This paper studies the problem of optimally recovering the input signals to a linear time-invariant system when both input and measurement noises are present. We focus on batch-form solutions which are suitable for applications that deal with short-duration events. The system, the input and measurement noise covariances, the noise-corrupted output signals are assumed known, and we seek to recov...

A 1 μm diameter platinum wire resistance thermometer has been used to measure temperature fluctuations generated during a static GEM-60 rocket motor test. Exact and small-signal relationships between acoustic pressure and acoustic temperature are derived in order to compare the temperature probe output with that of a 3.18 mm diameter condenser microphone. After preliminary plane wave tests yiel...

Scope Sufficient acoustic quality of speech communication is very important in many different situations and places; classrooms in schools, auditoria, PA systems in public buildings, alert and warning systems in noisy environments etc. Speech transmission index (STI) is an objective method for prediction and measurement of speech intelligibility. This is a guide how to use ODEON for calculating...

In recent years, environmental noise has become a major concern in large urban areas, significantly reducing the quality of life and health. The measurement, localization and monitoring of various environmental noise sources are the key elements of success in tackling the urban noise problem. However, the deployment of fixed microphones at a dense grid of locations becomes prohibitively expensi...

Time-delay estimation technique is a key to acoustic temperature field measurement. In order to acquire a stable acoustic time-of-flight in low SNR, a time-delay estimation method combined multilayer cross-correlation and multilayer auto-correlation (MC method for short) is proposed. Crosscorrelation method and second correlation method are described briefly for comparison. Theory analysis and ...

The role and application of the concepts of soundscape planning, vis-à-vis those of environmental noise management, need elaboration. In noise control, sound is a waste product managed to reduce the immision of sounds that cause human discomfort. The soundscape approach, by contrast, considers the acoustic environment as a resource, focussing on sounds people want, or prefer. Quiet is not a cor...

Flow disturbances are generated inside a duct via pulsed injection of helium into a flow of air. This leads to the generation of an acoustic pulse (direct noise), as well as the production of entropic and compositional inhomogeneities which are convected with the mean flow. As these inhomogeneities are convected through a choked nozzle, they generate indirect noise. The resulting acoustic press...

Active noise control (ANC) is an effective technique used to reduce noise levels at the controlled points by introducing a cancellation sound wave into the primary acoustic field. To achieve better sound design and noise attenuation, it is critical to have good knowledge of the characteristics of the primary noise source, which is also necessary for condition monitoring (CM). This paper investi...