VOICE INPUT DEVICE AND DISPLAY DEVICE
An voice input device includes a wave guide unit for guiding an incident sound wave, a microphone unit for converting a sound wave guided through the wave guide unit to an electrical sound signal, and a signal processing unit for processing the sound signal obtained by the microphone unit, using an acoustic characteristic given by the wave guide unit to the sound wave, in which, the wave guide unit has a structure which gives the acoustic characteristic that is different between direct sound, which is sound that reaches the microphone unit without reflecting off an internal surface of the wave guide unit, and indirect sound, which is sound that is reflected off the internal surface before reaching the microphone unit, and the signal processing unit determines whether or not the direct sound is input based on a difference in the acoustic characteristic between the direct sound and the indirect sound.
1 . A voice input device comprising:
a wave guide unit configured to guide an incident sound wave;
a microphone unit configured to convert a sound wave that has passed through the wave guide unit to an electrical sound signal; and
a signal processing unit configured to perform signal processing on the sound signal obtained in the conversion by the microphone unit, using an acoustic characteristic that is given by the wave guide unit to the sound wave,
wherein the wave guide unit has a structure which gives the acoustic characteristic that is different between direct sound and indirect sound of the sound wave that has passed through the wave guide unit and entered the microphone unit, the direct sound being sound that reaches the microphone unit without reflecting off an internal surface of the wave guide unit, the indirect sound being sound that is reflected off the internal surface before reaching the microphone unit, and
the signal processing unit is configured to perform a direct-sound detection process which determines whether or not the direct sound is input, using a difference in the acoustic characteristic between the direct sound and the indirect sound.
2 . The voice input device according to claim 1 ,
wherein in the direct-sound detection process, the signal processing unit is configured to (i) determine whether or not a sound pressure level of the electrical sound signal is greater than or equal to a threshold in a determination frequency range which is provided in a range above a resonance frequency between the direct sound and the indirect sound, and (ii) detect an input of the direct sound when the sound pressure level of the electrical sound signal is determined to be greater than or equal to the threshold.
3 . The voice input device according to claim 1 ,
wherein the signal processing unit includes:
a low-cut filter which removes or reduces a signal in a frequency range below a determination frequency that is provided in a range above a resonance frequency between the direct sound and the indirect sound; and
a comparator which compares a predetermined threshold to a level of an output signal from the low-cut filter, and provides a control signal indicating detection of the direct sound when the level of the output signal from the low-cut filter is greater than the predetermined threshold.
4 . The voice input device according to claim 1 ,
wherein the wave guide unit has an upper wave guide unit which the sound wave enters and a lower wave guide unit to which the microphone unit is provided, and
a cross-sectional area of the upper wave guide unit is smaller than a cross-sectional area of the lower wave guide unit.
5 . A display device comprising:
the voice input device according to claim 1 ;
a display panel which displays display data per unit of display;
a storing unit configured to store the display data; and
a display control unit configured to switch a display on the display panel from a current unit of display to a next unit of display when the input of the direct sound is detected by the signal processing unit in the voice input device.
6 . The display device according to claim 5 ,
wherein the storing unit is configured to store, as the display data, score data for displaying a musical score,
the display panel displays the score data per unit of display, the unit of display including one or more pages of the musical score, and
the display control unit is configured to switch the display on the display panel so as to include a page following a last page of currently displayed one or more pages of the musical score when the input of the direct sound is detected.