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2 strings · D4–A4 open · A5 at the octave · D key · 1 = D · A perfect fifth, the same interval a violin uses between neighbours. Those two notes are the entire tuning; everything above them is your hand.

Tap a string, or slide along a string and the pitch follows your finger, under a bow that never leaves the strings. On a keyboard the letters on the strings are the ones to press — the inner string is the upper key — hold one and the note holds.

Songs21 songs to play

Every song here is public domain — traditional melodies and classical pieces free for anyone to publish. Pick one to hear it played on the strings, or switch to practice mode and the instrument will wait for you to find each note. Want something else? and share it as a link.

1 more song needs notes this instrument does not have. Changing the tuning brings some of them into reach.

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Virtual Erhu

A playable erhu in your browser, with the thing that makes it the hardest instrument on this site: there is no fingerboard. Your finger presses a string suspended in mid-air, and the note is wherever you decide it is — nothing snaps it to a fret, a marker or a semitone. Hold a string and the bow keeps going; let go and it stops.

There is no fingerboard, and that is the whole instrument

Put a finger anywhere on a string above and the note is there. Not the nearest guide, not the nearest semitone — the actual position, read to the cent and printed under the neck. Slide, and it follows you continuously.

Every fretless instrument makes that claim. What makes the erhu different from the violin and the oud is that those two at least give you a board. An erhu does not. The strings run past a slender round neck with a gap between them and the wood, and every stopped note is a finger pressing a string that is suspended in mid air. There is no fret, no board, and no landmark of any kind to stop the string at a defined point or to catch an error after the fact.

This is why a perfectly tuned erhu can play badly out of tune, and it is the normal state of affairs for a learner rather than a sign of anything being wrong. A guitarist who puts a finger roughly in the right place gets exactly the right note, because a fret decided in advance. A violinist gets roughly the right note and the ear closes the gap. An erhu player gets whatever their hand did, with nothing anywhere in the instrument helping. There is no version of this instrument in which that is untrue, so there is no honest version of this page in which the pitch snaps to a grid.

The note lasts as long as you hold it

Press a string and keep pressing: it keeps sounding. Let go and it stops, leaving almost nothing behind — the bow has left the string, and there is very little in a drum this small to go on ringing.

A bowed string is not struck and released like a tine or a plucked wire. It is driven: the bow keeps feeding energy in, the string never decays while the hair is on it, and the note ends when the player ends it. That is why nothing here is a recording — a recorded note has a length already in it, and a phrase is made of notes whose lengths were chosen while they were sounding. The virtual violin makes that argument at length, and it is the same argument; this page is about what an erhu does that a violin cannot.

The vibrato only goes up

Turn it on and hold a note. The pitch leaves the note, rises, and returns from above.

That is not a stylisation, it is arithmetic on a stretched string. A violinist rocks a finger along a board, moving the stopping point a little each way, so the pitch swings symmetrically around the note. An erhu player presses into a string with nothing behind it — and pressing can only add tension, and adding tension can only raise the pitch. Pressure vibrato (壓揉) is therefore one-directional by construction. It is the same physics that makes a guzheng press a one-way gesture on this site: you can always add tension to a string, and you can never take away what is not there.

It also arrives late rather than from the first instant, by about a fifth of a second, widening over the third of a second after that — because a hand does not start rocking on a hinge. The finger lands, the note speaks, and the pressure follows. That delay is why short notes here come out plain and long ones come out singing without anybody deciding which is which. Switch it off while you are working out where the notes are, which is exactly when it is in the way.

Two strings, and a bow that lives between them

The inner string (內弦, nèi xián) is the one nearest your body and the lower of the two, at D. The outer string (外弦, wài xián) is A — concert A, the note an orchestra gives out. A perfect fifth apart, and that is the entire tuning.

The bow is the surprise for anyone arriving from a Western bowed instrument. Its hair runs permanently between the two strings. It is not lifted on and off; you sound the outer string by pressing the hair outward against it and the inner string by pulling inward, rather than crossing over the top. Two consequences follow, and both are on this page:

  • There is no double stop. No position of the hair touches both strings, so an erhu cannot sound two notes at once. Landing on one string stops the other immediately — which is what happens here if you drag from one to the other.
  • A string change means dealing with the bow. You loosen the hair and work the string past it. The erhu tuner covers that, along with the pegs it is easy to blame first.

The D key and the G key

The selector above changes which note is degree 1, and therefore which finger pattern your hand is using. It does not retune anything: the strings stay at D and A in both.

In the D key the two open strings are degrees 1 and 5 — the tonic and the fifth land under no fingers at all, which is why it is the default and why everything sits comfortably. In the G key they become 5 and 2, and the open inner D turns into degree 5 below the tonic. On an instrument with no landmarks the key is the pattern, which is why this is a real control here rather than the formality it is on our violin and oud pages.

It also decides what you can play. Twenty of the twenty-one songs in the library reach this instrument in the D key, and the twenty-first — Mo Li Hua (茉莉花, Jasmine Flower) — only in G, because it dips to degree 5 below the tonic. In D that would be an A below the open inner string, and there is nothing below the open inner string. In G it is the open inner D itself, so the melody fits the erhu exactly. Nothing is quietly transposed to make a song fit: a song that does not fit is not offered, and the counts above are measured rather than claimed.

What the sound is made of

The string is modelled the way any bowed string is. A bow sets a string into Helmholtz motion — one corner travelling round it, sticking to the hair and slipping back once per cycle — and the force that corner puts on the bridge is a sawtooth. That is classical physics rather than a patch somebody dialled in, and it is as true of an erhu as of a violin, so the string here is shared with our violin rather than re-derived.

The body is where the two instruments stop resembling each other. A violin is a box of carved wood, and its resonances are a handful of individually measured modes that sit wherever the maker put them. An erhu is a drum: a small hardwood resonator (琴筒), open at the back, with a stretched python skin across the front and the bridge standing directly on the skin. A membrane does not have a plate’s spectrum. Its modes are the zeros of a Bessel function, so they are inharmonic and derived — roughly 1 : 1.59 : 2.14 : 2.30 for the first four — and one frequency fixes the whole set. That is why the skin colours the tone instead of reinforcing the string’s harmonics, and it is the model used here.

The drum is also about the size of a fist, so there is nothing to support the bottom of the instrument. The open inner D at 294 Hz is already near the edge of what a box that small can radiate, which is the real reason an erhu is described as nasal and penetrating rather than warm: the skin radiates strongly well above the strings, and there is very little underneath. The model rolls off below that for the same reason our violin rolls off below its own body — leaving it in would render a different, larger instrument.

The rest of the huqin family is not here, on purpose

The erhu is one member of the huqin family, all sharing the two-string, fifth-apart layout: the gaohu a fourth above at G4–D5, the zhonghu a fifth below at G3–D4, and others including the banhu and the piercing jinghu of Beijing opera. Both of the first two are already reviewed on the erhu tuner, so adding them here as extra tunings would cost almost nothing.

They are left out because they are not an erhu at another pitch. A gaohu has a smaller drum and a tighter skin; a zhonghu has a larger one. Shipping them on this page would play an erhu’s body at a gaohu’s pitches and label the result a gaohu, which is a claim about how an instrument sounds that we would not be able to back. The same restraint keeps a cello off our violin page. If you are tuning one, the dial reads any of them.

Playing it with a keyboard

The letter keys shown on the strings sound the two open strings, and the note lasts as long as you hold the key down — let go and the bow comes off.

What a keyboard cannot reach is the rest of the string: there is no key for “and three semitones up”, so stopped notes need a pointer or a finger. That is a real gap rather than an oversight, and it is the same one the oud and the violin have — on a fretless instrument the interesting half is the continuous one, and it is the half that has no keys.

Once it is in tune in your hands

This page is for playing an erhu you do not have. If you do have one, the thing you need is on the other side of the site — and on this instrument more than most, because the wooden pegs and the python skin react to humidity in opposite directions, and because everything about your note spacing is decided by a loop of string most owners never think to move.

The erhu tuner takes it from there: setting D and A against A=440 or the 442 most Chinese orchestras use, what the qianjin (千斤) does to your spacing and where it belongs for the length of your arm, and why a single note that howls is almost always the damper rather than the tuning.

Questions

Does the erhu really have no fingerboard?
None at all, and it is the single most important thing about playing one. A violin, viola or cello gives you a board to press the string against, which fixes the stopping point precisely; an erhu gives you nothing. The two strings run past a slender round neck with a gap between them and the wood, and your fingers press a string that is suspended in mid-air. There is no fret, no board, and no physical landmark anywhere to catch a mistake. That is why a perfectly tuned erhu can still play badly out of tune, and it is why this page does not round your finger to anything.
What is the standard erhu tuning?
D4 on the inner string and A4 on the outer string — a perfect fifth apart, the same interval a violin uses between neighbouring strings. The inner string (內弦, nèi xián) is the one nearest your body and is the lower of the two; the outer string (外弦, wài xián) is A, the note an orchestra tunes to. Those two notes are the entire tuning. Chinese orchestras very commonly sit at A=442 rather than 440, which is about 8 cents sharp and clearly audible on a held note.
Why does the vibrato only bend the note upward?
Because that is the only direction a free string can go. A violinist rolls a finger along a fingerboard, so the pitch swings either side of where the note started and the vibrato is symmetrical. An erhu string has nothing behind it, so pressing harder can only add tension — and adding tension can only raise the pitch. Pressure vibrato (壓揉) therefore leaves from the note, rises, and comes back to it from above; it never dips below. A symmetrical vibrato here would be a violinist’s hand on an instrument that cannot make that shape.
Why can I not play two notes at once?
Because the bow cannot reach two strings at once, and that is the instrument rather than the page. An erhu bow is not lifted on and off the way a violin bow is — its hair runs permanently between the inner and outer strings, and you sound one or the other by pressing outward against the outer string or pulling inward against the inner one. There is no position in which the hair is touching both, so there is no double stop on an erhu. It is also why changing a string means loosening the bow hair and working the string past it.
Why are the guides marked in semitones instead of positions?
Because a semitone tick is geometry and a position is a fingering claim. Where a stop has to sit to raise a pitch by a given interval is true of any stopped string anywhere, so those marks are simply that measurement, crowding toward the bridge exactly as they do on the real instrument. Erhu players do organise the hand into positions (把位), but we have no reviewed chart for them, and the rule our violin page derives its position ladder from is a rule about a major scale on a fingerboard — which is precisely what this instrument does not have. Drawing lines we cannot source, on the one instrument with nothing physical there at all, would be inventing a fact in the place you could least check it.
What is the difference between the D key and the G key?
Which note is degree 1, and therefore which finger pattern your hand uses. Nothing is retuned — the strings stay at D and A either way. In the D key the open strings are degrees 1 and 5, which is why it is the default and why everything sits comfortably. In the G key they become 5 and 2, and the open inner D becomes degree 5 below the tonic. On an instrument with no landmarks, the key is the pattern, and switching between them is most of what early erhu practice is.
Why is Mo Li Hua only offered in the G key?
Because in the D key one of its notes does not exist on the instrument. Jasmine Flower dips to degree 5 below the tonic, which in D would be an A below the open inner string — and there is nothing below the open inner string. In G that same note is the open inner D itself, so the melody fits the erhu exactly. Twenty of the twenty-one songs in our library reach this instrument in D, and the twenty-first only in G, so the key selector is what makes the one Chinese melody in the library playable on the Chinese instrument. Nothing is silently transposed to make a song fit.
Why does the low D sound thin?
Because on a real erhu it does. The resonator is a small hardwood drum about the size of a fist with a stretched python skin over the front, and a box that small cannot radiate 294 Hz — so the open inner string’s fundamental is genuinely weak and the note is carried by its harmonics. That is the whole reason the erhu is described as nasal or penetrating rather than warm: the skin radiates strongly a couple of octaves higher, and there is nothing underneath. A model that let the bottom through would have rendered a small viola.
Is the sound recorded from a real erhu?
No — nothing here is recorded. The string and the body are both synthesised on the spot, which is what lets the note last exactly as long as you hold it and lets the pitch follow your finger a cent at a time. A recording has a length and a pitch already in it, and neither can be taken back out. The trade is that the timbre is a plausible erhu rather than a specific one; see the section on what the sound is made of, which says exactly which numbers are modelled and which are chosen.
Can I learn the erhu on this?
You can learn some real things: what the fifth between the two open strings sounds like, how far apart the notes actually are on a string, why the spacing shrinks as you go up, what a slide does, and — most usefully — how unforgiving a string with nothing behind it is. What a screen cannot give you is the bow arm or the pressure of the left hand, which on this instrument are not details but the technique itself. Treat it as a way to hear the geometry, and get a teacher for the hands.
Got a real one that sounds off?

The erhu tuner listens through your microphone and tells you exactly what has drifted, and by how many cents.

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