You first have to learn to hear overtones. With this program you can do that. Whoever learns it will change his entire listening experience. This is because completely new insights into the essence of sounds and realities are opened up.

Radio Feature by: Tanja Gronde. Broadcast from 09.05.2020 on BR Bayern 2 and BR Heimat.

More about the broadcast [BR Bayern2 and BR Heimat].

Minghao Xu’s 2009 film brings us close to the mystery of overtones, which seems to become the stranger the deeper you look into it. The film illuminates the phenomenon from the perspective of some of the greatest experts in the field of overtone singing, with some exciting and well-researched scientific and philosophical backgrounds. This documentary film portrays seven international musicians and tells the story of the director’s personal fascination with ‘overtone singing’ and the fractal geometry of sound. An amazing journey into a mysterious world of sound.


  • David Hykes
  • Wolfgang Saus
  • Christian Bollmann
  • Danny Wetzels
  • Hosoo & Transmongolia
  • Jill Purce
  • Mark van Tongeren

Director and producer: Minghao Xu
2009 Traumzeit publishing house, David Lindner

You can buy the DVD of the film with some extras in German/English here.

Minghao Xu about his film (quote from facebook):

My first production – a documentary about overtone singing – was published in 2010. Now after 10 years I am making it available for free on YouTube.

A big Thank You to Danny Wetzels who introduced me to overtone singing, who was and is a musical inspiration and a friend to me throughout the years.

Big Thank You to Wolfgang Saus who has a deep understanding of the human voice, who is brilliant in teaching how to hear and sing overtones and who supported me massively in creating this documentary.

Thank You to David Hykes who touched me as a singer as much as an inspirational being.

Thank You to Christian Bollmann, Hosoo Dangaa Khosbayar, Jill Purce and Mark van Tongeren – without your presence, knowledge, voice and contribution this project couldn’t have manifested. And Thank You to David Lindner for your help to publish this project through the Traumzeit Verlag.


The full ringing of Aachen Cathedral, recorded on Christmas Eve at midnight.
Nice to see in the spectrogram how some tones develop only after the beat. And not always the loudest ones are also the perceived ones.

Mary’s Bell: strike tone g°+8, 2075 mm diameter and 5,800 kg.
Charlemagne Bell: strike tone h°+7, 1628 mm diameter and 2700 kg.
Joh. evangelist: strike tone d’+8, 1367 mm diameter and 1650 kg.
Joh. Baptist: strike tone e’+7, 1367 mm diameter and 1150 kg.
Leopardus bell: strike tone fis’+3, 1078 mm diameter and 800 kg.
Stephanus bell: strike tone g’+8, 1027 mm diameter and 700 kg.
Petrus bell: strike tone a’+1, 894 mm diameter and 450 kg.
Simeon’s bell: strike tone h’+8, 793 mm diameter and 300 kg.

The Mary’s Bell was melted down by the Nazis and re-cast in 1958. The bell motif is formed by the Latin hymn Veni Creator Spiritus.

After many years, I finally succeeded in 2017 to get a largely trouble-free recording. I recorded it from Katschhof, the place between the cathedral and the town hall and this time recorded it with wind-protected hypercardioid microphones on a high stand behind two lonely Christmas market stalls, and one hour before I visited all the security people (who guard the empty Christmas market stalls), discussed the recording and – important! – I showed them a place from where they could watch me without disturbing the recording too much.

For years there were always disturbances, unfortunately also with the acoustically most beautiful 3D recordings with OKM original head microphones 2014. Sometimes it stormed, sometimes it rained, sometimes the police drove over the Katschhof, sometimes a blower blew into a plastic print, or security people asked questions, or someone poked loudly with high heels into the Christmas mass. In 2017, hypercardioid microphones with windscreens largely blanked out the sounds of space and the wind.

I moved away from Aachen in 2018 and am happy to have this recording in my box. It gives feelings of home. For me, the cathedral is the most impressive thing in Aachen.

Software: Overtone Analyzer,

“Silent Night, Holy Night”, the world’s most famous Christmas song, was sung for the first time on 24.12.1818, exactly 200 years ago. On Christmas Eve 1818 the Arnsdorf village school teacher and organist Franz Xaver Gruber (1787-1863) and the auxiliary priest Joseph Mohr (1792-1848) performed the Christmas carol for the first time in the Schifferkirche St. Nikola in Oberndorf near Salzburg, Austria. (Wikipedia)

For this version for overtone singing, the brilliant pianist Michael Reimann has improvised a piano movement on the electric piano. The notes for overtone singing are suitable for beginners. At one point, however, a small psychoacoustic trick is used, because one of the melody notes is not actually included in the overtone series. Who can find it?

Michael Reimann:
Video: Ljubljana Christmas Market filmed from the castle.

At the moment you can download the German version of the BBC documentation, e.g. with Mediathekview, from the ZDF Mediathek: 4th Episode, Wonders of Anatomy – Medical Record X – Borderline Cases of Science.
Note: Video and link currently only work from Germany.

Surgeon Gabriel Weston has spent many years studying the functioning of the human body. In the series «Incredible Medicine: Dr Weston’s Casebook» she presents people from all over the world with the most unusual bodies and abilities.

One of them is the unique body control required for overtone singing (from 10:40 min.). In November 2016, a film team from BBC Science Production, Emma Hatherley (production, direction) and Alexis Smith (camera), produced a film at the Institute of Music Medicine at the University Hospital of Freiburg with Prof. Bernhard Richter and Wolfgang Saus.

Live images from the magnetic resonance tomograph show the complex motion sequences in the mouth and throat that are involved in overtone singing. Interviews explain the scientific background of the phenomenon.

Pictures of the Making-of


→BBC Website

This hearing test (it takes only 3:20 minutes) opens your hearing to a second listening level that is perceived by only about 5% of the musicians: The perception of overtones. This ability is essential for learning overtone singing. And it is a prerequisite for the practical implementation of singing phonetic and choral phonetics.

At the university hospital Heidelberg Dr. Peter Schneider and his working group found in 2004 that people perceive sounds differently, according to which half of the brain processes the sound. They developed the Heidelberg hearing test to find out whether someone perceives fundamental tones or overtones in a sound. →Here you can take the Heidelberg test

My hearing test is different. It tests whether someone recognizes more vowels or overtones in a sound. In the second part, it teaches how to shift the threshold between vocal and overtone perception in favor of overtones.

Saus’s Hearing Test

Listen to the first sound sample in a relaxed way. I sing a series of meaningless syllables on a single note. If you recognize a classic melody in it, then congratulations, you have a pronounced overtone hearing and belong to the 5% of people who have this perception spontaneously.

Sound sample 1

If you can’t hear the tune, don’t worry. At the end of the hearing test you will hear the overtones.

In the following sound examples, I will extract more and more sound information from the voice, which is interpreted by the brain as part of speech. Next, I sing the syllables by changing only the 2nd vocal formant. I hold the first one in a lower position, motionless. The syllables then only contain /ʉ/ sounds, the melody becomes clearer for some now.

Sound sample 2

If the tune’s clear now, congratulations. Here the melody is heard by 20-30%. Maybe you just suspect the melody and don’t know if you’re just imagining it. Trust the imagination. Your hearing picks up the melody. Only a filter in your consciousness says that the information is not important. Speech recognition is much more important.

I want to reveal the melody at this point: it is “Ode to Joy” by Ludwig van Beethoven’s 9th Symphony. In the next example I whistle it tonelessly. Thus your brain will learn better what to listen to. Listen to sound sample 3 and then to sound sample 2 afterwards.

Sound sample 3

Does it work better? If not, listen to the next sample.

In sound sample 4 I leave out the consonants. Now the Broca Centre, the brain region for speech recognition, has nothing left to do and passes the hearing attention on to other regions.

Sound sample 4

Now about 60-80% hear the melody clearly. If you don’t hear the melody here, you are probably classified as a fundamental listener in the Heidelberg test. This has nothing to do with musicality. You are in the company of some of the best flutists, percussionists and pianists.

In the next example I completely alienate the sound. I lower the third formant by two octaves with a special tongue position until it has the same frequency as the second. This results in a double resonance, which does not occur in the German language.

Sound sample 5

The technique is called overtone singing. The ear now lacks information from the familiar voice sound, and individual partial tones become so loud due to the double resonance that the brain separates the sounds and communicates them to the consciousness as two separate tones.

You will probably hear a flute-like melody together with the voice now. Overtone singing is an acoustic illusion. Because in reality you hear more than 70 partials. Physical reality and perception seldom coincide.

In the last example I walk the whole way backwards to the beginning. Try to keep the focus on the melody all the time. Listen to sound sample 6 more often, it trains the overtone hearing and makes you feel safer in the perception of the sound details.

Sound sample 6

Our reality is created within ourselves. And it can be changed.

The Daxophon by Hans Reichel

Who does not remember to have made a ruler made sound by plucking at the edge of the table as a child. The German guitarist, improviser, composer and instrument inventor Hans Reichel (1949-2011) from Wuppertal has brought this simple principle to a professional level.

A 30 cm long wooden tongue is played with a cello bow. In a resonance box, the sound is picked up by contact microphones. The Daxophon Is an idiophone and at the same time a string instrument.

The Dax takes a decisive function. This is a handy, round shaped block with which the pitch is varied. On one side the block has frets so that sound sequences can be played, while the smooth side allows flowing glissandi.


What particularly fascinates me is the voice-like sound that the Daxophon produces. This comes through vocal-like formants, which arise when the Dax blocks the oscillation in the wood tongue at the contact points.

It can only say yes, no no.

Hans Reichel at a performance

Daxophone: Hans Reichel - Bubu And His Friends
Hans Reichel - Le Bal (excerpt)
Daxophone - Hans Reichel

At the bottom in the related links you’ll find a building instruction on the page (Flash) >downloads.

My colleague Anna-Maria Hefele made me aware of these charming instrument.

Related Links

Radium Audio Ltd: Official. 2013. Radiumphonic Inventing Sound Series #1 - Daxophone Dinosaurs. (zugegriffen: 12. März 2017).
soundsculpture. 2007. Daxophone - Hans Reichel. (zugegriffen: 12. März 2017).
Dez Tab. 2013. Hans Reichel - You Can Dance With Me. (zugegriffen: 12. März 2017).
shuffleboil. 2009. Hans Reichel, Ulrichsberg 6.12.09. (zugegriffen: 12. März 2017).
CH1PS. 2017. Hans Reichel - Yuxo. (zugegriffen: 12. März 2017).
GeninhaNinha. 2016. Hans Reichel Sometimes At Night. (zugegriffen: 12. März 2017).
artazamino. 2014. あざみ野コンテンポラリーvol.5 ハンス・ライヒェル×内橋和久 Listen to the Daxophone. (zugegriffen: 12. März 2017).
Shane Speal. 2016. How to Make a Simple DIY Daxophone (Hans Reichel instrument). (zugegriffen: 12. März 2017).
O A. 2016. Hans Reichel (Musiker). Wikipedia. 27. Dezember. (zugegriffen: 12. März 2017).
luvs7ruck. 2010. Hans Reichel - Street Song. (zugegriffen: 12. März 2017).
skincage. 2012. Hans Reichel - Le Bal (excerpt). (zugegriffen: 12. März 2017).
2t22tornadosiren. 2013. Daxophone: Hans Reichel - Bubu And His Friends. (zugegriffen: 12. März 2017).
SoundRecordingJP. 2014. スティックやクシを用いる奏法【サンレコ2014年6月号連動】. (zugegriffen: 12. März 2017).
SoundRecordingJP. 2014. ダクソフォンのセッティング法と弓を使った基本奏法【サンレコ2014年6月号連動】. (zugegriffen: 12. März 2017).
O A. Hans Reichel. (zugegriffen: 12. März 2017).
O A. Daxophone. (zugegriffen: 12. März 2017).
O A. Shanghaied on Tor Road, by HANS REICHEL. Destination: OUT store. (zugegriffen: 12. März 2017).
Reichel, Hans. - Flashseite zum Daxophon von Hans Reichel. (zugegriffen: 12. März 2017).
O A. 2015. Daxophon. Wikipedia. 14. Dezember. (zugegriffen: 12. März 2017).

You already have super-power in your eard, which you where not aware of. Steve Mould demonstrates in this video that you can hear without exercising, whether water is cold or warm. Test it yourself.

The reason is that you are already familiar with the sound of pouring water and have stored the information somewhere in your brain. This information is automatically retrieved if you hear the process but do not see it.

Hot water has a lower viscosity than cold. The blubber noise in warm water is slightly higher on average due to its lower viscosity. Our fine hearing sensors are clearly aware of this difference.

You can find more information here:

On ConcertHotels you will find a test that measures your precision of rhythm feeling. Take the test first. Then try singing overtones while you’re doing the test and write your results in the comment below if you like. I look forward to it.

Enlarged right auditory cortex, Wolfgang Saus.

Overtones are usually sung slowly and meditatively, rarely fast and rhythmically (there are exceptions). Overtone singers process sound more in the right hemisphere, drummers more in the left, says Dr. Schneider from Heidelberg University Hospital. Test here how your brain processes sounds.

Is that one of the reasons? An interesting question that has not yet been examined. I suspect that focusing on overtones, at least for the untrained, draws attention away from rhythm.

In my advanced courses, I experience that at first the intonation and sound quality of the keynote suffers when the focus goes entirely to the overtones. Conversely, concentrating on the keynote causes a poorer overtone quality or even complete loss of control of overtone singing. I can immediately recognize from the sound what a student is concentrating on.

If you want to sing polyphonic overtones, i. e. a fundamental melody and an independent overtone melody at the same time, then both tones must receive equal attention. I have developed special exercises for this purpose, which improve the clean control of both notes after a few hours. It would be interesting to examine whether these exercises have an effect on the feeling of rhythm. I will do the rhythm test in my courses as a before-and-after comparison. I’m curious to see what happens.

What are your experiences with rhythm and overtones?


“Ode to Joy”, overtone singing by Wolfgang Saus inside an MRI.

This spectacular dynamic MRI video shows how the tongue moves during overtone singing. The melody of Beethoven’s “Ode to Joy” is created by double resonances which are shaped by the tongue in the mouth and throat. Overtone singing is based on the combination of the second and third resonance frequencies of the vocal tract on a single frequency to increase the volume of a single overtone from the vocal sound.

The second resonance frequency is controlled by the base of the tongue along with the epiglottis. The third resonance frequency is regulated by the space under the tongue, which is larger than it appears in the video, because it also spreads to the side of the tongue frenulum, which covers the space in the image. Overtone singing requires constant fine tuning of the two resonance chambers.

It is not easy to sing in the very loud magnetic resonance tomograph and even record the sound. The noise level is so high that I had to wear hearing protection and couldn’t hear my own overtones. I had to sing by feeling. That the right melody came out is spectacular in itself. It shows that it is possible to develop a body feeling for the exact pitch of the resonances that also works without acoustic control through the ear.

The team in Freiburg has developed highly specialized equipment for recording and filtering. Of course the sound is not HiFi.

MRT footage with kind permission and a big thank you to:
University Hospital Freiburg
Clinic for Radiology – Medical Physics & Institute for Music Medicine
Prof. Dr. Bernhard Richter
Prof. Dr. Dr. Jürgen Hennig
Prof. Dr. Matthias Echternach
(c) 2015