Speech coding by time-frequency interpolation (TFI) has recently been shown to offer high-quality coded speech at about 4 Kbps ,. This paper presents an improved TFI coder capable of delivering high-quality speech at 2.4 Kbps. The TFI method is briefly revisited and the structure of the coder is described. The performance of the 2.4 Kbps TFI coder is demonstrated by means of Mean Opinion Scores (MOS). It is shown that the coder performs almost the same as the full-rate standard coders GSM (13 Kbps)  and IS54 (8 Kbps).
Keywords: Speech Coding, Time-Frequency Interpolation, Vector Quantization.
Bibliographic reference. Shoham, Yair (1993): "High-quality speech coding at 2.4 kbps based on time-frequency interpolation", In EUROSPEECH'93, 741-744.