Laura Laaksonen

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Quality and intelligibility of narrowband telephone speech can be improved by artificial bandwidth extension (ABE), which extends the speech bandwidth using only information available in the narrowband speech signal. This paper reports a three-language evaluation of an ABE method that has recently been launched in several of Nokia's mobile telephone models.(More)
The limited bandwidth of 0.3-3.4 kHz in current telephone systems reduces both the quality and the intelligibility of speech. Artificial bandwidth expansion is a method that expands the bandwidth of the narrowband speech signal in the receiving end of the transmission link by adding new frequency components to the higher frequencies, i.e., up to 8 kHz. In(More)
The limited audio bandwidth used in telephone systems degrades both the quality and the intelligibility of speech. This paper presents a new method for the bandwidth extension of telephone speech. Frequency components are added to the frequency band 4-8 kHz using only the information in the narrowband speech. First, a wideband excitation is generated by(More)
The quality of narrowband telephone speech can be improved by artificial bandwidth extension. So far, bandwidth extension methods have been evaluated with objective measures and subjective listening-only tests, whereas realistic conversational evaluations have been rare. This article presents a conversational evaluation of two bandwidth extension methods in(More)
Efficient teleconference system can be created by extending the speech bandwidth and using spatial audio. If wideband speech transmission was not supported as such, an alternative way to extend the bandwidth is by exploiting an artificial bandwidth extension (ABE) algorithm. In such methods the audio bandwidth is extended in the receiving end, without any(More)