Telecommunication terminal able to modify the voice transmitted during a telephone call
A telecommunication terminal receives an analog speech signal from a user of the terminal and converts the analog speech signal into a digital signal. A vocoder applies source coding to the speech signal and extracts reconstruction parameters from the speech signal. The reconstruction parameters are modified so that the transmitted voice associated with the signal is modified.
1. A telecommunication terminal comprising:
a receiver configured to receive an analog speech signal representing speech of a user of the terminal;
an analog to digital converter configured to convert the analog speech signal into a digital signal;
a coding and extracting unit configured to extract a plurality of reconstruction parameters from the digital signal, the reconstruction parameters including log area ratio coefficients, a fundamental frequency and a pulse excitation signal;
an interface configured to receive an instruction to modify at least one of the reconstruction parameters and, responsive to receiving the instruction, to control a source coder and modifying unit to modify at least one of the reconstruction parameters by a particular amount; and
a transmitter configured to transmit the digital signal including the modified reconstruction parameters external to the telecommunication terminal so that a voice associated with the transmitted digital signal has at least one characteristic different from the speech represented by the analog speech signal.
2. The terminal of claim 1 , wherein the source coder and modifying unit is further configured to perform regular pulse excited long term prediction (RPE-LTP) coding on the speech signal.
3. The terminal of claim 1 , wherein the fundamental frequency has an initial associated pitch and the source coder and modifying unit is configured to modify the initial associated pitch so that the transmitted digital signal has a modified associated pitch which is different from the initial associated pitch of the speech represented by the analog speech signal.
4. The terminal of claim 3 , wherein the initial associated pitch is modified to have a value of approximately 120 Hz.
5. The terminal of claim 3 wherein the initial associated pitch is modified to have a value of approximately 210 Hz.
6. The terminal of claim 3 , wherein the source coder and modifying unit is further configured to modify a gain of the speech signal.
7. The terminal of claim 6 , wherein the source coder and modifying unit is further configured to increase the initial associated pitch and to reduce the gain.
8. The terminal of claim 1 , wherein the source coder and modifying unit is configured to modify the reconstruction parameters according to a musical score.
9. The terminal of claim 8 , wherein the musical score is in a music format selected from the group consisting of a MIDI format, an SMAF format, a polyphonic EMR R5 format, and an IrDA iMelody format from Infrared Mobile Communications (IrMC).
10. The terminal of claim 1 , wherein the instruction that the interface is configured to receive indicates a type of modification that is to be made to the speech signal.
11. The terminal of claim 1 , wherein the instruction that the interface is configured to receive indicates which reconstruction parameters are to be modified and the particular amount by which each indicated reconstruction parameter is to be modified.