattering Fun

If you really want to push your experiment, try the classic wine glass trick. Every glass has its own resonant frequency. If you can hit it and hold it long enough, the glass will vibrate like crazy, even shatter. You probably will not get there with a phone speaker, but with a proper sound system, you might. Even just watching the glass tremble is enough to see resonance in action.

It is the same principle often invoked to explain how the walls of Jericho might have fallen in the ancient story, and why sound has long occupied a place between faith and science. Across cultures and centuries, people have sensed that vibration is not merely something we hear, but something that acts, influences, and reshapes the world around us. This intuition continues today in the hope that sound might one day be harnessed to affect the body at the cellular level, perhaps even in the treatment of serious illness. We will explore these possibilities more carefully in the next chapter.

Bringing It Together

So, what is the point of all this? A frequency generator app turns abstract numbers into real experiences. You find out your own hearing limits. You prove resonance in a way you can see and feel. You discover why bowls sound richer than machines. And you have got a couple of cheeky comebacks ready for when people throw 528 Hz at you.

Most importantly, you take sound out of theory and put it back where it belongs: in your own hands, ears, and body. That is the best way to learn.

Sound Waves vs. Electromagnetic Waves

Now that you know how to test the frequency of any sound with a tuner, and even play back any audible frequency using a Frequency Generator app, you can also tackle one of the biggest confusions in the sound healing world: the difference between sound waves and electromagnetic waves.

On paper, both seem similar because they are both measured in Hertz (Hz). But Hertz is simply a unit of measurement, like kilograms or pounds for weight. A stone and an apple may both weigh “100 grams,” yet their properties are entirely different. In the same way, a 7.8 Hz electromagnetic field in the Earth’s atmosphere (the Schumann resonance) is nothing like a 7.8 Hz sound wave. One is a field moving through space without requiring air; the other is a vibration travelling through a medium such as air, water, or your body.

This distinction is important. If someone asks, “Does your bowl play at the Schumann resonance?” The honest answer is no, that resonance belongs to the electromagnetic world, not the acoustic one. And even if I used a frequency-generator app to “play” Schumann frequencies, you would not hear them anyway; they fall well below the human hearing range. The lowest we can usually hear is about 20 Hz, while Schumann resonances sit closer to 7–8 Hz and under. That is why bowls cannot reproduce them, though it can still be a fun conversation starter.

That usually makes things click. Instead of blending science and myth into confusion, you bring the conversation back to experience. And the most important point to leave them with is simple: my bowl produces a sound that calms me. It may not affect everyone the same way, but for me, it works.

Advanced Experiments: Body and Brain

Now that you have seen how a tuner or a frequency-generator app can deepen your understanding of bowls, let us take a step further. Most people have never even heard of the following tools in relation to playing a singing bowl, and they certainly are not required for playing bowls. But for those of you who enjoy exploring the edges of what sound and vibration can do, there are two technologies worth mentioning: heart-rate variability (HRV) monitors and electroencephalogram (EEG) headbands. I personally use a Polar H10 chest strap for HRV, which costs me about AUD $129, and a Muse S headband for EEG, which costs around AUD $399. For advanced interpretation of the raw data, I use an AI assistant.

They sit outside the tradition of sound healing and are not used in everyday bowl practice. Still, they offer a unique window into what is happening in your body and brain when you play or listen. Think of them as optional “advanced experiments”, interesting if you love data, but never a substitute for direct experience.

Heart Rate Variability (HRV) and Singing Bowls

To measure the effect of sound on your body while you are playing a singing bowl, one of the simplest and most effective tools is an HRV (Heart Rate Variability) monitor. HRV refers to the minor, natural variations in the time between each heartbeat. Rather than aiming for a perfectly steady rhythm, a healthy heart shows subtle changes from beat to beat, and this flexibility is a strong marker of overall resilience and well-being.

Modern HRV devices, such as chest straps, wrist sensors, or finger sensors, translate these patterns into simple graphs or scores. When you play a singing bowl and begin to relax, your HRV usually shifts upward, reflecting activation of the parasympathetic nervous system, your body’s “rest and digest” mode. For many people, this shift happens within just 2–5 minutes of steady playing. The longer you stay with the practice, the more stable the “good heart zone” becomes, and interestingly, the benefits often continue even after you have stopped playing. Over time, using HRV feedback lets you track your progress. You might notice that you drop into coherence (that balanced heart zone) more quickly than before, or that you can sustain it for more extended periods. The technology confirms what your body is already teaching you: sound and presence really do shift your internal state.

What is even more powerful is that this awareness does not stay confined to sound practice. Once you learn to notice your body during bowl playing, you will start seeing it in daily life. You will notice your breath while walking, the subtle rhythm of your heart while talking, or even a shift in sensation while sitting in traffic. Simply paying attention to these processes can guide you back into coherence. In this way, the bowls become a teacher, not just in sound, but in cultivating a deep connection with your own physiology.

EEG (Brainwave Monitoring) and Singing Bowls

Just as HRV lets you observe your heart’s rhythm, EEG (electroencephalography) provides a window into the electrical activity of your brain. Small, non-invasive sensors placed on the scalp measure the brain’s electrical oscillations, the “waves” that rise and fall with different states of consciousness. When using an EEG with singing bowls, the key is timing. If you record while striking or circling the bowl, the hand and muscle movements often create “artifacts”—false spikes that can appear as Delta activity. That is why it is best to play the bowl for 5 minutes, then sit quietly for at least 15 minutes to allow the brain’s natural patterns to show clearly.

During this quiet period after playing, many people notice increases in Theta waves (4–8 Hz), linked to deep relaxation, creativity, and meditative states, and Alpha waves (8–12 Hz), associated with calm alertness and reduced stress. Over months or years of consistent practice, some meditators also experience brief Gamma spikes (30–100 Hz). Gamma is connected to moments of integration and insight when the brain synchronises across different regions. Research in advanced meditation traditions suggests that gamma bursts may accompany experiences of clarity, compassion, or profound stillness.

The best way to record and interpret your sessions is with an app called “Mind Monitor”, which works with Muse EEG headbands. After each session, you can export the data and even feed it into an AI assistant to generate an easy-to-read summary. This way, you do not need to be a neuroscientist to notice your progress.

One necessary caution: do not get attached to the numbers. EEG is a tool, not a scorecard. Every session is new, and the patterns will naturally vary. Read the data, notice any trends, and then let it go. What matters most is not whether your Alpha rose by 10%, but whether you feel more balanced, present, and at peace in your daily life. Over time, EEG feedback can train your awareness much like the bowls themselves: to notice your own inner rhythms, witness your thoughts as they arise, and gradually cultivate a mind that rests in equilibrium.

Reflection Exercise

1. Open the Tuner: Launch your tuner app and have your singing bowl ready.

2. Strike and Observe: Gently strike the bowl and notice what the tuner displays.

3. Watch the Changes: See how the numbers shift as the sound fades, and whether the tuner picks up a higher octave.

4. Adjust the Calibration: Switch the app from 440 Hz to 432 Hz. Notice how the display changes, even though the sound of your bowl remains the same.

5. Playfully Match the Note: If you have a metal bowl, tap it lightly with the suede side of your mallet, then hum or sing to match its note. Afterwards, try reproducing that note without the bowl.