Setting the tone: Considerations for educating the next generation of sound reproduction professionals

Despite the increase in prevalence of music technology and related programs industry bodies such as creative and cultural skills council, have continued to highlight the requirement for technically competent graduates to meet the growing demand from the wider audio and creative industries. Drawing upon academic literature, government and educational publications and empirical data gathered during student feedback and focus groups this paper explores the authors’ experiences of developing the curriculum in the sound reproduction subject area on an undergraduate Music Technology BSc (Hons) course. Commencing with an overview of the areas of the sound reproduction curriculum, the paper turns to some of the challenges faced by the authors in delivering this subject area in a formal educational setting. The paper then concludes by summarising some useful pedagogical approaches to deliver sound reproduction themes and points towards further ways in which the required skills and knowledge for industry could be addressed

Bit-rate saving in multichannel sound:using a band-limited channel to transmit the center signal

A method is proposed to achieve full-frequency-range three-channel (left, right, and center) sound reproduction in systems that have only two full-range sound channels and some band-limited commentary channels. The low-frequency part of the center signal, which matches the bandwidth of the commentary channels, is added to the (multilingual) speech signals in each of the commentary channels. The remaining high-frequency part is added in the left and right channels as in conventional mixdowns. Sound reproduction of this signal by a conventional two-channel receiver remains unaltered. The low-frequency part of the center signal is mixed to the left and right signals together with the speech once the user has selected a commentary channel. Three-channel reproduction is obtained by routing the selected commentary channel to a central loudspeaker. Listening tests revealed that sound reproduction according to the proposed scheme could not be distinguished from original three-channel reproduction. This scheme can be applied to proposed standards such as D2MAC and MPEG2.</p

A Sub-band Filter Design Approach for Sound Field Reproduction

The purpose of sound field reproduction is to use loudspeakers to produce desired sound at particular locations in a given environment, which has a wide range of applications such as virtual reality, etc. The computational load required to design and implement filters involved in sound reproduction systems can be significant, especially when the desired sound has rich information over a wide frequency band. To reduce the computational load, sub-band filtering approaches are usually used in sound reproduction systems. In the present work, an approach is proposed to design the sub-band filters used in sound reproduction systems in a more convenient way, where the filter design problem is formulated into a convex optimization problem. Detailed analysis has been conducted on how to specify the response characteristics of each sub-band and how different sub-band filters can be combined into one full band filter in the design and implementation of the system. Results also show that even if the sub-band filter structure is not necessary, this approach can also be applied to reduce the computational load in designing inverse filters when the plant responses involve relatively large differences in delay time among different frequency bands

Adaptive noise reduction circuit for a sound reproduction system

A noise reduction circuit for a hearing aid having an adaptive filter for producing a signal which estimates the noise components present in an input signal. The circuit includes a second filter for receiving the noise-estimating signal and modifying it as a function of a user's preference or as a function of an expected noise environment. The circuit also includes a gain control for adjusting the magnitude of the modified noise-estimating signal, thereby allowing for the adjustment of the magnitude of the circuit response. The circuit also includes a signal combiner for combining the input signal with the adjusted noise-estimating signal to produce a noise reduced output signal

Between Air and Electricity

After the sound reproduction industry had claimed “perfect high fidelity” for sound recordings already at the beginning of the twentieth century, composers and sound artists challenged this perfection by tweaking microphones and loudspeakers to make them act as a musical instrument instead of a mere sound reproduction device. This book explores the instrumental use of microphones and loudspeakers in music beginning in the 1950s. The popular noise musician Merzbow, over-minimalist classic Alvin Lucier, cult instrument inventor Hugh Davies, and contemporary visual artist Lynn Pook made audible what was supposed to remain silent

Adaptive gain and filtering circuit for a sound reproduction system

Adaptive compressive gain and level dependent spectral shaping circuitry for a hearing aid include a microphone to produce an input signal and a plurality of channels connected to a common circuit output. Each channel has a preset frequency response. Each channel includes a filter with a preset frequency response to receive the input signal and to produce a filtered signal, a channel amplifier to amplify the filtered signal to produce a channel output signal, a threshold register to establish a channel threshold level, and a gain circuit. The gain circuit increases the gain of the channel amplifier when the channel output signal falls below the channel threshold level and decreases the gain of the channel amplifier when the channel output signal rises above the channel threshold level. A transducer produces sound in response to the signal passed by the common circuit output