In addition, the number of elements are doubled in this design. In the plot the patterns from 1, 2, and 4 kHz are essentially identical to each other, but the 3kHz pattern is still different. The 5 cm spacing in the array is approximately half wavelength at 4 kHz. Note that although the audio frequency band spans from 20 Hz to 20 kHz, the 1-4 kHz bands are particularly important for speech intelligibility. For illustration purpose, let us define a 2-element array with a 5 cm spacing and look at its pattern between 1-4 kHz. Several such beamforming algorithms are covered in the Acoustic Beamforming Using a Microphone Array example.Īlthough additive microphone arrays are very useful, they suffer from several limitations. For an additive microphone array, the goal is to coherently combine the signals from each channel so we can form a narrow beam towards the source and improve the signal to noise ratio. The additive microphone arrays are similar to the arrays used in other applications, like wireless communications. Depending on the layout, microphone arrays can be divided into two main categories: additive microphone arrays and differential microphone arrays. Microphone arrays have been deployed in many audio applications.

Additive sequence of an array