draft 2026-10-17
last checked 2026-10-17
How we work
Most people's first worry about AI and creative work is that it flattens the work and the people behind it. These are the rules we hold ourselves to instead.
Principles
- Fit the person. The interface bends to you. Agents refit it while you use it, inside limits you set.
- Fit, then check. An instrument is fitted to real recordings. Its numbers steer only after they agree with your ear, in a blind test.
- Collaborate where the value is. The agents do the engineering. You are asked only where your taste, your senses or your decision count, and then precisely.
- Deterministic parts, evolving structure. Agents build on deterministic operations, the layer everything else rests on, and keep adding to it until it matches the real thing. That is where the precision comes from.
- Yours, locally, in any harness. Your agent, your harness, your machine.
- Give back, and say where it came from. Open source. Credit the recordings and the people an instrument was measured from. Culture preserved, not flattened.
Words we use
| luthiers for agents | We make the parts, your agents make the instrument, and you say when it fits. |
| fitted interface | An interface fitted to its person the way an instrument is fitted to a recording: tuned to how they actually answer, and changed by the same loop. |
| collaborating where the value is | The agent does the measurable work. The person is asked only where their taste decides. |
| taste-in-the-loop | The person's taste is what the agent calibrates against, not a checkpoint that approves. |
| zero-time-iteration | When building an idea costs so little time that you find out whether it is useful by having the agent build it and using it straight away. |
| agent-shaped, human-shaped | The interface is agent-shaped on the agent side and human-shaped on the human side. |
| human-machine middleware | What ismail is: it sits between the person and the machine, turning what they perceive and do into operations, and adapting to their feedback. |
Credit where credit is due
Giving credit is giving thanks. It pays something back, even if it only means one more person knows the work exists.
This is all based on a part other people's research and a part my persistence, taste, and my earNate, who started Measured Instruments
Every piece made with ismail carries its own credits file, written by the agent: "Made with ismail" and every recording it measured to model a sound. How to credit ismail.
People and crafts
- The luthier's craft: The model for Measured Instruments: a maker who measures an instrument and fits it to the player.
- Speech science of the 1970s: Why our measured voice is built from numbers you can direct, measured from real recordings, and not cloned by a neural model.
Methods our code builds on
- pYIN pitch tracking (Mauch and Dixon, ICASSP 2014): Pitch and voicing for melody reads and for instruments measured from recordings.
- YIN pitch estimator (de Cheveigné and Kawahara, JASA 2002): Fine pitch per frame on top of pYIN's reading.
- ITU-R BS.1770 loudness and EBU R128: Loudness targets and true-peak checks for mastering and for fair comparisons, measured with pyloudnorm (Christian Steinmetz).
- Digital waveguide synthesis (Julius O. Smith III, Physical Audio Signal Processing): Plucked strings for the electric guitar and bass.
- Topology-preserving state-variable filter (Vadim Zavalishin, The Art of VA Filter Design): The synth filter, studio and live.
- PolyBLEP oscillators (Välimäki and Huovilainen, IEEE Signal Processing Magazine 2007): Alias-reduced saw and square waves.
- Freeverb (Jezar at Dreampoint, public domain): The reverb, studio and live.
- Modal synthesis: A 1970s drum kit as banks of resonators struck by the stick.
- Key profiles (Carol Krumhansl): Key estimates for a song or a range of bars.
- Linear prediction (LPC) formant tracking: The vowel view of a voice.
- Hybrid Transformer Demucs (Rouard, Massa and Défossez, 2023): Stem separation of a reference, so the agent compares drums with drums and bass with bass.
- LAION-CLAP audio embeddings (Wu, Chen and others, ICASSP 2023): A perceptual similarity score next to the hand-made metrics.
- librosa (McFee and others, SciPy 2015): The audio analysis library under pitch, LPC and spectra.
- VocalSet (Wilkins, Seetharaman, Wahl and Pardo, ISMIR 2018), CC BY 4.0: Sung vowels and vibrato habits from open recordings.
- WORLD vocoder (Morise, Yokomori and Ozawa, IEICE 2016): Splits a voice into pitch, envelope and breath, so the autotune effect moves the pitch and leaves the rest.
- Tone-stack model (Yeh and Smith, DAFx 2006): The amp's tone stack as an analytic filter.
- Moog ladder model (Antti Huovilainen, DAFx 2004): A light four-pole ladder filter, studio and live.
- Crosstalk cancellation (Atal and Schroeder, Bell Labs, US patent 3,236,949): The crosstalk canceller in the spatial audio code.
- Dennis Klatt, aspiration (JSHR 1975): Aspiration in the measured voice, and with his 1979 chapter, "Synthesis by rule of segmental durations in English sentences" (Frontiers of Speech Communication Research, Lindblom and Öhman, eds.), its duration rules.
Neighbours and earlier ground
- Spectral Modeling Synthesis (Serra and Smith, Computer Music Journal 1990): Our instruments measured from recordings play a note as harmonics plus shaped noise, the split SMS describes.
- Strudel and TidalCycles (Felix Roos, Alex McLean and contributors): Earlier ground: our first experiments with language models writing music ran on Strudel, before ismail.
- synth-rl and LLM2Fx-Tools (Sony AI and KAIST): Neighbours: work that also measures sound against a reference.
- RIME and Libretto (Schaffer and Singh, Dartmouth; Yichen Xu, Berkeley): Research on agents doing music work with tools and measured feedback.
- The Continuator (François Pachet, Sony CSL, Journal of New Music Research 2003): An early system that played back in the style of a live player.
The company
Measured Instruments LLC, a Wyoming limited liability company. It makes the instruments and interfaces on this site and publishes them as open source. Write to hello@measuredinstruments.com.