Christoph Reuter

Register Classification by Timbre

The aim of this analysis is the demonstration that the high and the low musical register (Soprano, Alto vs. Tenor, Bass) can be identified by timbre, i.e. after pitch information is eliminated from the spectrum. This is achieved by means of pitch free characteristics of spectral densities of voices and instruments, namely by means of masses and widths of peaks of the first 13 partials (cp. Weihs and Ligges (2003b)). Different analyses based on the tones in the classical song ?Tochter Zion? composed by G.F. Handel are presented. Results are very promising. E.g., if the characteristics are averaged over all tones, then female and male singers can be easily distinguished without any error (prediction error of 0%)! Moreover, stepwise linear discriminant analysis can be used to separate even the females together with 28 high instruments (?playing? the Alto version of the song) from the males together with 20 low instruments (playing the Bass version) with a prediction error of 4%. Also, individual tones are analysed, and the statistical results are discussed and interpreted from acoustics point of view.

Karl Erich Schumann's Principles of Timbre as a Helpful Tool in Stream Segregation Research

The following text deals with timbre-dependent stream segregation. Combining the ideas of Gestalt principles, auditory scene analysis and Schumanns principles of timbre, the following hypotheses are proposed and examined: (i) Alternating timbres with matching formant positions are perceived for the most part as one sole melodic stream. (ii) Alternating timbres with non-matching formant positions are perceived for the most part as two interwoven melodic streams. (iii) Alternating timbres which have on the one hand formants and on the other hand fluctuations as primary attributes are perceived for the most part as two interwoven melodic streams. (iv) Alternating timbres of which the main attributes are fluctuations are perceived for the most part as one sole melodic stream. In this experiment based on Wessel (1985), hypotheses 2 and 3 were fully confirmed, whereas hypotheses 1 and 4 could not be fully confirmed. Possible causes for this are discussed: the invariable melodic contour of the stimuli as well as the tempo in which they were played; furthermore, the mental situation of the subjects at the time of the experiment.

The role of formant positions and micro‐modulations in blending and partial masking of musical instruments.

In experiments about the distinction of instruments playing in unison, it has been shown that timbres with overlapping formant areas are blending homogeneously whereas timbres with different formant areas are distinguishable very well (Reuter, 1996). On the other hand timbre separation is enhanced by micro‐modulations and vibratos [e.g., McAdams (1982); Reuter (2007)]. The aim of this contribution is to find out to what extent timbre separation is influenced by different micro‐modulations/vibratos versus different formant positions. 30 subjects listened to scale fragments of simultaneous playing instruments with equivalent formant areas and with different formant areas, with and without starting/ending transients, and with and without vibratos/micro‐modulations. They had to answer the following question: Do you hear one sole instrument (or two of the same instruments) or do you hear two different instruments? In almost all cases featuring equivalent formant areas most of the subjects perceived one blendin...

The octave illusion and handedness: A replication of Deutsch’s 1974 study

The octave illusion was first described by Diana Deutsch in 1974; in this phenomenon, a dichotic sequence of oscillating 400 and 800 Hz sinusoidal tones evokes different illusory percepts. At the same time, the obtained percepts were found to be dependent on the subjects’ handedness. This study investigates the influence of the handedness classification method on the correlation between reported percept and handedness in the octave illusion. After presenting the stimulus, we asked a total of 174 subjects to report their percepts and complete a handedness inventory as well as a speed tapping task. According to the right shift theory of Annett (1972, 2002) and a related study by Kopiez, Galley, and Lehmann (2010), we hypothesized that the use of performance measurement to classify handedness may clarify ambiguous correlations of subjects’ handedness with some obtained illusionary percepts. The results support the general findings of Deutsch but show that stronger effects can be found if hand performance differences are used for handedness classification. A better separation between the handedness groups could be observed, especially for the complex perception patterns.

Virtual wind instruments based on pulse forming synthesis

A new synthesis method for wind instruments is presented, the digital pulse forming. The core of that principle is that every wind instrument sound can basically be put down to its excitation impulses, which independently of the fundamental always behave according to the same principles. By controlling the pulse width and shape it is possible to generate all sound nuances that can be produced on a real wind instrument. Based on the 1975 found principles of generating wind‐instrument‐like spectra with typical stable formant areas and spectral gaps evoked by the excitation pulses of double‐reeds or lips [J. P. Fricke, Fortsch. Akust. 4(DAGA75), 407–411 (1975)], a virtual wind instrument, the Digital Variophon, is developed. The resulting software‐based version of the original Variophon, the first analog wind synthesizer using the pulse forming principles, is a further step towards the intended scientific experiment system for analyzing and synthesizing (wind) instrument sounds. Trumpet, bassoon, and oboe mo...

Audio quality in everyday listening situations

The quality of digital audio which uses a form of lossy data compression is in the focus of several studies. The experimental focus of these studies includes the fundamental difference between objective and subjective measurement methods (Pocta & Beerends, 2015), test standards (Breebaart, 2015), or signal processing (Khaldi et al., 2013; Jung et al., 2016). But there are only few studies concerning the impact of perceived quality differences in everyday listening situations (ELS). Short excerpts of recent popular music recordings were encoded with different bit rates based on codecs that are commonly used by popular music streaming services. While the encoded files were presented via standard Samsung in-ear headphones, the everyday listening situation was simulated by using binaural recordings of a shopping mall soundscape that was simultaneously presented via Stax electrostatic headphones. In a control condition no soundscape was used. The stimuli were rated by 30 participants in a MUSHRA listening test...

A synthesis and analysis framework for wind instrument sounds based on the digital pulse forming principle

A digital real‐time‐capable analysis‐ and synthesis‐system for wind instrument sounds, based on the pulse forming theory, has been developed. The rediscovered model for the sound generating process of wind instruments rests upon the idea, that wind instrument sounds can basically be put down to its excitation impulses, which independently of the fundamental always behave according to the same principles. First realised in the analogue wind instrument synthesizer Realton Variophon (1975), the sound synthesis method has currently been transferred onto a digital platform [supported by the German Research Foundation]. Instrument specific algorithms control the pulse width and shape according to the applied pitch and dynamic values. That way subtle sound nuances that can be produced on acoustic wind instruments as well as real timbre modulation may be synthesized by just modifying a single parameter (i.e. breath pressure). In order to validate the performance of the developed framework, several perception expe...

Dynamic Excitation Impulse Modification as a Foundation of a Synthesis and Analysis System for Wind Instrument Sounds

The Variophon is a wind synthesizer that was developed at the Musicological Institute of the University of Cologne in the 1970/80ies and was at that time based on a completely new synthesis principle: the pulse forming process. The central idea of that principle is that every wind instrument sound can basically be traced back to its excitation pulses, which independently of the fundamental always act upon the same principles. In a recent project, supported by the German Research Foundation (DFG), the synthesis method of excitation impulse modification has been transferred to a digital platform.