Patent ID: 8824698
Filing Date: 2014-09-02
Classification: H04R

Abstract:
1. An integrated circuit device having a circuit board, the circuit board comprising: a first vibrating membrane which forms a first microphone; a second vibrating membrane which forms a second microphone; and a differential signal generating circuit which receives a first voltage signal obtained in the first microphone and a second voltage signal obtained in the second microphone and generates a differential signal indicating a difference between the first and second voltage signals, wherein an inter-center distance between the first and second vibrating membranes is set to a distance in which a phase component of a voice intensity ratio which is a ratio of the intensity of a differential sound pressure of a voice entering the first and second vibrating membranes to the intensity of a sound pressure of a voice entering the first vibrating membrane, with respect to voice in a frequency band of 10 kHz or less, is equal to or smaller than zero decibels, wherein a value of Δr/λ is set so that a value of ρ(N) is zero or less in the following expression: where ρ(N) is a noise intensity ratio which is a ratio of the intensity of a noise component included in the differential signal to the intensity of a noise component included in the first or second voltage signal, Δr is an inter-center distance between the first and second vibrating membranes and λ is a wavelength of a noise.