How to Sing Like Sandeul (B1A4): Vocal Range, Mid-Range Support & the Technique Behind It

Singing like Sandeul isn't about a naturally pretty voice — it's about mid-range appoggio breath support that keeps the ribs expanded for a steady airflow, and passaggio technique that uses vowel modification to cross register breaks smoothly. Those two mechanisms are what make the climax of "Slightly Tipsy" and his Immortal Songs live stages land, and they're trainable through focused technique work regardless of your natural voice type.

Safety note: None of the training below should tighten the throat or cause pain. Sustained ballad tones and climactic belting are exactly where breath support failure translates straight into vocal strain — if you feel air leaking or your throat getting tight, drop the key or ease off the intensity. Consult an ENT specialist if hoarseness lasts more than two weeks.

Sandeul's Vocal Profile

Sandeul (Lee Jung-hwan) is the main vocalist of B1A4, a position confirmed consistently across English Wikipedia, Namuwiki, and kprofiles.

Worth flagging: some sources still list B1A4 as signed to WM Entertainment, but that's outdated. B1A4 ended their 14-year contract with the agency on December 23, 2025, and the remaining three members — Sinu, Sandeul, and Gongchan — formed their own label, B1A4 Company (비원에이포컴퍼니). In 2026, marking their 15th debut anniversary, they released the mini album SET and remain an active group.

There is no officially measured, published vocal range for Sandeul. What exists instead is third-party vocal analysis from fan communities, and that data should also be treated as approximate. According to that analysis, he's classified as a light lyric tenor, with a reported full range of roughly A2–A5 (about three octaves). The range he actually supports stably in songs is narrower — roughly C3–B4 — and his mid-range thickness and stability are rated among the stronger examples among male idol vocalists. He reportedly holds stable support up to B♭4, tends to lose support below C3, and reaches A5 only in falsetto, not chest voice.

Two defining axes come out of this profile:

• Mid-range thickness and stability — a narrower but deeply controlled zone, compared to a belting-first high-note approach.
• Dynamic control paired with emotional expression — especially notable on one-take live broadcast stages.

Sandeul's Signature Songs — by Vocal Challenge

Working through his catalog in ascending technical difficulty gives you a natural training order. Note that precise part-by-part vocal assignments within songs aren't consistently documented publicly, so the table below is built on Sandeul's confirmed main-vocalist position plus what the songs themselves demand in range and dynamics.

BPM figures come from algorithmic estimates in the songbpm data family, so treat them as approximate. Start from the top of the table and move down only once each technique is solid. "Slightly Tipsy" is a destination, not a starting point — holding near the support ceiling with emotional expression intact requires the earlier songs' technique to already be in place.

The 3 Techniques Behind Sandeul's Sound

Mid-Range Appoggio Support with Open Ribs

Sandeul's mid-range thickness doesn't happen by accident — it comes from appoggio breath support, keeping the ribs expanded to supply steady subglottal pressure. That support is what fills the C3–B♭4 range without any loss of thickness. On a slow ballad like "Stay As You Are", losing this technique for even a moment shows up immediately as a breath leak on a long tone. The common mistake is pulling the belly inward as the pitch rises, which collapses breath support right when you need it most — the ribs need to stay open instead. Bloom Vocal's A-10 and A-8 exercises train this coordination. The diaphragmatic breathing guide covers the fundamentals behind this kind of sustained support.

Vowel Modification Across the Passaggio

Through the E4–G4 transition, Sandeul narrows the vowel slightly (ah toward uh) to cross into the high range without lifting the larynx. That's the core mechanism behind why his high entries sound seamless rather than pushed. In a fast, choreography-heavy track like "이게 무슨 일이야", this transition has to happen while the body is already under physical load, which roughly doubles the difficulty. The common mistake is pushing the original open vowel straight through as the pitch climbs, which lifts the larynx and presses the tone. Bloom Vocal's C-13 and C-5 exercises train this vowel modification. The belting and passaggio guide and K-pop performance breathing guide round out transition precision and breath control under physical load, respectively.

Dynamic Swells (Messa di Voce)

A volume curve that moves from soft to loud and back to soft within a single sustained note is the technique that makes Sandeul's broadcast live stages so persuasive. It's especially prominent on one-take stages like Immortal Songs, since he has to design an entire three-minute dynamic arc — restrained in the first verse, building toward an explosive back half. The common mistake is trying to build the swell with volume alone, which tightens the throat. A real swell requires precisely controlled vocal fold closure moving together with breath support. Bloom Vocal's F-1 exercise trains this dynamic control.

How to Train Toward Sandeul's Style

Step 1 — Confirm your comfortable mid-range and starting key

Run a range test from your lowest to highest comfortable note, and pick a key where the melody sits comfortably in your mid-range before attempting climactic belting. A stable foundation matters more than chasing exact pitches on the first attempt.

Step 2 — Sustain long notes with appoggio breath support

Keep your ribs expanded and hold a single note for 8+ seconds. Air leaking or the tone wobbling is a sign your ribs have collapsed. This is where the mid-range legato support demanded by a slow ballad like "Stay As You Are" gets built.

Step 3 — Train passaggio vowel modification

Through the E4–G4 range, narrow the vowel slightly (ah toward uh) so you transition without lifting the larynx. Lightly touch your throat or check in a mirror to confirm the larynx isn't rising.

Step 4 — Maintain the transition under physical load

Retry the passaggio transition you just trained while doing light stepping or marching in place. This checks whether your breath stays stable in a choreography-paired song like "이게 무슨 일이야".

Step 5 — Run phrase-level dynamic swells with an AI feedback loop

Record a 4-to-8 bar phrase that moves soft-to-loud-to-soft, then use Bloom Vocal's AI coaching to score your pitch accuracy, breath support, and register transitions. The AI flags habits like lost support mid-swell or laryngeal lift during transitions that are difficult to catch by yourself.

Check Your Cover with AI

Ear-based imitation has a ceiling. It's hard to reliably hear whether your own appoggio support drops out, whether your larynx lifts slightly on the passaggio, or whether your throat tightens mid-swell while you're the one performing. Record the choreography-paired passaggio section of "이게 무슨 일이야" or the climax of "Slightly Tipsy", and Bloom Vocal's AI scores your pitch accuracy, breath support, register transitions, rhythm, and expression on a 1–5 rubric, then recommends exercises targeting your weakest area first. It turns a vague "something felt pressed" into a specific diagnosis: "your larynx lifted on the passaggio transition — train the C-13 vowel modification drill."

For more on how to sing like other K-pop main vocalists, see Eunkwang (BTOB), Kyuhyun, Onew, and Changsub (BTOB).

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References

• Sadolin, C. (2000). Complete Vocal Technique. Shout Publishing. [Vocal mode classification and appoggio-family breath support strategy, plus vowel modification technique across the passaggio.]
• Titze, I. R., & Verdolini Abbott, K. (2012). Vocology: The Science and Practice of Voice Habilitation. National Center for Voice and Speech. [Subglottal pressure management and the vocal fold closure–breath support coordination behind dynamic swells like messa di voce.]