What one has to consider about the OPTOSOUND project is that many musical instruments produce sound by vibrating in one or more parts of their own structure. These vibrations are nothing but the source of the acoustic field that, diffusing in the air reach the listener’s ear, it’s clear therefore, that the harmonic content is absolutely identical to that of the vibration that are present in the structure of the musical instrument.
The innovative idea to use optical fibres as a swift communication channel which is immune to the electromagnetic interference, is economic and practically and non degradable, the signals reach a distance of many kilometres. As a transducer of the vibrations of the musical instrument through a sensor integrated in the fibre, the Brag grating (FBG) therefore, from an electrical point of view, is completely passive.
As well as those above mentioned, there are other advantages to this solution, like the reduced sizes of the sensor ( the diameter of a “naked” optical fibre is 125 um), there is a possibility to have more sensors recognised along one optical fibre (multiplexing) and more.
The Bragg grating fibre, fixed on a musical instrument, is able to monitor the vibration during a sound emission. Such vibrations, through a demodulation system, are converted into an electrical signal compatible with the reproductive signal already in use.
The project, in fact, sees also a development of optoelectronic unit able to “probe” the sensors and provide electrical signals on exit suitable to the input of a normal auto diffusion system.
The system, in the whole has all its advantages coming from the use the sensor of the optical fibre:
- Immunity to the electromagnetic interference;
- Good sound reproduction (deletion of linear distortion which are typical of the piezoelectric sensors);
- Flat band (it doesn’t need of an equalizer);
- Reduced dimension of low invasiveness on the musical instrument;
- The possibility of distancing the sensor and the system with a guarantee of a better signal;
- The application to all vibrating instruments.
Every musical instrument has need of electro acoustic transducers in order to transform the wave sounds in electrical signals compatible with the reproduction systems, in audio amplification and registration. In the commercial world there are different types of electro acoustic transducers (electromagnetic pickup, piezoelectric, optical and microphones) for musical instrument widely used.
The pick-up is a devise which is able to transform the chord vibrations of a musical instrument (for example, the electric guitar or the electric base) in to electrical impulses; there are various types of pick- up.
The microphone, instead, is an electrical-mechanical transducer able to convert sound pressure waves into electrical signals.
As for the pick-up, there are different types of microphones that their functioning is based by different technologies and conversion methods.
Such devices are limited by a series of faults that compromise their power: the electromagnetic interference, limited transit band, the necessity to introduce structural changes to the instrument, magnetic interference of the pick-up with metallic chords, reduction of the signal over long distances and feedback problems during live exhibitions.
Other limitations of these devices are:
- The necessity of electronic conditioning in the case of a significant length of the instrument cables – diffusion system.
- Higher cost for high quality cables in order to improve the three points mentioned above.
Optoadvance proposes a photonic pick-up that, by exploiting the technology of the optical fibre, can go through the above mentioned issues.
Who are our potential customers?
In the market for musical instruments we can categorise two types of consumers:
- The occasional one, which is an amateur or a Sunday player, not particularly interested in a low price: such a person chooses wordily brands such as IBANEZ and BONTEMPI, the latter being an Italian make which also produces musical toys.
- The professional one, he is interested more in the quality and he goes especially for the ones made famous by known artists, such as FENDER or GIBSON, highly priced but innovative.
The objective of the project is to realize devices of the highest quality. The proposed systems for sound reproduction are destined to professional artists such as concert players, accordion players and orchestras.