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Membrane absorbers, which are commonly used types of resonance absorbers, convert sound energy into thermal energy by exploiting vibrations that occur on oscillating panels. Those types of absorbers are generally tuned to be efficient in a very narrow frequency range. However, if plates are used as the front panel, it is possible to broaden the effective absorbing frequency bandwidth by exciting multiple modes. This study is devoted to investigating the multimodal behaviour of plate absorbers with closed back volumes in low-frequency range. In the numerical part of the study, the box-shaped plate absorbers are modelled using a combined BEM/FEM approach. The results are validated with measurements conducted in an anechoic chamber. In addition, the sound absorption characteristics of the plate absorbers are obtained from an experimental study conducted in a reverberation chamber. The obtained results reveal that the plate absorbers can be effective in wider frequency ranges.

Flat panel loudspeakers are a promising alternative to conventional loudspeakers. In particular, quasi-omnidirectional radiation at higher frequencies is stressed as an advantage of these systems compared to conventional speaker systems. However, this advantage can also be considered a disadvantage. Compared to that from conventional speakers with a flat and smooth on-axis and off-axis response, this wide radiation from flat panel loudspeakers occurs with an inconstant directivity factor, which can cause coloration and unusual spatial artifacts. This paper investigated the root causes of inhomogeneous directivity by using numerical methods. Based on these analyses, specific prototypes with various damping layups were built to overcome this problem. The additional damping layer reduces the off-axis radiation without significantly reducing the pressure level in the listening window. This approach is simple, robust, inexpensive and effective for improving the directivity of flat panel loudspeakers.

This chapter addresses sensors and actuators for three main sensory modalities: hearing, vision, and touch. Technology in recent years was often focused on flat displays, e.g., or smartwatches. In contrast, the focus of this chapter is on wearable technologies of the post-smartphone area, allowing rich sensory input and output modalities. New approaches for tactile feedback include fiber-based sensors and actuators for e-textiles as well as complex 3D-fiber structures. Wearable sound sources and innovative sound-projection solutions using perceptual knowledge can replace complex distributed channel systems. One way to reduce latencies in vision are Organic Light-Emitting Diode (OLED) eyeables, that have the potential to significantly improving reaction time and power consumption. Combining the expertise of human perception and action with that on sensors and actuators contributes to augmented perception and interaction to exchange perceptual knowledge, which is needed for holistic sensor and actuator development. Moreover, sensors and actuators combined with tactile electronics in terms of flexible electronics and circuits for interfacing/processing explore new technologies for haptic and robotic systems.

The wood of the spruce tree (Picea spp.) has been valued for centuries as an ideal soundboard for stringed instruments due to its material acoustic properties. There is large variability in these properties between individual trees of the same species and even within an individual log. It stands to reason that this variability would produce audible differences in the sound quality of otherwise identical musical instruments. Furthermore, there may be a suite of physical characteristics of the soundboard that would result in optimal sound quality for a given design. Nine steel-string guitars of the same model were produced. The guitars varied only in two parameters: the density and Young's modulus of the soundboard and bracewood. This variability was representative of the range of wood currently produced by Pacific Rim Tonewoods. A short music sequence was used for a pairwise preference evaluation in a listening test. The results suggested that, for this particular model (the Taylor 814ce Grand Auditorium), the low density and Young's modulus of the soundboard and bracewood had a positive impact on the sound quality. More generally, these results underscore the importance of integrating a given design with the physical characteristics of the component wood.

The wood of the spruce tree (Picea spp.) has been valued for centuries as an ideal soundboard for stringed instruments, due to its material acoustic properties. There is large variability in these properties between individual trees of the same species, and even within an individual log. It stands to reason that this variability would produce audible differences in sound quality in otherwise identical musical instruments. Further, there may be a specific combination of material properties of the soundboard that would result in optimal sound quality for a given design, as measured by expert listeners. Nine steel string guitars of the same model were produced by the Taylor Guitar Company, with strict control of all production parameters. The guitars varied only in two parameters: the density and the Young's modulus of the soundboard and bracewood. A short music sequence was used for pairwise comparisons in a double-blind listening test. The results suggest that, for this particular model (the Taylor 814ce Grand Auditorium), low density and Young's modulus of the soundboard and bracewood have a positive impact on overall preference. More generally, these results underscore the importance of integrating a given design with the physical characteristics of the component wood.The wood of the spruce tree (Picea spp.) has been valued for centuries as an ideal soundboard for stringed instruments, due to its material acoustic properties. There is large variability in these properties between individual trees of the same species, and even within an individual log. It stands to reason that this variability would produce audible differences in sound quality in otherwise identical musical instruments. Further, there may be a specific combination of material properties of the soundboard that would result in optimal sound quality for a given design, as measured by expert listeners. Nine steel string guitars of the same model were produced by the Taylor Guitar Company, with strict control of all production parameters. The guitars varied only in two parameters: the density and the Young's modulus of the soundboard and bracewood. A short music sequence was used for pairwise comparisons in a double-blind listening test. The results suggest that, for this particular model (the Taylor 814ce G...

We listen to music not only with our ears. The whole body is present in a concert hall, during a rock event, or while enjoying music reproduction at home. This chapter discusses the influence of audio-induced vibrations at the skin on musical experience. To this end, sound and body vibrations were controlled separately in several psychophysical experiments. The multimodal perception of the resulting concert quality is evaluated, and the effect of frequency, intensity, and temporal variation of the vibration signal is discussed. It is shown that vibrations play a significant role in the perception of music. Amplifying certain vibrations in a concert venue or music reproduction system can improve the music experience. Knowledge about the psychophysical similarities and differences of the auditory and tactile modality help to develop perceptually optimized algorithms to generate music-related vibrations. These vibrations can be reproduced, e.g., using electrodynamic exciters mounted to the floor or seat. It is discussed that frequency shifting and intensity compression are important approaches for vibration generation.

This study presents a novel electrotactile display which can be integrated in current handheld devices with touch screens. Experiments were conducted to investigate the simulation of textures by using electrotactile display technique1.

In this study, experiments were conducted to determine if a person could distinguish percussive audio loops by their fingertips using audio-driven tactile feedback. The audio signal was adapted to generate a vibration signal (tactile feedback) taking into account the limited capabilities of the tactile modality. A systematic approach to find the different adaptation parameters is discussed. The vibrations were created by an electro-dynamic shaker mounted behind a touch-sensitive screen. Results indicate percussive loops are best distinguished if the source features (e.g., frequency spectrum) and sequence features (e.g., rhythm) are maintained. Also, the pragmatic and hedonic qualities of an interactive, multimodal system using audio-driven tactile feedback were evaluated using a semantic differential.

When playing a violin, the musician communicates with his instrument not only through his ears but also his fingers, chin, shoulder, and eyes. He uses different sensory inputs, which are provided by different sensory channels, such as auditory, tactile, kinesthetic, and visual, to play his musical instrument. The perceived vibrations are useful for the player to feel and to control the instrument. The interaction between sound and vibration plays also a role on the overall instrument perception. In this study, violin vibrations and their interaction with violin sounds were evaluated. Therefore, the vibration amplitudes of the neck and the violin sounds were recorded simultaneously during normal playing. The vibration recordings were analyzed, and then additional stimuli were generated by filtering or modifying frequency components. In the first experimental session, the vibration stimuli, which were presented to the subjects via a mini electrodynamic shaker, were evaluated. In the second experimental session, an investigation with multimodal (auditory-haptic) stimuli was conducted. The results show the importance of vibrations on the overall perception of the instrument and provide information on useful vibration features for the player-instrument interaction.

In this paper we introduce a methodology of semio‐acoustics to get information on how human listeners associate meaning to acoustic‐auditory events. We concentrate on identifying cues in the auditory stream listeners base the association of meaning on as well on modelling major characteristics of the reference system of meaning. The methodology we use is closely related to structuralism, an approach that has its origins in semiotics. In principle, structuralism differentiates between creating functions, carrying functions and changing functions of systems of meaning. We concentrate on carrying and changing functions here using the following procedure: a sign‐carrier (in our case an acoustic‐auditory event the association of meaning is based on) is decomposed into sub‐units. By a minimal pair analysis we investigate carrying and changing functions of acoustic‐auditory features with regard to the associated meaning. We will introduce the methodology used and discuss first results of a pilot study.