Summary To form a coherent percept of the environment, our brain combines information from different senses. Such multisensory integration occurs in higher association cortices; but supposedly, it also occurs in early sensory areas. Confirming the latter hypothesis, we unequivocally demonstrate supra-additive integration of touch and sound stimulation at the second stage of the auditory cortex. Using high-resolution fMRI of the macaque monkey, we quantified the integration of auditory broad-band noise and tactile stimulation of hand and foot in anaesthetized animals. Integration was found posterior to and along the lateral side of the primary auditory cortex in the caudal auditory belt. Integration was stronger for temporally coincident stimuli and obeyed the principle of inverse effectiveness: greater enhancement for less effective stimuli. These findings demonstrates that multisensory integration occurs early and close to primary sensory areas and—because it occurs in anaesthetized animals—suggests that this integration is mediated by preattentive bottom-up mechanisms.

Integration of touch and sound in auditory cortex

The first artificial reverberation algorithms were proposed in the early 1960s, and new, improved algorithms are published regularly. These algorithms have been widely used in music production since the 1970s, and now find applications in new fields, such as game audio. This overview article provides a unified review of the various approaches to digital artificial reverberation. The three main categories have been delay networks, convolution-based algorithms, and physical room models. Delay-network and convolution techniques have been competing in popularity in the music technology field, and are often employed to produce a desired perceptual or artistic effect. In applications including virtual reality, predictive acoustic modeling, and computer-aided design of acoustic spaces, accuracy is desired, and physical models have been mainly used, although, due to their computational complexity, they are currently mainly used for simplified geometries or to generate reverberation impulse responses for use with a convolution method. With the increase of computing power, all these approaches will be available in real time. A recent trend in audio technology is the emulation of analog artificial reverberation units, such as spring reverberators, using signal processing algorithms. As a case study we present an improved parametric model for a spring reverberation unit.

Fifty Years of Artificial Reverberation

This article describes physical modelling techniques that can be used for simulating musical instruments. The methods are closely related to digital signal processing. They discretize the system with respect to time, because the aim is to run the simulation using a computer. The physics-based modelling methods can be classified as mass–spring, modal, wave digital, finite difference, digital waveguide and source–filter models. We present the basic theory and a discussion on possible extensions for each modelling technique. For some methods, a simple model example is chosen from the existing literature demonstrating a typical use of the method. For instance, in the case of the digital waveguide modelling technique a vibrating string model is discussed, and in the case of the wave digital filter technique we present a classical piano hammer model. We tackle some nonlinear and time-varying models and include new results on the digital waveguide modelling of a nonlinear string. Current trends and future directions in physical modelling of musical instruments are discussed.

/pdf/discrete-time-modelling-of-musical-instruments-1r9oz1ciko.pdf

Discrete-time modelling of musical instruments

The concept of augmented reality audio characterizes techniques where a real sound environment is extended with virtual auditory environments and communications scenarios. A framework is introduced for mobile augmented reality audio (MARA) based on a specific headset configuration where binaural microphone elements are integrated into stereo earphones. When microphone signals are routed directly to the earphones, a user is exposed to a pseudoacoustic representation of the real environment. Virtual sound events are then mixed with microphone signals to produce a hybrid, an augmented reality audio representation, for the user. An overview of related technology, literature, and application scenarios is provided. Listening test results with a prototype system show that the proposed system has interesting properties. For example, in some cases listeners found it very difficult to determine which sound sources in an augmented reality audio representation are real and which are virtual.

/pdf/augmented-reality-audio-for-mobile-and-wearable-appliances-1nqv7fjkos.pdf

Augmented reality audio for mobile and wearable appliances

distribute and/or modify this document under the terms of the GNU Free Documentation License, Version 1.2 or any later version published by the Free Software Foundation; with no Invariant Sections, no Front-Cover Texts, and no Back-Cover Texts. A copy of the license is included in the section entitled \" GNU Free Documentation License \". To scratch means to drag a vinyl record forwards and backwards against the needle on an ordinary turntable along the grooves, not across, though it might sound like it. This way of producing sounds has during the last two decades made the turntable become a popular instrument for both solo and ensemble playing in different musical styles, still mostly in the hip-hop style where Disk Jockeys (DJs) first started to scratch. However, all musical genres seem to be able to adopt the turntables into their instrumental setups. Composers in traditions like rock, metal, pop, disco, jazz, experimental music, film music, contemporary music and numerous others have been experimenting with DJs the past years. Experimental DJs and most hip-hop DJs now frequently call 221 222 The Sounding Object themselves \" turntablists \" , and the music style of scratching and extensive cut-and-paste mixing is called \" turntablism \". These terms, derived from the word turntable, are now generally accepted. It is also generally accepted that a turn-tablist is a musician and that the turntable is to be considered an instrument. The acoustics of scratching has been barely studied until now. On the other end the business market of DJs equipment is quite large. It is therefore interesting to study the phenomenon of turntablism from a scientific point of view. In this chapter three experiments are presented. Aim of these experiments is to model scratching based on analysis of an experienced performer. For this purpose scratching as an expressive musical playing-style is looked at from different views. Experiment 1 investigates the musical fundamentals of scratching , and explains the most common playing-techniques in more detail. Experiment 2 investigates a real performance with aid of sensors on the equipment in order to understand what kinds of problems and parameter variation a model will need to deal with. Experiment 3 investigates what happens to the record that is being scratched, as it is apparent that some heavy damage will be done to the vinyl and this can therefore affect the sound quality. All the experiments shared part of the equipment …

The Sounding Object

Listening tests were conducted to find the audibility of inharmonicity in musical sounds produced by stringed instruments, such as the piano or the guitar. The audibility threshold of inharmonicity was measured at five fundamental frequencies. Results show that the detection of inharmonicity is strongly dependent on the fundamental frequency f0. A simple model is presented for estimating the threshold as a function of f0. The need to implement inharmonicity in digital sound synthesis is discussed.

/pdf/audibility-of-the-timbral-effects-of-inharmonicity-in-2uwufzo1gm.pdf

Audibility of the timbral effects of inharmonicity in stringed instrument tones

More About This Reverberation Science: Perceptually Good Late Reverberation

The physical principles of room reverberation are known well and can be measured or modeled computationally fairly accurately. From a frequency domain point of view, room responses are composed of eigenmodes, i.e., decaying sinusoids with modal density N mode (modes per Hz) increasing as a function of frequency f by N mode) f * + 4πV f 2 c3, where V is the volume of the room and c the velocity of sound [1]. Below a critical frequency the modes are increasingly sparse and may be perceived as separate resonant components if they are strong enough.

Reverberation Modeling Using Velvet Noise

An experiment was conducted to study the effects of force produced by active touch on vibrotactile perceptual thresholds. The task consisted in pressing the fingertip against a flat rigid surface that provided either sinusoidal or broadband vibration. Three force levels were considered, ranging from light touch to hard press. Finger contact areas were measured during the experiment, showing positive correlation with the respective applied forces. Significant effects on thresholds were found for vibration type and force level. Moreover, possibly due to the concurrent effect of large (unconstrained) finger contact areas, active pressing forces, and long duration stimuli, the measured perceptual thresholds are considerably lower than what previously reported in the literature.

/pdf/vibrotactile-sensitivity-in-active-touch-effect-of-pressing-am3s1kmo5b.pdf

Vibrotactile Sensitivity in Active Touch: Effect of Pressing Force

A subjective test was developed suitable for evaluating the effect of mobile communications devices on sentence intelligibility in background noise. Originally a total of 25 lists, each list including 16 sentences, were developed in British English and Finnish to serve as the test stimuli representative of adult language today. The sentences, produced by two male and two female speakers, were normalized for naturalness, length, and intelligibility in each language. The sentence sets were balanced with regard to the expected lexical and phonetic distributions in the given language. The sentence lists are intended for adaptive measurement of speech reception thresholds (SRTs) in noise. In the verification of the test stimuli, SRTs were measured for ten subjects in Finnish and nine subjects in English. Mean SRTs were −2.47 dB in Finnish and −1.12 dB in English, with standard deviations of 1.61 and 2.36 dB, respectively. The mean thresholds did not vary significantly between the lists or the talkers after two lists were removed from the Finnish set and one from the English set. Thus the numbers of lists were reduced from 25 to 23 and 24, respectively. The statistical power of the test increased when thresholds were averaged over several sentence lists. With three lists per condition, the test is able to detect a 1.5-dB difference in SRTs with the probability of about 90%.

/pdf/developing-a-speech-intelligibility-test-based-on-measuring-2solo7fjnh.pdf

Hanna Järveläinen

Papers

Audibility of the timbral effects of inharmonicity in stringed instrument tones

More About This Reverberation Science: Perceptually Good Late Reverberation

Reverberation Modeling Using Velvet Noise

Vibrotactile Sensitivity in Active Touch: Effect of Pressing Force

Developing a speech intelligibility test based on measuring speech reception thresholds in noise for English and Finnish.