Detection of live speech

A system for detecting live speech, wherein the system is configured to perform a method comprising:

• receiving a signal containing speech;
• obtaining a first component of the received signal in a first frequency band, wherein the first frequency band includes audio frequencies;
• obtaining a second component of the received signal in a second frequency band higher than said first frequency band;
• detecting modulation of the first component of the received signal;
• detecting modulation of the second component of the received signal;
• comparing the modulation of the first component of the received signal and the modulation of the second component of the received signal;
• and
• determining whether the speech is live speech, depending on a result of comparing the modulation of the first component of the received signal and the modulation of the second component of the received signal;
• wherein determining whether the speech is live speech comprises:
• determining that the speech may have been replayed through a sound reproduction device if the modulation of the first component of the received signal differs from the modulation of the second component of the received signal.

A non-transitory computer readable storage medium having computer-executable instructions stored thereon that, when executed by processor circuitry, cause the processor circuitry to perform a method comprising:

• receiving a signal containing speech;
• obtaining a first component of the received signal in a first frequency band, wherein the first frequency band includes audio frequencies;
• obtaining a second component of the received signal in a second frequency band higher than said first frequency band;
• detecting modulation of the first component of the received signal;
• detecting modulation of the second component of the received signal;
• comparing the modulation of the first component of the received signal and the modulation of the second component of the received signal;
• and
• determining whether the speech is live speech, depending on a result of comparing the modulation of the first component of the received signal and the modulation of the second component of the received signal;
• wherein determining whether the speech is live speech comprises:
• determining that the speech may have been replayed through a sound reproduction device if the modulation of the first component of the received signal differs from the modulation of the second component of the received signal.