Pydata Paris Python for manufacturing musical instruments. Context: making and repair of musical instruments. Assets: traditional craftsmanship ; world-famous quality Challenge: aggressive competition from foreign countries

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Python for manufacturing
musical instruments
Olivier CAYROL - June 15th, 2016

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Prolegomena
• A few words about me:
• co-founder and deputy CEO of Logilab
• cuddling computers for 30 years
• data modelling, software design
• A few words about my company:
• created in 2000, 20 engineers today
• Python since the beginning, agile development
• active free software supporter
• development of strategic semantic Web applications:
• data.bnf.fr (national library), francearchives.fr (national archives)
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Context
• Making and repair of musical instruments:
• 2,400 companies in France, 2/3 with only 1 employee
• employees: 11,000 people in France
• turnover: 800 millions Euros / year
• exported production rate: 80%
• Assets:
• traditional craftsmanship
• world-famous quality
• Challenge:
• aggressive competition from foreign countries
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Context illustration
Restoration of baritone saxo from 1901, Gaëtan Schneider
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ITEMM laboratory
• European Technological Institute for Musical Professions
• Based in Le Mans, France
• Designing digital tools dedicated to the manufacturing of musical
instruments:
• characterization of instruments
• analysis of the sounds the instruments produce
• development of digital models to predict the sounds of the instruments
• Driving the digital revolution of the French sector of instruments
craftsmanship
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Needs of the instrument makers
• When designing an instrument, makers are interested in:
• tuning
• timbre
• ease of playing
• Traditionally, makers:
• build multiple prototypes
• in order to choose the proper instrument dimensions
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PAFI platform
• Web application developped by ITEMM and Logilab
• source code to be soon published as free software
• Support for woodwind and brass wind instruments:
• trumpets, horns, trombones, saxophones, clarinets, oboes, etc.
• Dedicated digital tools:
• instrument models, fingering descriptions
• computation of acoustic input impedance for a given fingering
• tuning diagram for each fingering
• capture of acoustic input impedance from a real instrument
• Ability to share and clone instrument models
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PAFI platform overview
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Use case 1 - introduction
• Project made by Baptiste Le Guillou
• student at the ITEMM
• in the context of his degree in Arts and Crafts (Brevet des Métiers d'Art)
• project duration: 2 years
• Turning a valves trumpet into a valves and slide trumpet
• the added slide must modify the note up to one tone
• the added slide allows playing quarter tones or glissando effects
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Use case 1 - work to be done
• Add tubings in the tuning slide to allow the desired effect
• Remove a part of the tubing between the bell and the valves
• in order to have a longer space for the tuning slide
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Use case 1 - study
• Questions to be answered:
• what length of tubing should be added to the tuning slide?
• what are the effects of the modifications on the instrument?
• Use of the digital simulation instead of numerous trial / error cycles:
• cheaper, faster
• ability to explore more possibilities
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Use case 1 - geometry
• Measure of the actual instrument:
• tubings length and diameter
• valves position
• Description of the instrument in the platform:
• series of tubings, cones, valves, returns, holes, etc.
• different fingerings:
• which holes are closed, half-closed, opened
• which valve pistons are pushed
• what note is expected
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Use case 1 - computation
• Computation of the acoustic impedance:
• Fourier transform of the pressure divided by the volume flow
• shows the resonance frequencies of the instrument
• and thus the notes that can be played
• Computation of the tuning diagram:
• difference between the expected note and the actual note (computed above)
• the musician must adjust his playing to correct the note:
• small differences mean ease of playing
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Use case 1 - results
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Use case 1 - checking
• Measure of the actual acoustic impedance of the instrument
• with dedicated sensors (loudspeakers and microphone)
• connection through the Web browser thanks to the Web audio API
• Comparison of the two impedance graphs
• especially the resonance frequencies
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Use case 1 - measures
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Use case 1 - conclusion
• Different slide lengths have been simulated
• The best option has been implemented on the instrument
• The result perfectly meets the initial requirements
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Use case 2 - introduction
• Project made by Gaëtan Schneider
• student at the ITEMM
• in the context of his degree in Arts and Crafts (Brevet des Métiers d'Art)
• project duration: 2 years
• Restoring a Couesnon baritone saxo from 1901
• numerous keys are twisted
• the neck is smashed and splitted
• it can't be restored
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Use case 2 - initial state
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Use case 2 - study
• A new neck must be built
• Question to be answered:
• what must be the length and the shape of the neck?
• Study:
• geometry description
• computation of tuning diagram
• digital try of different necks
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Use case 2 - model
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Use case 2 - results
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Under the hood
• Web application coded in Python and javascript
• Computations based on numpy and scipy libraries
• refactored from Matlab prototypes
• Simple model and simple computations
• easy to describe
• fast to compute
• sufficient accuracy for the expected physical values
• the played note corresponds to the first order in physics
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Feedbacks
• Craftsmen:
• easy test of instrument designs with a digital tool
• ability to explore and dig in several options
• no installation (Web application)
• Researchers:
• easy-to-understand code
• Python compactness, high-level operations in its numeric libraries
• structuring in modules
• security from the numerous automatic tests
• ability to enhance the algorithms without regression
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We are hiring!
• Visit http://www.logilab.fr/emplois
• Web developer (javascript + Python)
• Developer for data analysis and semantic Web (Python)
• Thank you for your attention
• Email: olivier.cayrol@logilab.fr
• Twitter: @OCayrol
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