Jukka Rauhala

Fast automatic inharmonicity estimation algorithm

A new algorithm is presented for estimating the inharmonicity coefficient of slightly inharmonic stringed instrument sounds. In the proposed partial frequencies deviation method, the inharmonicity is estimated in an intuitive way by minimizing the deviation of the expected partial frequencies compared to the frequencies of the high amplitude peaks in the spectrum. This is done in an iterative process, where the algorithm converges towards the target estimation value. The algorithm is tested using both synthetic and recorded piano tones. The results show that the new algorithm produces accurate results with a small computation cost compared to other methods.

Tunable dispersion filter design for piano synthesis

The tunable dispersion filter is a new design approach presented in this letter to provide dispersion modeling for digital waveguide synthesis of musical instruments, which do not produce extremely inharmonic sounds, such as the piano. We propose to use a cascade of second-order allpass filters for modeling dispersion. The filter coefficients can be calculated by using simple formulae based on the Thiran allpass filter design, which is usually used for fractional delay approximation. Unlike the previous allpass filter approximations, this filter design is easily scalable to produce various inharmonicity values for a wide range of fundamental frequencies.

Analysis and modeling of piano sustain-pedal effects

This paper describes the main features of the sustain-pedal effect in the piano through signal analysis and presents an algorithm for simulating the effect. The sustain pedal is found to increase the decay time of partials in the middle range of the keyboard, but this effect is not observed in the case of the bass and treble tones. The amplitude beating characteristics of piano tones are measured with and without the sustain pedal engaged, and amplitude envelopes of partial overtone decay are estimated and displayed. It is found that the usage of the sustain pedal introduces interesting distortions of the two-stage decay. The string register response was investigated by removing partials from recorded tones; it was observed that as the string register is free to vibrate, the amount of sympathetic vibrations is increased. The synthesis algorithm, which simulates the string register, is based on 12 string models that correspond to the lowest tones of the piano. The algorithm has been tested with recorded piano tones without the sustain pedal. The objective and subjective results show that the algorithm is able to approximately reproduce the main features of the sustain-pedal effect.

Sparse multi-stage loss filter design for waveguide piano synthesis

A new filter structure and a design method are proposed for the loss filter that is used in digital waveguide synthesis. The main application of this work is the sound synthesis of the piano, but the methods are also applicable to the synthesis of other struck or plucked string instruments. The filter structure is an extension of a sparse FIR filter called the ripple filter, which has been proposed previously for waveguide synthesis of keyboard instruments. The new structure is based on a cascade of sparse FIR filters, which are designed one after the other on subbands that are integer fractions of the audio range. We show by examples that a cascade of three digital filters provides possibilities to exactly match the decay rate of a finite number, such as 50, lowest-order partials, or to approximately match the general trend and some variations of many partials of a piano tone. The subfilters can easily be designed using standard techniques

A parametric piano synthesizer

Synthesizer Jukka Rauhala,∗ Mikael Laurson,† Vesa Valimaki,∗ Heidi-Maria Lehtonen,∗ and Vesa Norilo† ∗Department of Signal Processing and Acoustics Helsinki University of Technology P.O. Box 3000, FI-02015 TKK, Espoo, Finland www.acoustics.hut.fi jukkis@acoustics.hut.fi, {vesa.valimaki, heidi-maria.lehtonen} @tkk.fi †Centre for Music and Technology Sibelius Academy P.O. Box 86, FI-00251, Helsinki, Finland cmt.siba.fi {laurson, vnorilo}@siba.fi

Toward Next-Generation Digital Keyboard Instruments

In this article, alternative approaches to digital keyboard instrument synthesis are looked into. Physics-based sound synthesis, which aims at generating natural-sounding musical instrument tones algorithmically without using a large sample database, is a promising approach. It would provide high-quality music synthesis to systems that cannot afford a large memory, such as mobile phones and portable electronic games. The realistic parametric synthesis of musical instrument sounds is still a challenge, but physical modeling techniques introduced during the last few decades can help to solve it. Recently, the first commercial products have been introduced, for example, by Pianoteq. Three keyboard instruments, the clavichord, the harpsichord, and the grand piano, are focused on here. The sound production principles and acoustics of these instruments are first discussed. Then, the previous parametric synthesis algorithms developed for these instruments are reviewed. The remaining part of this article concentrates on new signal processing methods for parametric synthesis of the piano

Parametric Excitation Model for Waveguide Piano Synthesis

In this paper, a method providing an excitation signal for the waveguide piano synthesis is presented. The waveguide synthesis string model needs an excitation signal, which stimulates the model to resonate at the partial frequencies. This signal simulates the force pulse, which occurs in the piano when the hammer hits the string. In the proposed method, the excitation signal is produced by using additive synthesis with matching partial amplitudes and frequencies, and by adding bandlimited white noise into the signal. The excitation model takes into account the velocity at which the piano key is pressed, using bandstop and lowpass filtering. The proposed method is suitable for real-time piano synthesis, as it is controllable and computationally efficient

A new feature for TV programs: viewer participation through videoconferencing

In this paper, the inclusion of a videoconferencing server is proposed as a new feature for TV broadcast systems. With this feature, TV broadcast stations can enable viewers to participate in TV programs by using a videoconferencing client. Some program concept ideas, such as game, talk, and radio shows, are analyzed in this paper from the features point of view. The technical implementation of the feature is studied by sketching the implementation in a real broadcast system as well as creating a reference implementation, which is tested in a real TV broadcast system. The results show that the feature is possible to implement and it suits well into TV environment, because it provides participation with visual aspect. Hence, it can be easily seen that this feature has its place in a future TV broadcast system.