Audio signal storing apparatus having a function for converting speech speed

An audio signal storing apparatus having a function for converting speech speed, comprising:

• a microphone for converting an acoustic signal into an electric signal;
• a first analog amplifier for amplifying an output of said microphone;
• a first low-pass filter for removing high-frequency components from an output of said analog amplifier;
• an A/D converter for converting an output of said analog amplifier into a digital signal;
• a memory means for storing input speech data and data obtained as a result of signal processing;
• a digital signal processor for reading out data from said memory means and for carrying out digital signal processing to execute a speech speed changing process for the acoustic signal in accordance with an external speech speed conversion instruction;
• means for controlling said speech speed changing process executed by said digital signal processor;
• means for changing a parameter of said speech speed changing process;
• selecting means for receiving said speech speed conversion instruction and causing said digital signal processor to execute as said speech speed changing process one of the following processings:
• a first processing for storing input speech data into said memory means while the speech data are read out from said memory means, and for outputting the speech data read out from said memory means without changing the speech speed,
• a second processing for reading out the speech data stored in said memory means in the past and for outputting the past speech data read out from said memory means without changing the speech speed, and
• a third processing for executing said speech speed changing process for the speech data read out from said memory means;
• a D/A converter for converting digital speech data outputted from said digital signal processor into an analog speech signal;
• a second low-pass filter for removing high-frequency components from outputs of said D/A converter;
• a second analog amplifier for amplifying an output of said second low-pass filter;
• and
• a head-phone for converting an output of said second analog amplifier into an acoustic signal and for supplying the acoustic signal to ears of a user.

An audio signal storing apparatus having a function for converting speech speed, comprising:

• audio signal input means for taking in an audio signal;
• a ring buffer for storing said audio signal;
• an audio signal processing means for executing one of the following processing modes:
• a through mode for storing audio signal into said ring buffer while the audio signal is read out from said ring buffer and for outputting the audio signal read our from said ring buffer without changing the audio signal speed,
• a repeat mode for reading out the audio signal stored in said ring buffer in the past and for outputting the past audio signal read our from said ring buffer without changing the audio signal speed, and
• a speech speed changing mode for executing a speech speed changing process for the audio signal read out from said ring buffer;
• wherein, in said speech speed changing mode, average power of said audio signal is calculated in each input frame unit, said speech speed changing process being executed only in a case where said average power is higher than a predetermined threshold value, and the audio signal of frame unit being directly outputted in a case where said average power is lower than said predetermined threshold value,
• said speech speed changing mode being executed as a pipeline process by each frame unit with use of a plurality of input frame buffers in such a manner that for data of every frame a pitch extraction process is applied to a leading portion of the frame to detect a pitch of the leading portion, data of a length of one pitch thus detected is transferred to output buffers, data of a length of two pitches is multiplied by a window function which changes from 0 to 1 and by a window function which changes from 1 to 0, respective data obtained by the multiplications by the window functions are added together to thereby generate a reproduced wave pattern having a time length of two pitches, the reproduced wave pattern being inserted in the rear of the preliminary transferred data of the length of one pitch, a pitch detection process is again carried out while spearheaded by a position preliminary subjected to the pitch extraction process to thereby perform pitch detection at said position, and data of the length of n pitches (n is an integer) based on the pitch length obtained by the final pitch detection to the output buffers;
• a switch for causing said audio signal processing means to execute as said speech speed changing process one of said processing modes of the audio signal processing means;
• and
• output means for outputting an output of said audio signal processing means as an audio signal.

A speech speed conversion apparatus for receiving an input speech and for changing output time without changing a pitch of said input speech, comprising:

• a portable case having a speech input microphone disposed on a surface of the case, an output control switch, and a speech output terminal, said case being as small as a palm;
• said case includes:
• compressing means coupled to said input microphone for digitally compressing said input speech in each predetermined length, said compressing of the input speech being deleting of data bit, wherein a speech power is smaller than a first threshold value and the period is longer than a predetermined time length,
• a memory for storing the compressed speech data in an order of time series,
• decompressing means for reading out the compressed speech data of the predetermined length from said memory and for releasing said compressed speech data from the compression,
• speech speed converting means for outputting the decoded speech data in response to an instruction from said output control switch and for converting the speed of said speech data in such a manner that the decompressed speech data, in a period where the power of speech data is larger than a second threshold value, is maintained in constant pitch and the time axis is extended longer than the input time of said period;
• and
• output means for supplying an output from said speech speed converting means to said speech output terminal.

An audio signal storing apparatus having a function for converting speech speed, comprising:

• audio signal input means for taking in an audio signal;
• a memory for digitizing said audio signal and storing the digitized audio signal in accordance with a writing pointer;
• an audio signal processing means for executing one of the following processing modes for the audio signal read out from a reading pointer position of said memory:
• a through mode for outputting a read-out audio signal from said memory in such a manner that a reading pointer position is same as a writing pointer position,
• a repeat mode for outputting the audio signal read out from said memory by setting the reading pointer position which is returned back by a predetermined time from the writing pointer, and
• a speech speed changing mode for outputting the audio signal by executing a speech speed changing process for the audio signal read out from said memory in such a manner that the reading pointer position is gradually delayed from the writing pointer;
• switch for causing said audio signal processing means to execute as said speech speed changing process one of said three processing modes of said audio signal processing means;
• and
• output means for converting the output of said audio signal processing means to an analog signal and outputting said analog signal as an audio signal.