Resonator Tuning, The Key to Whistle Voice
03/10/2025
If you’ve ever tipped your head back trying to hit those super-high, shimmering whistle notes and come up empty-handed, you’re not alone.
This is exactly what happened to Célia, who joined The singsing! Sofa Intensive to work on her falsetto and whistle voice. She loved those 5 days so much that she subscribed to The singsing! Sofa Library right after. Just like all Library members, she gets to participate for free in the monthly Ask-Me-Anything webinars.
In her first AMA, she asked this question:
“During the Intensive, we mainly worked on falsetto. For this AMA, I’d like to know the anatomical differences with whistle and what your best tips are for singing it. I have never managed to produce it through creaking.”
OF COURSE this question made me so excited that I decided to turn my reply into a blog post and share the goodies with you.
Honestly, I have taken Célia’s question as permission to put my geek hat on and go above and beyond in nerdland. But no worries! I’ll also share loads of practical tips & tricks and do’s & don’ts, so you can channel your inner Mariah Carey immediately.
First of all: Here’s a video that will give your ears immediate understanding of what whistle voice is.
The Difference Between Whistle and Falsetto: Nerdland!
WARNING: In this chapter, you enter nerdland – don’t say I didn’t warn you. If you don’t care about this geeky stuff and just want to sing, scroll down to How To Sing in Whistle Voice: Principles and Strategies!
Falsetto – A quick recap
In my blog post What Is Falsetto, Really? And Is It Really That Easy?, I explained falsetto in detail from the standpoint of Complete Vocal Technique (CVT), classical pedagogy, Speech Level Singing (SLS), Estill, and others – go check it out!
Here’s the short version: CVT says it is a thin and “hollow” variation of Neutral, which they used to call flageolet. So a lot of the elements of Neutral apply, but there are some distinct differences.
Here’s an overview I made combining CVT with the most recent research:
- Vocal fold Mass & Vibration:
Vibration takes place over the full length of the vocal folds, but only the thin edges, called the cover, vibrate. The body of the folds is relaxed and does not engage much in vibration. - Vocal fold Closure:
Can be complete or incomplete. When incomplete, there’s a gap at the back of the vocal folds, which produces a soft, airy quality to the sound. The open phase of the vocal folds lasts longer than the closed phase. - Subglottal pressure:
Mostly low, but moderate when volume is louder (“countertenor falsetto”). - Resonance:
The vocal tract shapes the color of your sound by boosting/attenuating overtones. There’s a lot of versatility in Neutral, so also in falsetto: you can go from very dark to very light.
- Airflow:
Higher than metallic singing / M1 / chest voice / modal. (Neutral is non-metallic / M2 / head voice).
- Pitch range:
CVT says you can sing falsetto on all pitches, but it’s quite difficult to do and tends to disappear in the low part of your voice. The higher you go, the easier it becomes. Many singers can go up to around C6–E6 (higher for some).
Whistle Voice – A whole different animal
Frankly, the term whistle voice is misleading. Anatomically, it has nothing to do with the way we produce an actual whistle with our lips. In reality, it is created entirely by the vocal folds and the vocal tract. The name stuck because of the bright, piercing timbre, but it doesn’t reflect the underlying physiology.
In classical singing, whistle voice used to be called flageolet, flute register, or bell register, but now it is more often called M3, a separate mechanism from M1 (chest) and M2 (head).
Complete Vocal Institute shares very minimal information on their understanding of whistle voice – which is the high part of what they too used to call flageolet – on their website.
Here’s a combination of what I learned while studying to become an Authorized CVT Teacher from 2011 to 2014, my own research from 2015, and a whole bunch of research papers (see the resources below this article).
- Vocal fold Mass & Vibration:
The vocal folds are elongated to the extreme, are extremely thin, and in some versions of whistle, only the anterior part of the vocal folds vibrates. Yes, you read that right: partial vibration of the vocal folds!
- Vocal fold Closure:
Sometimes complete, but in many cases, there is incomplete glottal closure. Several patterns are possible: a gap along the full length of the vocal folds, at the posterior part, at the anterior part, or at both ends.
- Subglottal pressure:
Researchers do not agree. Some say low, others say very high. Different study populations and styles (operatic coloratura vs. pop whistle) and different measurement methods produce different results. - Resonance:
A strong fundamental and weak overtones in comparison to other laryngeal mechanisms. - Airflow: Low.
- Pitch range:
Researchers’ opinions on where whistle voice starts vary, but it is commonly said to start around C6. They all agree that it goes wayyyyyy above C6!
The highest vocal note by a female is often claimed as G10 (over 25,000 Hz – out of the range of most human ears) by Brazilian singer Rossana Monti, who uses the stage name Georgia Brown. However, that “record” is contested and Guinness World Records currently does not mention it on their website.
The highest vocal note by a male registered by Guinness World Records is F#8 (5989 Hz), achieved by Amirhossein Molaei (Iran) on 31 July 2019.
Researchers have suggested that this very high whistle – sometimes called M4 or glottal whistle – might be produced with a special “vortex whistle” mechanism in the larynx. More research is needed, but it may be that an aeroacoustic mechanism plays a key role, rather than normal vocal fold vibration. This would mean that the airflow itself creates the sound – like the ultrasonic vocalizations of rodents (!).
How To Sing in Whistle Voice: Principles and Strategies
Let’s switch gears: now that you have a “map” from nerdland, here’s how to start exploring the territory.
Célia is an Authorized CVT Teacher, which is why she mentioned trying creaking. Indeed, creak(ing) / vocal fry as an onset is a common and often successful CVT strategy, but recent studies suggest resonator tuning and minimal subglottal pressure are even more decisive.
Reso-what? Sub-what? Continue reading…
Some singers find creaking “locks” their vocal folds instead of freeing them. Whistle voice is not about muscular squeezing. It’s about letting only the thin edges of your vocal folds vibrate, and using the resonator (your throat, mouth and nose) as an amplifier.
Here are my Top 3 Principles:
- Reduce vocal fold mass participation by using light phonation (a fancy word for making sound with your voice) and a mindset of disengagement
.
- Avoid air pressure buildup below your vocal folds, so no pushing or breath-holding! When you try to “push” into whistle by adding pressure, you’ll hit a ceiling. Your voice will either break or get stuck.
- Resonator tuning: Shape your vocal tract (another fancy word for your throat, mouth, and nose) to find an easy access point by boosting high harmonics.
Here’s the video with those beautiful examples of whistle again. Notice how these singers apply perfect resonator tuning!
- Smile – lift those cheeks!
- Open relaxed jaw without losing your smile.
- High larynx.
- High back of the tongue.
- Closed nasal passages.
- The æ vowel as in “cat” works for many people, but it’s good to experiment with nearby vowels.
Strategies to sing in whistle / flute / bell / flageolet / M3 / whateveryawannacallit
Research shows that a vocal sound is often produced by many different strategies across singers. A single technique will not work for everyone, and the same goes for whistle voice.
So here’s a menu of strategies that came up during the webinar. Remember to always apply the top 3 principles while experimenting:
- Invite the lightest creak(ing) / fry possible on your highest note, then slide up with minimal airflow. Abort this strategy if you notice you’re squeezing too much.
- Sing a whispery siren on the inhale – yes, the inhale – from C6 upward. Then try to exhale the same pitch gently.
- Start in a high falsetto and “sneak” higher with the least volume possible.
- Say “pew pew” / [piæ] [piæ] like a sci-fi gun and aim for a pitch higher than C6. The P helps you “focus” the sound. It should feel like tiny air puffs from behind your eyes.
- Imitate bird chirps or a whining puppy.
- Cackle like a witch, but nearly without a sound.
- Use a laugh-like onset with the tiniest H possible: “Hæ-hæ-hæ” with airiness, sparkle, and baby-voice energy.
- Say the phrase “Ha! I did it!” in your highest squeaky voice. Emphasize the “did” like a pop. The D helps you close your nasal passages. Allow it to go higher each time. Eventually, try holding “did” or “it” as the sustained pitch.
- Shape your mouth as if you’re singing the note – remember the resonator tuning. Imagine the sound, but initially don’t make it. Then let a tiny, focused tone out, almost like letting air escape a balloon.
- Helpful cues:
“Let the sound happen to you, don’t make it”
“Creep into the pitch instead of shoving.”
“Walking up stairs in soft socks instead of heavy boots”
“Less like blowing air through a straw, more like pinging a crystal glass.“
“Invite the sound from above your eyes / above your soft palate.”
Because every singer’s anatomy and coordination are different, the same trick won’t work for everyone.
Mix, match, and persist.
What worked for you? Let me know in the comments!
If you want access to the full replay of this AMA on whistle ànd a collection of 45+ highly educational webinars, 65+ hours of content, consider joining The singsing! Sofa Library. I lead these Ask-Me-Anything webinars once a month, and Library members get to participate for free.
Together, we’ll explore what your voice is capable of.
This session was a great add-on to my voice lessons with Sarah!
M.J. Johnson - Singer & Voice teacher
Susanne Vahle - Vocational singer
Bec Tilley, Voice Coach & Singer
Ariane De Dom, Avocational singer
Susanne Vahle - Vocational singer
Ariane De Dom, Avocational singer
RESOURCES
- Biomechanics of sound production in high-pitched classical singing – Echternach et al. (2024)
- Vocal Fold Vibration of the Whistle Register Observed by High-Speed Digital Imaging – Kato et al. (2023)
- What is glottal whistle? – Exploring extremely high fundamental frequencies in human vocal production – Wingerath and Grawunder (2023)
- Differences Among Mixed, Chest, and Falsetto Registers: A Multiparametric Study – Lee et al. (2023)
- 13 Sounds Humans Can’t Hear – Grunge Magazine (2023)
- Characterizing Vocal Tract Dimensions in the Vocal Modes Using Magnetic Resonance Imaging – Leppävuori et al. (2020)
- The Vibratory Pattern of the Vocal Folds in the Four Vocal Modes and Flageolet of Complete Vocal Technique (CVT) – A Videokymographic Study (VKG) – Algoet et al. (2015)
- Relationship between nasal valve changes and nasalance of the voice – Gerek et al. (2012)
- Pitch profile of the glottal whistle (M4) – Edgerton (2013)
- Glottal behavior in the high soprano range and the transition to the whistle register – Garnier et al. (2012)
- On vibration properties of human vocal folds: voice registers, bifurcations, resonance characteristics, development and application of videokymography – Jan Svec (2000)
- Physical definition of the “flageolet register” – Miller et al. (1993)
- Whistle register of the singing voice: HSDI evidence – Di Corcia and Fussi
- Description and sound of Neutral – Complete Vocal Institute Research Site
- Complete Vocal Technique
As always, feel free to send me your thoughts, questions, and feedback in the comments below this blog, via the contact form or in the singsing! online community 
Cordially,
Sarah