2.2. Microphone Sensor Array system
A Microphone Sensor Array consists of multiple Microphones placed at different spatial positions and each of these microphones acts as an individual sensing unit. The output of a single Microphone based acoustic system is associated with different inefficiencies; the output degrading factors can be removed by using an array of microphone sensors.
Microphone Arrays have become largely more common in the various audio systems related to our real life, to acquire, noise filtering and enhancement of sound signals. The sound field visualization by a Microphone Array can be done in the following ways:
- Localization of sound sources
- Spatial and temporal analysis of sound propagation in closed spaces
- Acoustical Parameters evaluation for certain space
- Capturing of high fidelity sound through Array Signal Processing and successively noise reduction
- Acoustic Holography
- Beam-forming technique
2.3. Working principles of Microphone Array
A microphone array is used to filter audio signals by spatially sampling of their wave-fronts, in a space-time domain. Each Microphone provides one spatial sample of the input sound pressure variations as its output. The Microphone Sensor Array can be regarded as a single device that assembles the individual spatial samples from its elements, i.e. Microphones and transforming them into the desired result, i.e. Vector of Spatial Samples or Signal Vector. Further,
- Spatial Sample
The measurement of single Microphone at specific location
- Array Snapshot:
A single observation, i.e. Signal vector or set of Microphone measurements at given temporal instant is called Array Snapshot
Microphone array system samples signals both in the time-domain, i.e. snapshots and also in spatial -domain, i.e. sensor observation at specific location. The Array snapshots i.e. Vectors of Spatial Measurement can be subject to further processing by using a suitable filtering algorithm. This filtering may be expressed in terms of dependence on following factors
- Angle of Arrival
- Wave-number, i.e. spatial frequency of a wave. It is also called as propagation number and is defined as the number of wavelengths per unit distance, or in terms of wavelength
