Abstract: A method and apparatus to detect voice activity by using a zero-crossing rate includes removing noise included in an audio signal, adding a random signal having energy of a predetermined size to the audio signal from which noise is removed, extracting predetermined voice detection parameters from the audio signal to which the random signal is added, and comparing the extracted predetermined voice detection parameters with a threshold value and determining voice and non-voice activities.

Abstract: Provided are a method and apparatus for detecting a pitch period of an input signal, the method including: generating division frames by dividing the input signal by a unit of a first predetermined number of samples at a time domain; detecting a reference sample which has a peak value in each division frame; generating extraction frames by extracting a second predetermined number of samples on the basis of the reference sample of each division frame; and detecting the pitch period of the input signal based on a similarity among the extraction frames.

Abstract: A robust method and apparatus to detect voice activity based on the power level of an audio frame. The method may include performing primary active/non-active voice period determination of an input audio frame according to a power level of the audio frame, extracting a noise power prediction value and a signal power prediction value by referring to power levels of current and previous audio frames according to a primary active/non-active voice period determination value, and performing secondary active/non-active voice period determination for the input audio frame by comparing the extracted signal power prediction value with the extracted noise power prediction value.

Abstract: A method and apparatus to detect voice activity by using a zero-crossing rate includes removing noise included in an audio signal, adding a random signal having energy of a predetermined size to the audio signal from which noise is removed, extracting predetermined voice detection parameters from the audio signal to which the random signal is added, and comparing the extracted predetermined voice detection parameters with a threshold value and determining voice and non-voice activities.

Abstract: An audio playback speed control method and apparatus to control an audio playback speed using an optimal frame length with a small amount of calculation. The audio playback method includes extracting an audio sampling frequency and audio playback speed information from an audio signal which is reproduced, determining a length of an input frame, a length of an output frame, and a length of an overlapping region between frames, on a basis of the audio sampling frequency and the audio playback speed information and performing different overlapping and adding methods, according to the audio playback speeds, on a basis of the length of the input frame, the length of the output frame, and the length of the overlapping region between the frames.