The document outlines the application of Python in the design and manufacturing of musical instruments, describing a web platform (pafi) developed for facilitating digital tools for instrument makers. It highlights the challenges faced by the industry, the digital revolution led by the ITEMM laboratory in France, and provides use cases demonstrating how digital simulation reduces the need for physical prototypes. The text concludes with an emphasis on the platform's benefits for both craftsmen and researchers, along with a call for job applications.

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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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